Completely cover the opening be securely fastened be labelled as a covering for an opening be made from material that can support any load that may be encountered on the worksite. Always use another means of fall protection when installing, removing or working near an unprotected opening.

What is the best barrier should be used for an opening in a floor?

Openings in slabs and shafts are sometimes changed and must be secured against falls during the construction process. Floor openings should be considered as an open slab edge and be secured with collective fall protection. For this you can use an attachment such as Socket base or Vertical bracket, and Post 1,3 m and Barriers.

What is the proper protection to use for a hole in the floor?

Preventing Falls Through Holes It has to be a terrible feeling. One moment your feet are on what seems to be a solid surface, the next moment they’re in mid-air as you begin a fall to a level far below. Openings in floors and roofs are often part of the work environment during construction, renovation and demolition.

What are two requirements for protection around floor openings?

Every stairway or ladderway floor opening should be guarded by a standard railing and toeboards. The railing and toeboards should be provided on all exposed sides except for the entrance to the opening.

What is fall protection around floor openings?

All About Floor Holes: OSHA’s Fall Protection Standards Floor holes are frequently present on construction sites. They can be found inside of buildings, on rooftops or roadways, and throughout outdoor jobsites. A floor hole presents trip or fall hazards to workers and can lead to serious injuries or fatalities. OSHA considers FALLS a serious hazard that are the cause for most of the fatalities in the construction industry. Floor holes must never be ignored! Always look for areas that may have floor holes and be aware of situations where holes may not be adequately marked, covered, barricaded, or guarded. Walking/working surfaces can be horizontal or vertical and may include floors, roofs, ramps, bridges, concrete reinforcing steel or any surface on which an employee walks or works to perform their job duties. OSHA categorizes floor holes into two main types:

1. Holes more than 6 feet deep that a person can fall into that require protection by fall arrest systems, guardrails or covers.
2. Holes less than 6 feet deep (no minimum depth specified) that require employees to be protected from tripping or stepping into the holes by placing covers over them.

Examples of floor holes include:

• Missing Floor Boards
• Sunken Gravel or Dirt
• Fully Enclosed Ladder
• Roof and Floor Drains
• Chipped or Broken Concrete
• Precast Concrete Openings
• Elevator Shafts
• Drilled Pier Holes
• Manholes
• Skylights

When a hole is not in use, always ensure it is protected by a cover or a guardrail system that is added along all unprotected sides of the hole. Floor holes or openings must be protected to prevent workers from tripping and/or falling into them. OSHA Standard 1926.501(b)(4)(ii) Each employee on a walking/working surface shall be protected from tripping in or stepping into or through holes by covers.

• The floor hole cover should be strong and durable enough to withstand at least twice the weight of employees, equipment and materials that may be imposed on the cover at anytime.
• If protective covers are not installed or available for floor holes noticed on the job site, immediately notify appropriate personnel to address the hazard.
• Skylights must have fall arrest systems, guardrails or covers to prevent falls to lower levels.
• Do not work near skylights unless adequate fall protection is in place.

OSHA Standard 1926.501(b)(4)(iii) Each employee on a walking/working surface shall be protected from objects falling through holes (including skylights) by covers. Open floor holes, including skylights, or floor holes with inadequate protection, may create a struck-by hazard to another person who may be walking or working below the floor hole. Floor hole covers should be installed or secured in a way to prevent accidental displacement by the wind, equipment or other employees. OSHA Standard 1926.502(i)(1) Covers located in roadways and vehicular aisles shall be capable of supporting, without failure, at least twice the maximum axle load of the largest vehicle expected to cross over the cover.

1. Never use paper, cardboard, a tarp, or other soft material to cover a floor hole.
2. Guard all new floor holes immediately.
3. Always use a personal fall arrest system (PFAS) when it is required to work near or over any uncovered opening more than 6-feet above a lower level.

Weeklysafety.com is giving away 10 free safety topics, no credit card required! Take advantage and grab your free set of safety meeting topics today by clicking the button below. A membership to Weeklysafety.com comes at a very low price that never goes up no matter how many employees you have and no matter how many awesome safety topics you use.

What material is best for air barrier?

The edges are a major challenge – The trick is in assembling these materials into a continuous seal at the boundary of the conditioned space. The key word is “continuous.” The most difficult spots to seal are not in the field but at the edges of the field, and the transitions from one material to another.

For example, plywood and rigid-foam insulation make good air barriers, but only when the seams between sheets have been sealed with a high-quality flashing tape. One of the earliest approaches to air-sealing—a technique called the Airtight Drywall Approach —relies principally on sheets of gypsum drywall for the air barrier.

Taping the seams creates a good air-seal in the field. Yet this system also relies on sealing the edges with beads of caulk at the top and bottom plates and around door and window openings. Penetrations through this barrier at electric boxes and recessed fixtures also must be sealed with caulk or special gaskets.

• Similarly, potential gaps between the bottom plate and the subfloor should be sealed with caulk or with a gasket.
• In other words, when two dissimilar materials meet, the potential for a leak is higher.
• One material that is rarely used these days as an air barrier is polyethylene sheeting, the stuff that once was routinely promoted as a vapor barrier.

One reason is that it’s difficult to seal polyethylene at penetrations, between sheets, and around electric boxes. Hidden problem areas also include utility chases, fireplace surrounds, recessed light fixtures, holes for plumbing under tubs and behind showers, and scuttles for attic access.

What is the OSHA floor opening?

Floor hole: an opening measuring less than 12 inches but more than 1 inch in its least dimension, in any floor, platform, pavement, or yard, through which materials but not persons may fall; such as a belt hole, pipe opening or slot opening.

What is the difference between a floor hole and a floor opening?

Key Terms: Floor Hole: opening less than 12 inches but more than 1 inch. Floor Opening: an opening greater than 12 inches where a person may fall.

What are the 3 requirements for a hole cover?

➢ Covers for holes in floors and working surfaces must meet the following requirements: ➢ Capable of supporting at least twice the maximum load expected to cross over the cover. ➢ Shall be secured when installed to prevent displacement. ➢ Shall be marked with word ‘HOLE’ or ‘COVER’.

What are the OSHA standards for floor holes?

