moisture in lightweight structural concrete roof decks

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Moisture in Lightweight Structural Concrete Roof Decks

lightweight structural concrete roof decks and encourages you to notify NRCA’s Technical Services Section about moisture-related problems regarding lightweight structural concrete roof decks. Also, we encourage you to share with us any ASTM F2170 testing, relative humidity or moisture content data developed for projects you encounter.

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Moisture in concrete roof decks Professional Roofing ...

Sep 01, 2017  The issue of moisture in concrete roof decks is not new. Since 2009, NRCA has received numerous reports of moisture-related problems with roof systems installed on concrete roof decks—both lightweight structural and normal-weight structural concrete. Reported problems include roof system moisture accumulation, adhesion loss, adhesive issues ...

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CONCRETE LIGHTWEIGHT STRUCTURAL CONCRETE

Lightweight structural concrete(70-120 pcf density) used historically was for flooring; however, more recent trendinclude using lightweight structural concretes for roof deck construction. Lightweight structural concrete contains porous aggregates (expanded shale, clay and slate) that absorb up to 20% water by weight. This additional water must ...

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Moisture in new concrete roof decks - Construction Specifier

Oct 06, 2017  However, challenges related to moisture still persist. When a normal-weight structural concrete roof deck is poured (i.e. cast) in place, it contains a high level of water. However, when a lightweight structural concrete (LWSC) roof deck is poured in place, it uses significantly more water.

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Moisture in Concrete Roof Decks

Moisture in Concrete Roof Decks March 12, 2021 AIA Baton Rouge 11 Trial ASTM F2170 tests Existing lightweight structural concrete roof decks Roof 1 Roof 2 Roof 3 Roof age (yrs) 477 Area (ft2) 13,200 23,840 14,760 Thickness (in.) 6.5 7.5 7.3 No.

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Concrete Lightweight Structural Concrete Moisture

Normal Weight Structural Concrete vs. Lightweight Structural Concrete . Historically, normal weight structural concrete (145155 pcf density) has been used for roof - decks. These concrete mixtures contain solid aggregates (sand and gravel) that absorb less than 2% moisture by weight. Lightweight structural concrete (70-120 pcf density) is routinely

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CONCRETE LIGHTWEIGHT STRUCTURAL CONCRETE

Lightweight structural concrete(70-120 pcf density) used historically was for flooring; however, more recent trendinclude using lightweight structural concretes for roof deck construction. Lightweight structural concrete contains porous aggregates (expanded shale, clay and slate) that absorb up to 20% water by weight. This additional water must ...

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Better Understand Why the Combination of Moisture and ...

Jul 27, 2016  As noted, lightweight structural concrete contains substantially more moisture in the mix than normal-weight structural concrete. NRCA reports the following problems associated with the moisture present in lightweight structural concrete roof decks: Vapor from the concrete roof deck condenses in or beneath a roof system.

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Moisture Issues in Concrete Roof Decks - Cotney Attorneys ...

The National Roofing Contractors Association (NRCA) has stated that they have received, and continue to do so, a significant number of reports regarding problems created by moisture in concrete roof decks. Both normal-weight structural concrete and lightweight structural concrete contain additional water that is added to ensure the concrete ...

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Moisture in Concrete Decks - Western States Roofing ...

Increased use of lightweight structural concrete, with its pre-wetted aggregates, contributes additional moisture to concrete that further extends a concrete deck's drying period. In addition, roof deck design has changed. Cast-in-place concrete roof deck design may now include composite construction with the steel forms (metal deck) left in place.

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Wet Concrete Roof Decks Spawn a Rise in Litigation in 2017 ...

May 21, 2017  Given the severity of moisture damage to roofs and the recent warnings against roofing over concrete decks, one way to avoid it is to stop using lightweight structural concrete altogether. Opting instead for normal weight concrete means using

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Moisture in new concrete roof decks - Page 4 of 4 ...

Oct 06, 2017  However, litigation initiated by property owners over roof system failures caused by concrete deck-sourced moisture can no longer be ignored. By 2011, several research papers had been introduced at the International Roofing Symposium concerning roofing over new concrete decks. “Currently, we have a pile of legal cases in our files.

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STRUCTURE magazine Is Lightweight Concrete All Wet?