November 17, 2004 Mr. Joe Mocka Roughneck Concrete Drilling & Sawing Co.8400 Lehigh Avenue Morton Grove, IL 60053-2617 Re: 29 CFR 1926.501(b)(4); 1926.502(i); CPL 02-00-124; Duty of a subcontractor to cover floor holes in a Multi-Employer worksite. Dear Mr.

Mocka: This is in response to your letter submitted on April 12, 2004, to the Occupational Safety and Health Administration (OSHA). We apologize for the delay in responding. We have paraphrased your question as follows: Question (1): Scenario: A subcontractor (“sub”) enters into a contract to drills holes in a floor.

During the contract discussions, the sub offers to include the cost of pre-fabricated, adjustable hole covers in the contract. The general contractor (“GC”) declines, stating that the GC will cover the holes itself. In this scenario, is the sub permitted to rely on the GC to cover the holes? If the GC failed to cover a hole, would the sub be subject to an OSHA citation? Answer Section 29 CFR 1926.501(b)(4) states: Holes.

(i) Each employee on walking/working surfaces shall be protected from falling through holes (including skylights) more than 6 feet (1.8 m) above lower levels, by personal fall arrest systems, covers, or guardrail systems erected around such holes. (ii) Each employee on a walking/working surface shall be protected from tripping in or stepping into or through holes (including skylights) by covers.

(iii) Each employee on a walking/working surface shall be protected from objects falling through holes (including skylights) by covers. These requirements must be met at the work site described in your scenario. Under OSHA’s Multi-Employer Citation Policy, CPL 02-00-124, responsibility for covering the holes depends on what role each employer is serving at the work site.

An employer has OSHA obligations under the policy if it serves in one or more of the following roles: creating, exposing, correcting, or controlling employer.1 Note, however, that matters involving contract law, such as who must bear the cost of the covers, for example, are beyond the purview of this office.

The responsibilities of the various employers on this work site in fulfilling OSHA requirements are discussed below. The multi-employer policy provides guidance to employers on how citations are to be issued for violations on work sites where more than one employer is citable for the same hazard.

1. Pursuant to the policy’s two-step analysis, employers must: (1) determine whether they have any responsibility for compliance with OSHA standards on the work site and, if so, (2) what steps must be taken to meet those requirements.
2. See CPL 02-00-124 sections (X)(A)(1)-(2).
3. The subcontractor as an exposing employer The sub is an “exposing employer,” since its own employees are exposed to the hazard posed by the holes.

The sub must take reasonable steps within its ability to ensure that its employees are protected. If the GC has stated that it will cover the holes, the sub must check to make sure that the GC follows through promptly and adequately so that the sub’s employees will be protected from the hazard.

• If, for example, the GC fails to promptly and adequately take steps to cover the holes, the sub retains the responsibility under §1926.501 to implement measures within its ability to protect its employees.
• Issues regarding which party must bear the cost of the protective measures in that instance are contractual, rather than OSHA issues.

The subcontractor as a creating employer The employer that creates a hazard is considered a “creating employer” and has an obligation to meet OSHA requirements to protect the employees of other employers. However, in your scenario, the sub offers to cover the holes, but the GC specifically excludes the covering of the holes from the sub’s contract.

In such circumstances the sub would be considered to have met its creating employer obligations (with respect to having drilled the holes in the first place) by offering to cover the holes. At that point, the GC will have assumed the responsibility of correcting the hazard. (See discussion of The GC as a correcting employer below.) This raises the question of what happens if the GC does not cover the holes in a timely manner, the sub covers the holes itself with its own covers (thereby ensuring its exposing employer responsibilities have been met) and, at the completion of the sub’s work, the sub removes its covers.

Although the removal of the covers would create a new hazard, in this case the sub would be considered to have met its OSHA obligations as a creating employer regarding that hazard once it gives adequate notice to the GC of its intention to remove them.2 The GC as a correcting employer In your scenario the GC specifically takes on the responsibility of covering the holes drilled by the sub.

• The GC thus becomes a “correcting employer” and must immediately cover the holes, as required under §1926.502(i), to fulfill its OSHA obligations and protect all employees on the worksite from the hazard.
• Question (2): Does the “Hole in One Cover” manufactured by Paragon Products meet the criteria requirements for covers for holes in floors? Answer: OSHA is generally precluded from approving or endorsing specific products.

The variable working conditions at job sites and possible alteration or misapplication of an otherwise safe piece of equipment could easily create a hazardous condition beyond the control of the equipment manufacturer. However, where appropriate, OSHA tries to give employers some guidance to help them assess whether products are appropriate to use in light of OSHA requirements.

• Strength requirement Floor hole covers must meet the applicable parts of §1926.502(i).
• Section 1926.502(i)(2) states: overs shall be capable of supporting without failure, at least twice the weight of employees, equipment, and materials that may be imposed on the cover at any one time.
• The engineering report provided with your letter states that the test unit used in that report has a failure pressure of 1,300 pounds when the cover is mounted over a 12-inch cylindrical opening and a failure pressure of 2,900 pounds when mounted over a 6-inch cylindrical opening.3 If the cover were to be used over a 12-inch cylindrical opening, the total weight that would potentially be imposed on the cover must be 650 pounds or less to fall within this requirement.

If the cover were used over a 6-inch cylindrical opening, the total weight must be 1,450 pounds or less. Given these results, it seems likely that the cover would fulfill the strength requirements in §1926.502(i)(2) in most situations. Securing requirement Section 1926.502(i)(3) states that: All covers shall be secured when installed so as to prevent accidental displacement by the wind, equipment, or employees.

The installation instructions for the “Hole in One” cover provided with your letter show that the cover has adjustable securing wedges that must be adjusted to fit the hole. So long as the adjustments are completed as specified in the manufacturer’s instructions, the cover is likely to fulfill the requirement in §1926.502(i)(3).

Marking requirement Section 1926.502(i)(4) states that: All covers shall be color-coded or they shall be marked with the word “HOLE” or “COVER” to provide warning of the hazard. The Features page for the “Hole in One” cover provided with your letter shows that these covers are a “safety orange color for easy recognition.” Because orange is a color typically used by the construction industry to signal a potential hazard, the cover color meets the color-coding requirement in §1926.502(i)(4).

If you need any additional information, please contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, Office of Construction Standards and Guidance, fax # 202-693-1689. You can also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, D.C.20210, although there will be a delay in our receiving correspondence by mail.

Sincerely, Russell B. Swanson, Director Directorate of Construction 1 Definitions of each role are provided in the policy. 2 This assumes that the sub is unaware of any lack of intention by the GC to cover the holes. 3 Please note the engineering report page sent does not specify whether the cover tested is the same model as that described in the letter.

Which fall protection control is the best?

Hierarchy of Fall Protection – The American National Standards Institute (ANSI)/American Society of Safety Engineers (ASSP) Z359, Fall Protection Code, has identified a hierarchy of fall protection controls, from most effective to least effective. The hierarchy includes:

• Elimination, Removing the need to work at an elevated height above the working surface, such as using an extension pole to replace light bulbs. Most effective control.
• Passive fall protection, Using physical barriers such as guardrails to prevent a fall.
• Fall restraint systems, Using positioning and fall restraint systems that restrict movement to prevent a fall.
• Fall arrest systems Use of full-body harness systems or safety nets, that work together to break a fall.
• Administrative controls, The use of policies, procedures, practices, training, and warnings to restrict worker actions and increase awareness of fall hazards. Least effective control.

In general, it is better to use fall prevention systems, such as guardrails, than fall protection systems, such as safety nets/fall arrest devices. That’s because prevention systems prevent falls from occurring in the first place. Watch these videos for more information on fall protection: 1.

What are the 3 types of fall protection?

Generally, fall protection can be provided through the use of guardrail systems, safety net systems, or personal fall arrest systems.

What are 3 fall protection rules?

What can be done to reduce falls? – Employers must set up the work place to prevent employees from falling off of overhead platforms, elevated work stations or into holes in the floor and walls. OSHA requires that fall protection be provided at elevations of four feet in general industry workplaces, five feet in shipyards, six feet in the construction industry and eight feet in longshoring operations.

Guard every floor hole into which a worker can accidentally walk (using a railing and toe-board or a floor hole cover). Provide a guard rail and toe-board around every elevated open sided platform, floor or runway. Regardless of height, if a worker can fall into or onto dangerous machines or equipment (such as a vat of acid or a conveyor belt) employers must provide guardrails and toe-boards to prevent workers from falling and getting injured. Other means of fall protection that may be required on certain jobs include safety harness and line, safety nets, stair railings and hand rails.

OSHA requires employers to:

Provide working conditions that are free of known dangers. Keep floors in work areas in a clean and, so far as possible, a dry condition. Select and provide required personal protective equipment at no cost to workers. Train workers about job hazards in a language that they can understand.

Do you guard every open sided floor or platform?

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only. September 18, 1979 Mr. John F. Perry Springer & Perry Attorneys At Law Suite 2300 301 Fifth Avenue Building Pittsburgh, Pennsylvania 15222 Dear Mr.

Perry: This is in response to your recent inquiry requesting clarification of OSHA’s position in the application of 29 CFR 1926.500(d)(1).29 CFR 1926.500(d)(1) requires every opensided floor or platform 6 feet or more above the adjacent floor or ground level to be guarded by a standard railing or the equivalent on all open sides, except where there is an entrance to a ramp, stairway, or fixed ladder.

In work situations where a standard railing is not practical, safety belts and lanyards attached to a structural member or static line meeting the requirements of 29 CFR 1926.104 may be used to prevent employees from walking off the edge of opensided floors or platforms.

1. Safety nets also may be used to protect employees erecting and installing Flexicore concrete slabs when the use of safety belts is impractical.
2. The roofing industry contends that they have a unique problem with flat roofs because the hot roofing material makes the use of a safety belt and lanyard impractical and the installation of flashing at the edge of the roof prevents the use of a standard railing and net.

We are now developing specific standards for the protection of the roofer. Although Patterson Construction Company periodically works on floors which are the top of a building in its unfinished state, such a floor is not a roof if it will subsequently be covered by another level.

• Such a floor is not subject to the same conditions that limit the use of guardrails and safety belts on flat roofs.
• Therefore, the Patterson Company is required to comply with 1926.500(d)(1) when working on these floors.
• We hope this information will be helpful to you.
• If we may be of any further assistance, please feel free to call or write.

Sincerely, Grover C. Wrenn Director, Federal Compliance and State Programs

Does concrete act as an air barrier?

While batt insulation (permeable: 20 perms) has practically no vapor resistance, 8′ of concrete is a pretty good barrier (impermeable: 0.5 perms) and latex paint on gypsum board is semi- permeable (about 3 perms).

Is concrete a good air barrier?

Q. What materials make good air barriers? – A. A wide variety of materials make good air barriers, including poured concrete, glass, drywall, rigid foam insulation, plywood, and peel-and-stick rubber membrane. (Note that evidence is increasing that OSB is not an air barrier; for more information on this issue, see Is OSB Airtight? ) Although air can’t leak through these materials, it can definitely leak at the edges or seams of these materials.

• When these materials are used to form an air barrier for your home, additional materials such as tape, gaskets, or caulk may be required to be sure seams and edges don’t leak.
• To make a good air barrier, a material not only needs to stop air flow; it also needs to be relatively rigid and durable.
• If you want to determine whether a material is an air barrier, hold a piece of the material up to your mouth and blow.

If you can blow air through it, it’s not an air barrier. Engineers distinguish between air barrier materials (drywall, for example), air barrier assemblies (for example, plywood with taped seams attached to wall framing), and air barrier systems (all of the materials and assemblies that make up a building’s air barrier).

Can concrete be an air barrier?

Precast Concrete for High Performance Building Envelopes October 2013 Sponsored by Precast/Prestressed Concrete Institute

• Continuing Education
• Use the following learning objectives to focus your study while reading this month’s Continuing Education article.
• Learning Objectives – After reading this article, you will be able to:

1. Explain how sustainability is one of a number of components that comprise high performance design
2. Discuss the attributes of precast concrete that contribute to a high performance building
3. Define the high performance building envelope strategies that utilize precast concrete
4. Describe the aesthetic options available with precast concrete envelope systems.

Sustainable. Energy efficient. Durable. For decades, these have been worthy goals for construction materials and systems. Yet as the environmental movement has evolved, these goals become ever more ambitious. Today these attributes—and others—are subsumed in a more all-encompassing term: high performance.

• The goal of high performance is to design and build structures that optimize all relevant high-performance attributes on a life-cycle basis rather than a solely first-cost basis.
• Essential in meeting project goals from environmental to aesthetic to economic, high-performance buildings are being increasingly required by owners and by legislation.

Critical to a high-performance building is a high-performance building envelope, that is, an envelope that provides versatility, efficiency, and resiliency. Precast concrete envelope systems inherently offer these attributes, and can be designed to provide many others.

At the heart of this definition is a fundamental shift in perspective from sustainable design and construction to sustainability and performance on a life-cycle basis. The concept of high-performance encompasses the concepts and practices of sustainability.

1. However, it goes beyond a piecemeal approach by requiring optimization of all relevant attributes for a project.
2. Characteristics such as energy and water conservation, safety, security, and durability are no longer just options, but requirements that must be integrated into a structure’s overall design, construction, and performance.

High-performance structures are essential to meeting a variety of demands, and accordingly, green codes and standards, funding entities, and owners are requiring them. Examples include the new International Green Construction Code, LEED (v.4), ASHRAE 189.1, and the mandate by the U.S.

• Federal Government Executive Order 13514 which requires government buildings to achieve net zero by 2030.
• Integral to high-performance structures are high-performance materials and systems—integrated systems that allow for design versatility and are efficient, resilient, and can be optimized to meet the multi-hazard requirements and long-term demands of high-performance structures.

Industry watchers maintain that precast concrete is used more and more to help projects meet and exceed their high-performance goals throughout design, construction, and operation. Precast Concrete Explained Concrete is a mixture of aggregates (typically sand and stone) that are bound together by a binder.

• Admixtures or modifying agents and additives are sometimes introduced to improve the characteristics of the fresh concrete, the mixing process, and/or the final hardened material.
• Precast concrete consists of concrete that is cast into specific shapes at a location other than its final in-service position.

It is produced by casting high-strength concrete in a reusable mold or form, which is then cured in a controlled environment at a specially equipped plant. Precast concrete components are reinforced with either conventional reinforcing steel, steel strands with high tensile strength, or a combination of both.

• Prestressing is a method of reinforcing where steel strands are pretensioned in the form before the concrete is cast.
• Once the concrete has cured to a specific strength, the strands are cut, or detensioned.
• Having bonded to the concrete, the strands attempt to regain their original untensioned length, adding tensile capacity to the precast member that complements concrete’s natural strength at resisting compressive forces.

This “precompression” increases the load-carrying capacity to the components and helps control cracking to specified limits allowed by the building code. As a fabricated material, precast concrete continues to evolve as new designs require new solutions and members of the design team push the boundaries of what can be achieved.

table>

/td>

Precast Walls Precast concrete envelope systems can be used in all types of projects from residential to commercial, to institutional and industrial. They can also be used in everything from low-rise to high-rise construction. Precast concrete wall panels are versatile components that can be used as architectural, structural, or combination elements within a building’s design.

Wall panels can be designed as loadbearing or non-loadbearing components, and can be used in a number of different structural configurations designed to provide moment and lateral force resistance. Non-loadbearing panels can be attached to any type of structural frame, including precast concrete, cast-in-place concrete, or steel.

They can be designed and erected in a horizontal or vertical position. There are three basic wall types, all of which can be made in essentially any shape, including: window walls, which include “closed” or four-sided fenestration openings; spandrels, which are common for parking structures and ribbon window designs; or column covers, mullions, and other customized shapes.

1. Solid, Solid precast concrete walls contain no integral insulation, with walls being typically 4 to 8 inches thick.
2. These traditional wall systems require an interior finish wall system with insulation to complete the envelope.
3. Thin shell,
4. This is a newer concept, with walls made by attaching as little as 1.5 inches of concrete to a back-up frame which, though typically comprised of metal studs, can also be produced in concrete.

The two are then joined by thermally resistant connectors. The designer can specify a layer of insulation between the exterior concrete wythe and the back-up frame. The back-up frame system allows for drywall to be attached to provide the interior finish.

Glass fiber-reinforced concrete (GFRC) precast concrete panels (typically about 1 inch thick of concrete) are another option in which a mix of concrete and glass fibers is sprayed into a mold. GFRC panels are another example of thin-shell systems, which are often used to produce intricate shapes. Thin shell systems allow for lighter weight and help reduce the size of foundations.

• Insulated sandwich wall panels, Typically including 2 inches or more of rigid insulation between two wythes of concrete, insulated sandwich wall panels provide high energy efficiency, meeting the continuous insulation requirements of ASHRAE 90.1, as well as an interior concrete wall that can be painted and used as the interior finished surface, avoiding the need for furring strips and drywall.

ol>

• Aesthetic versatility, In terms of aesthetics, precast concrete provides an almost endless array of colors and textures and allows for subtle variations through different techniques such as varying aggregate and matrix colors, size of aggregates, finishing processes, and depth of exposure.

table>

Because of precast’s initial plasticity, it may be economically designed with a combination of concave, convex, and flat sectional shapes that are difficult, if not impossible, to achieve with other materials. The medium’s plasticity further enables it to interface smoothly with glass and other modern materials, and it can also be embedded, veneered, or sculpted to resemble a wide range of finish materials, including limestone and brick, ensuring that the building blends with nearby structures, whether contemporary or historic.

Through the use of formliners, designers can affordably create supergraphics, custom aesthetic treatments, or realistic stone appearances. • Structural versatility, Precast concrete can serve as structural and cladding/envelope system simultaneously, minimizing material use and accelerating construction.

Precast concrete also provides for longer open spans with fewer columns and obstructions, as well as smaller structural cross sections through the use of high-strength concrete and prestressing. Precast hollow-core slabs and double tees, in particular, provide long, clear spans, opening interior spaces in projects from office buildings to parking structures in order to allow designers to maximize leasable or usable space within the building footprint.

Use versatility, Precast concrete both uses recyclable material, and is recyclable itself. Several common industrial byproducts, including fly ash, slag, and silica fume, which would otherwise go to landfills, can be incorporated into concrete as supplementary materials, reducing the necessary amount of cement.

/td>

Precast concrete members are unique in that they are individually engineered products that can be detached and relocated, facilitating future additions to buildings. When future additions occur, non-loadbearing panels on the end simply are disconnected from the framing, and new panels and framing are added on each side.

With the new addition in place, the original end panels can be replaced. When ultimately removed from service, precast concrete members may be reused in other applications. Because it comes apart with a minimum amount of energy and retains its original qualities, precast concrete is also friendly to downcycling, a process in which building materials are broken down.

Concrete pieces from demolished structures, for example, can be reused to protect shorelines, and recycled concrete is frequently crushed and used as fill or road base. Material Efficiency Significant efficiencies from both a construction and operational perspective are possible with precast building systems.

Site efficiency, Factory-fabricated precast concrete minimizes or eliminates dust, waste, and truck traffic at the construction site. Only the needed precast concrete elements are delivered, with the resultant decrease in vehicular activity and noise particularly beneficial in urban areas. Unlike typical cavity wall construction, often comprised of a number of different products installed by different subcontractors, precast is erected by a single Tier-1 subcontractor.

Scaffolding, lay-down space, material storage, and numerous subcontractors’ field trailers are typically not required, greatly reducing the construction site requirements and environmental impact on adjacent site areas. Because precast concrete units are normally large components, greater portions of the building are completed with each activity, creating less disruption overall.

• Optimized structural members, spans, and other components lead to minimal material waste and associated economic and environmental savings.
• Perhaps precast concrete’s most dramatic benefit, though, may be the speed with which it can be designed, cast, delivered, and erected.
• Since the prefabrication process does not rely on other critical-path activities to begin, it can be started upon approval of drawings, ensuring components are ready for erection as soon as foundation work and other site preparation are completed, giving contractors a significant head start before the site is even available, and shaving weeks or months from the schedule.

This flexibility also allows the building’s shell, whether loadbearing or cladding, to be enclosed quickly which, in turn, lets interior trades begin work earlier and reduces overall construction time. The fast enclosure decreases concerns for weather or material damage during erection, reducing the contractor’s risks and costs.

Because precast components are fabricated under factory-controlled conditions at the plant, harsh winter weather does not impact the production schedule or product quality, and often eliminates the need to add “cushions” to the timetable to accommodate unforeseen schedule creep due to delays caused by weather or site requirements.

Precast components also can be erected through the winter months to meet a tight schedule, cutting overhead costs, reducing the possibility of cold weather-related change orders, and readying the building for faster occupancy. • Energy and operational efficiency,

• Precast concrete has a high heat capacity, or the ability to slowly absorb and release large quantities of heat, contributing to a high-performance building envelope.
• Concrete’s thermal mass allows it to react very slowly to changes in outside temperature—an advantage that reduces peak heating and cooling loads and delays the time at which these loads occur.

The resulting savings can be significant—up to 30 percent of heating and cooling costs. Another factor affecting the behavior of thermal mass is internal heat gain. This includes heat generated inside the building by lights, equipment, appliances and people; and heat from the sun entering through windows.

1. Generally, during the heating season, benefits of thermal mass increase with the availability of internal heat gains.
2. During the cooling season, thermal mass exposed to the building’s occupied spaces will absorb internal gains, shifting peak cooling periods by as much as four hours, and dampening the overall cooling peak load.

Concrete exposed to the interior, not covered by insulation and gypsum wallboard, works best to absorb internal gains, saving cooling energy. Thermal bridging is also essentially non-existent with precast sandwich and thin-shell panels. Most connectors are made from composite or coated materials that do not thermally conduct.

• When combined with thermal mass and continuous insulation, precast concrete provides an extremely thermally efficient wall system.
• The color, or albedo, of precast concrete panels can be used to improve the energy-conserving features of the walls.
• Panels with high albedo, meaning they are generally lighter in color, can help reduce the urban heat-island effect.

Air infiltration, too, has significant effects on the amount of energy required to heat and cool a building, and large precast concrete panels have minimal joints, reducing uncontrolled air infiltration. Precast concrete is also an air-barrier and meets the requirements of the 2012 International Energy Conservation Code and ASHRAE 90.1.

Scalable performance, Precast construction allows for scalable performance. New energy codes and ASHRAE requirements demand varying thicknesses of continuous insulation. Precast concrete wall panels can be easily tailored to meet these requirements while avoiding many of the detailing difficulties of cavity and composite wall construction.

Low life-cycle costs, A precast façade can be designed to match the intended life of a building with minimal maintenance, providing substantial long-term savings. Precast concrete panels present a durable, aesthetically pleasing exterior surface that is virtually airtight and watertight and does not require painting.

Precast envelope systems also help minimize the total number of joints relative to other envelope systems. This helps the building remain in first class condition with minimal maintenance, ensuring its desirability to future tenants or owners. • Risk reduction,

1. Several attributes of precast concrete allow for reduced construction risk, reduced professional liability, lower construction complexity, and greater profitability.
2. As a single unit, precast systems provide a single source capability for supplying the entire exterior wall system.
3. When loadbearing precast structural floors, along with panels, are specified, the entire building structure and superstructure can be provided through one certified and reliable precast producer.

The precaster is responsible for meeting design specifications, as well as for all manufacturing and constructability issues, minimizing the number of subcontractors and attendant coordination of trades. The precaster’s staff of plant engineers is available to assist the design team on the project from the concrete mixture design to the optimum component size for production, shipping, and erecting purposes (see sidebar).

• In addition, material optimization and reduced need for detailing as described above, all work to enable the builder to do more with less, conserving resources, both material and human, and reducing construction spends.
• Designers can exert more control over the final appearance of the structures because they can view finish and range samples as well as mockup panels prior to full-scale production.

The architect and owner can visit the precast plant to monitor progress, ensuring that no surprises arise at the site. Plant production’s high quality-control standards result in tighter tolerances, too, all of which leads to a smoother, faster fit during erection that speeds construction and minimizes the need for on-site adjustments.

• Precast concrete is different from site produced concrete because it is made in a factory by highly trained and experienced personnel who apply stringent quality-control measures.
• In the factory environment, precasters are able to achieve consistency in temperature and moisture, and meet low water-cementitious ratios that are essentially not possible in field cast-in-place concrete.

Precast concrete typically possesses strengths of 5,000 psi to 7,000 psi or more, with densities that minimize moisture and bulk water permeability.

Material Resilience There is an increasing demand for today’s buildings to be resilient, not only to the ravages of time, but to climate and environmental considerations as well. This imperative means structures must not only be durable, but they must be able to withstand natural and manmade disasters, and promote life safety and healthy indoor environmental quality for building occupants.

1. Structure durability,
2. Precast concrete can promote the resilience of a structure on many levels.
3. Long service life.
4. Precast systems are typically very competitive on a first-cost basis, but the advantages shift strongly to precast’s favor when the long-term benefits are considered.
5. Precast’s long term durability is a function of the building enclosure to resist impact, break-ins, corrosion, weathering, and abrasion, making it virtually maintenance-free and resulting in preservation of the building’s original look.

Because of these factors, high-performance insulated precast concrete panels can provide a building with a long design service life—a minimum of 50 to 60 years—that outpaces other façade designs. Further, because precast concrete panels are normally large, the quantity of joints in the building cladding is reduced.

• The fewer number of joints produces fewer locations for leaks to develop due to joint failure.
• Fewer joints also reduce the life-cycle cost of replacing joint sealants and add value to the project for the client.
• Typically, the only maintenance precast concrete panels require is recaulking, with the service life of sealants dependent on the quality of the material, installation, and exposure conditions.

To minimize problems, joint sealants should annually be inspected and repaired if necessary. Architects should note, however, that quality precast production requires low water-cementitious ratios, good compaction, and curing in a controlled factory environment.

Barrier wall system. Precast concrete panels are considered air and watertight. A properly designed precast wall system is a “rain barrier” that provides better performance and requires less materials and trades than conventional cavity wall systems or rain screens.

Concrete in general provides a relatively good vapor retarder, assuming it remains crack free—achieved by standard specifications for compressive strength, etc.—and that penetrations, joints and interfaces with other materials are properly detailed. Three inches of high strength concrete constitutes a code-compliant vapor retarder.

Air entrainment is used to improve freezing and thawing resistance, particularly in severe environments. Functional resilience. Expressing a building’s ability to withstand and be quickly restored to its full functional capacity with minimal effort and resources after natural or man-made disasters, functional resilience expands the concepts of sustainability and durability.

Multi-hazard protection. High-performance precast concrete wall panels are strong enough to withstand high winds and wind-driven projectiles, hurricanes, and wildfires. The high strengths and low water-cementitious ratios used in the precast manufacturing process, combined with proper compaction imbue the material with the capacity to withstand storms and render it resistant to wind-driven rain and moist, outdoor air in hot and humid climates.

In short, concrete is impermeable to air infiltration and wind-driven rain. Architects should note, as with all envelope systems, joints between panels must be properly installed and maintained in order to provide a complete barrier system. Precast concrete walls should be allowed to breathe on at least one side and should not be covered by an impermeable material on both wall surfaces.

Research shows that appropriately designed precast concrete framing systems have a proven capacity to withstand major earthquakes, as demonstrated by recent earthquakes in Guam, United States (Richter scale 8.1); Manila, Philippines (Richter scale 7.2); and Kobe, Japan (Richter scale 6.9).

1. These events subjected precast buildings to some of nature’s deadliest forces.
2. Unlike seismic and wind loads, blast loads have an extremely short duration that can be measured in milliseconds.
3. Often, the large mass associated with the overall building response provides enough inertia so the building’s framing does not need to be strengthened to resist blast loads.

While conventional foundation systems are almost always adequate to resist the short duration reaction loads from a building’s response to blast loads, architectural precast concrete can be designed to mitigate the effects of an explosion and thereby satisfy requirements of the General Services Administration.

In fact, extensive research on seismic and blast design with the Air Force Research Laboratory has generated increased use of precast concrete in seismic zones and military and government structures, which have antiterrorism force protection requirements. • Life safety and health, A building’s resilience is also dependent on systems that ensure indoor environmental quality and protection from fire and other disasters.

Indoor environmental quality. Volatile organic compounds (VOC) are environmental hazards that degrade indoor air quality when they off-gas from new products, such as manufactured wood items like laminate and particleboard. VOCs can also combine with other chemicals in the air to form ground-level ozone.

Concrete contains low to negligible VOCs, far less than almost any other typical interior finish product. Precast concrete surfaces are often used as durable interior finish. Polished concrete floors do not require carpeting. Exposed concrete walls do not require finishing materials, eliminating particulates from sanding drywall taping seams.

Concrete is not damaged by moisture and does not provide nutrients for mold growth. Precast has low sound transmission classification and impact insulation class ratings, providing architects with inherent material qualities with which to meet increasingly more stringent indoor acoustical requirements.

1. The negligible level of VOCs in concrete construction can be further reduced by using low-VOC materials for form-release agents, curing compounds, damp-proofing materials, wall and floor coatings and primers, membranes, sealers, and water repellents.
2. Precast concrete components also work to meet standards for indoor air quality because they are delivered to the site in modules that do not require fabrication, processing, or cutting at the construction site, thereby reducing dust and airborne contaminants on site.

Passive fire resistance. A total-precast concrete system provides an effective design for minimizing fire damage and containing the effects within the smallest space possible for the longest time. Concrete is noncombustible and can contain a fire within boundaries.

As a separation wall, precast concrete helps prevent fire from spreading throughout a building or jumping from building to building. Noncombustible compartmentalization, combined with an inherently fire resistant/tolerant structural frame, provide the best combination of economics and protection that owners and users seek.

When this passive design combines with other safety measures, including sprinklers and early-warning detection systems, a balanced fire protection design is achieved. Disaster safety. Many schools and public facilities also serve as safe areas of community refuge during times of natural disasters, particularly those involving high winds such as tornadoes or hurricanes.

/td>

ul>

With the advancement of energy codes, designers are approaching envelope design differently. Building envelopes in most regions of the United States must provide continuous insulation and a continuous air barrier. Envelopes also are required to provide a vapor barrier to control condensation and indoor humidity, as well as avoid compromising the insulation system.

Precast concrete’s edge-to-edge insulation, combined with the nonconductive connectors between the interior and exterior concrete layers, can create an efficient thermal break that prevents heat and moisture from penetrating the building and eliminates thermal loss and vapor transmissions present in other wall assemblies.

With the addition of continuous insulation to precast concrete walls, which already provide an air and moisture barrier, this type of assembly effectively integrates the air, moisture, and heat management of the envelope into one efficient system. Utilizing Concrete’s Thermal Mass Potential High-performance precast concrete sandwich wall construction is an efficient way to combine thermal mass and insulation in walls.

To maximize the benefits of this, the interior side of precast concrete sandwich walls should be left exposed as the finished interior surface. Since precast concrete envelopes essentially have no thermal bridging, these attributes combined decrease indoor temperature fluctuations and enabling downsizing of HVAC systems and their associated first cost and long-term operational costs.

ASHRAE 90.1-2010 acknowledges the thermal mass benefits of concrete walls in specifying lower minimum insulation R-values and higher maximum wall U-factors for mass (concrete) wall construction in specific geographic areas. Essentially, the ASHRAE standard means that this type of assembly stores heat energy and registers better performance than the sum of its parts.

Making the Interior Wythe the Finished Interior Wall Precast sandwich wall construction can be designed to use the interior wythe of concrete as the finished interior wall. This strategy reduces the need for drywall and decreases mold potential while improving the project’s ability to take advantage of the thermal mass benefits associated with precast concrete.

A smooth steel trowelled interior concrete wall can be left bare or finished with direct-applied coverings, coatings, or paint (Note: these materials should not be vapor barriers, as to allow the concrete to breath) to minimize interior obstructions and fit-out costs. Both options provide a surface that will not be dented, punctured, corroded, rusted or otherwise damaged by heavy-duty use or equipment.

Panels can be cleaned easily, even with harsh chemicals and steam pressure, ensuring a clean, crisp, hygienic environment. Vermin and insects cannot destroy concrete because it is inedible. With proper coordination and planning, conduit runs, as well as electric and other service boxes, can be incorporated into the precast panel during production.

Envelopes as Part of the Structural System The most economical application of precast concrete wall units is as loadbearing structural-aesthetic components. Combining the insulated architectural façade with the structural system reduces the need for additional connections, and decreases the thermal bridges in an envelope system.

It also reduces material, the number of trades required to construct the wall system and thus, general conditions. The loadbearing units become an integral part of the structure, transferring loads to the foundation, including gravity loads from the floors and roof and lateral forces from the effects of wind or seismic events, and providing for the horizontal stability of the building.

1. From a design perspective, the greatest advantage of a loadbearing precast concrete system is an interior that provides large open floor plates unencumbered by perimeter columns.
2. Combining loadbearing wall panels with a precast structural floor system creates long, clear unobstructed spans with large, open bays with interior heights up to 55 feet.

In most cases, the height is restricted only by what can be transported and delivered to the site. For offices, 45 to 50 foot spans are optimal because beyond that length, bays become so deep that daylighting is compromised. With early coordination, panels can be designed with electrical conduits and outlet boxes cast into the panel, eliminating additional interior furring and material, trade overlap problems, and the need for a separate wall cavity.

table>

High-Performance Aesthetics Precast concrete has a wide aesthetic range that complements its high-performance attributes. Smooth as-cast finishes show the natural look of the concrete. Exposed-aggregate finishes, via chemical retarders and water washing, are achieved with a non-abrasive process that effectively brings out the full color, texture, and beauty of the coarse aggregate.

Sand or abrasive blasting provides all three degrees of exposure noted above, and acid-etching dissolves the surface cement paste to reveal the matrix with only a small percentage of coarse aggregate being visible. In addition, concrete can be cast against liners made of wood, steel, plaster, elastomeric, plastic, or foam plastic to create numerous shapes and patterns or to replicate natural stone materials.

Precasters can help design professionals understand how to achieve a wide range of color and texture variations in precast architectural panels within the project budget. Precast Envelope Systems: Providing High Performance High-performance buildings that satisfy a host of stringent demands are becoming the norm among today’s owners.

• Precast concrete envelope systems inherently provide many of these high-performance attributes, and can be designed to provide many others.
• Precast sandwich panels provide an effective envelope that integrates and optimizes insulation levels, shading of glazing, solar reflectivity of exterior surfaces, air and vapor barriers, and thermal mass.

When these attributes are combined with the strength, long-term durability, and multi-hazard protection inherent in the material itself, the result is a very high-performance building.

Precast Concrete for High Performance Building Envelopes

What is the risk of floor opening?

Skip to content As the leaves change colors and temperatures drop, the construction industry continues to face risks and challenges. One of the most significant hazards faced by construction workers is falls, which account for hundreds of fatalities every year.

1. Among the various causes of falls in construction, floor openings represent a major danger that deserves special attention.
2. Floor openings can be found on construction sites in various forms, such as stairwells, skylights, elevator shafts, and manholes.
3. These openings may seem harmless, but they can lead to severe injuries and even death if proper precautions are not taken.

In this article, we will explore the importance of protecting floor openings and provide practical guidance on how to prevent falls and save lives. Understanding the Risks Floor openings can pose significant risks to construction workers. A split-second misstep can result in a worker plummeting through an unprotected opening, causing severe injuries or even death.

1. Head and internal injuries are common outcomes of such accidents.
2. Recognizing the potential dangers of floor openings is crucial for maintaining a safe work environment and preventing unnecessary harm to workers.
3. OSHA Regulations The Occupational Safety and Health Administration (OSHA) has established regulations to protect workers from falls related to floor openings.

These regulations are designed to ensure that employers take necessary precautions to provide a safe work environment and required protective equipment.

• OSHA Standard 1926.500(b) defines a “hole” as a gap or void of 2 inches or more in its least dimension, in a floor, roof, or other walking/working surface.
• OSHA Standard 1926.501(b)(4) requires that employees be protected from falling through holes more than 6 feet above lower levels by personal fall arrest systems, covers, or guardrail systems erected around such holes.
• OSHA Standard 1926.501(b)(4)(ii) mandates that employees be protected from tripping or stepping into or through holes by using covers.

These regulations serve as a foundation for promoting safety on construction sites and preventing falls related to floor openings. Implementing Fall Protection Measures To reduce the risk of falls and save lives, employers should implement the following measures:

• Guardrails: Install guardrails around floor openings, such as stairwells and elevator shafts, to prevent workers from accidentally falling into them. Guardrails should be sturdy and meet OSHA requirements.
• Covers: Secure floor openings with proper covers to protect workers from tripping or stepping into them. Covers should be strong enough to withstand at least twice the weight of employees, equipment, and materials that may be imposed on them at any time.
• Personal Fall Arrest Systems (PFAS): When working near or over any uncovered opening more than 6 feet above a lower level, workers should use a PFAS to prevent falls.
• Training and Awareness: Educate workers about the dangers of floor openings and the importance of following OSHA’s fall protection standards. Encourage employees to stay alert and report any unsafe conditions immediately.

Staying Up-to-Date with OSHA Requirements OSHA’s requirements are subject to change as new information and research become available. Employers should regularly consult OSHA’s website and stay informed about any updates to fall protection regulations.

1. Conclusion Fall protection is not just about complying with OSHA regulations; it’s about protecting the lives of construction workers.
2. By understanding the risks associated with floor openings and implementing proper safety measures, employers can create a safer work environment and help prevent tragic accidents.

Remember, using the right type of fall protection can be the difference between life and death. References:

1. https://www.osha.gov/vtools/construction/falls-floor-fnl-eng-web-transcript
2. https://www.osha.gov/laws-regs/standardinterpretations/1998-11-17
3. https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.501

What does floor opening mean?

Related Definitions floor opening means an opening measuring 12 inches or more in its least dimension in any walking or working surface six feet or more above the lower level.

What distance from any edge do you require fall protection?

Height Safety PPE – A harness may be required for working at height scenarios where an operator is working within 2m of a fall edge or working 2m or more above ground level and no passive fall protection systems such have guardrails or scaffolding have been erected.

1. Any work undertaken at a height of 2 meters or more is considered “high-risk” in which case the risk of fall must be controlled or eliminated in line with the hierarchy of control measures.
2. In general, it is recommended to use a full-body harness for all general height safety work.
3. There are various harnesses designed for specific purposes, and it’s crucial to determine which one fits your job requirements.

A full-body harness typically features front and rear D rings, and adjustable straps, and is appropriate for general tradespeople, construction workers, roofing, vertical climbing, and access equipment such as an EWP. Harnesses with rescue loops on the shoulders, extra padding, and sitting attachment points are primarily designed for confined space work, rope access, window, and façade cleaning.

Fitting a harness correctly is essential to ensure maximum safety when working at height. The following are general guidelines for fitting a harness: 1. Select the appropriate size harness for the worker’s body type and weight.2. Put on the harness, making sure that all straps are untangled and properly adjusted.3.

Fasten the waist belt securely, ensuring that the D-ring is centred on the worker’s back.4. Adjust the leg straps so that they fit snugly around the worker’s thighs without being too tight or too loose.5. Tighten the shoulder straps, making sure they are properly centred and not twisted.6.

• Adjust the chest strap so that it is snug against the worker’s chest.7.
• Once the harness is fitted, inspect it thoroughly for signs of wear, damage, or other issues that could compromise its effectiveness.
• It is important to note that these are general guidelines, and each harness may have specific instructions and requirements for fitting.

Workers should always follow the manufacturer’s instructions and receive training on proper harness fitting and inspection before use. The standard for safety harnesses in Australia is AS/NZS 1891.4:2009 Industrial fall-arrest systems and devices – Part 4: Selection, use and maintenance.

This standard specifies requirements for the selection, safe use, and maintenance of industrial fall-arrest systems and devices, including harnesses, lanyards, anchor points, and connectors. It is important to ensure that any safety harness used in Australia complies with this standard to ensure maximum safety and protection for workers at height.

The lifespan of height safety PPE including harnesses and retractable lanyards is 10 years, according to AS/NZS 1981.4 – 2009. Once the ‘remove from service’ date has been reached, the equipment must be taken out of service and destroyed. If a harness & lanyard has been involved in a fall they should be immediately removed from service, even if they have not reached their ‘remove from service’ date.

What is a floor barrier?

Also known as a moisture barrier, a floor vapor barrier is typically a sheet of plastic that slows moisture from moving through a wall or subfloor. A moisture barrier is used when installing floors or walls in areas prone to dampness or excess moisture, such as basements, ceilings, or crawl spaces (source).

What is the barrier between concrete and flooring?

What is a Concrete Vapor Barrier? – A concrete vapor barrier is any material that prevents moisture from entering a concrete slab. Vapor barriers are used because while fresh concrete is poured wet, it’s not supposed to stay that way. It needs to dry and then stay dry to avoid flooring problems. Now that you know what a concrete vapor barrier is, in the article, we’ll discuss the following:

Vapor Barrier Permeability is Expressed in Perms What’s an Acceptable Degree of Vapor Barrier Permeability? Why is Too Much Moisture in Concrete a Problem? Do You Need a Vapor Barrier Under a Concrete Slab? How Thick Should a Plastic Concrete Vapor Barrier Be? What Can I Use for a Vapor Barrier Under Concrete? Where Should a Vapor Barrier Be Installed?

If you’ve ever had a problem with a basement floor (or any concrete floor), you know the kind of damage that too much moisture can cause, Moisture enters concrete in various ways, including via the ground, from humidity in the air, and through leaky plumbing that passes through a slab. Of course, the moisture was also in the original concrete mixture. There are only one-way moisture leaves concrete, though, and that’s via its surface. If you have a concrete floor in continuous contact with a source of moisture, you will have problems. This is why a vapor barrier under concrete is essential. Vapor barriers are a way to keep moisture from getting into the concrete.

What is the best moisture barrier for concrete floor?

In the 2021 edition of the International Residential Code (IRC), the guidelines were revised to recommend a minimum 10 mil vapor barrier for use under concrete slabs in residential buildings instead of a 6 mil. The American Concrete Institute (ACI) also recommends a minimum of 10 mil polyethylene or thicker for vapor retarders under concrete.

What is a good floor vapor barrier?

Choosing the Right Vapor Barrier – Americover offers a variety of concrete slab vapor barriers and tapes, all of which meet ASTM E1745 specifications. This standard ensures the poly sheeting’s resistance to vapor migration and meets industry standards for tensile strength and puncture resistance.

The most commonly used vapor barrier under concrete slabs is polyethylene (poly) plastic sheeting with a thickness of 10 mil or 15 mil. All Americover Vapor Barriers are composed of virgin polyolefin resins and offered in 10 mil, 15 mil, and 20 mil. These are high-performance materials designed to stop moisture migration and prevent gases or contaminants from infiltrating the concrete slab, flooring, and walls.

These vapor barriers can be installed over tamped earth, sand or aggregate base: simply unroll and completely cover the area receiving the slab, overlap the seams by 6 inches and seal by heat welding or with sealing tape. All exposed penetrations should also be sealed.

Jack Gloop