For the purposes of this article, we are considering only structural lightweight concrete: a mixture of portland cement, water, fine (sand) aggregates, and expanded clay, shale, or slate coarse aggregates. While normal-weight concrete mixes typically weigh 145 to 155 pcf, lightweight concrete typically weighs 110 to 115 pcf.

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Moisture+Concrete = Troublesome Combination Commercial ...

Dec 31, 2016  It is NRCA’s opinion that the risks of moisture-related problems associated with lightweight structural concrete roof decks outweigh the benefits. Should lightweight structural concrete be used, the NRCA recommends designers clearly state the concrete’s drying parameters, and that ASTM F2170 be used for this purpose.

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MRCA Bulletin: Moisture in New Concrete Roof Decks ...

Background: Latent moisture in new concrete roof decks has been an issue in the roofing industry for some time. Initially the issue was thought only to be with light weight structural concrete [see MRCA Technical Bulletin 2011-1 STRUCTURAL LIGHTWEIGHT CONCRETE ROOF DECKS]. However, recent research within the roofing industry raises concerns on ...

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Wet Concrete can Ruin a Good Design: Insights to Cement ...

"Moisture in concrete is only an issue with lightweight structural concrete." As the industry began to pay attention to increased reports of moisture related issues with roofs installed over new concrete roof decks in the 2000's, it was noted that many of these roof failures were primarily over lightweight structural concrete roof decks.

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Concrete Moisture and Roofing - Concrete Moisture Test Spec

Moisture levels in any concrete slab are affected by a number of conditions and therefore a final drying time cannot be predicted with any certainty outside of accurate moisture testing. Most concrete roof decks make use of lightweight concrete mixes; a big benefit to the load weight of the structure, but a drawback in terms of accurately ...

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What You Should Know About Your Cement Roof Deck - NIR ...

May 27, 2014  Recent F2170 probe tests on 2 year and 7 year old structural lightweight concrete roof decks yielded relative humidity readings in the 90 – 98% range. These roofs used bead adhesives to construct the roof assembly.

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Concrete Lightweight Structural Concrete Moisture

Normal Weight Structural Concrete vs. Lightweight Structural Concrete . Historically, normal weight structural concrete (145155 pcf density) has been used for roof - decks. These concrete mixtures contain solid aggregates (sand and gravel) that absorb less than 2% moisture by weight. Lightweight structural concrete (70-120 pcf density) is routinely

Get price

Moisture Issues in Concrete Roof Decks - Cotney Attorneys ...

The National Roofing Contractors Association (NRCA) has stated that they have received, and continue to do so, a significant number of reports regarding problems created by moisture in concrete roof decks. Both normal-weight structural concrete and lightweight structural concrete contain additional water that is added to ensure the concrete ...

Get price

Moisture Concerns - SPRI

structural concrete roof decks. There is the potential for the occurrence of fastener and steel plate corrosion due to the presence of elevated moisture levels. FM Global FM Global has not specifically addressed the moisture in lightweight structural concrete issues:

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Moisture in Concrete Decks - Western States Roofing ...

Increased use of lightweight structural concrete, with its pre-wetted aggregates, contributes additional moisture to concrete that further extends a concrete deck's drying period. In addition, roof deck design has changed. Cast-in-place concrete roof deck design may now include composite construction with the steel forms (metal deck) left in place.

Get price

STRUCTURE magazine Is Lightweight Concrete All Wet?

For the purposes of this article, we are considering only structural lightweight concrete: a mixture of portland cement, water, fine (sand) aggregates, and expanded clay, shale, or slate coarse aggregates. While normal-weight concrete mixes typically weigh 145 to 155 pcf, lightweight concrete typically weighs 110 to 115 pcf.

Get price

Wet Concrete can Ruin a Good Design: Insights to Cement ...

"Moisture in concrete is only an issue with lightweight structural concrete." As the industry began to pay attention to increased reports of moisture related issues with roofs installed over new concrete roof decks in the 2000's, it was noted that many of these roof failures were primarily over lightweight structural concrete roof decks.

Get price

Structural Roof Deck - USG

Choose USG Structural Panel Concrete Roof Deck for a dry construction method that avoids moisture related risks inherent in poured concrete roof decks. Consult With Our Experts Fill out the form below and we will be in contact with you shortly.

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What You Should Know About Your Cement Roof Deck - NIR ...

May 27, 2014  Recent F2170 probe tests on 2 year and 7 year old structural lightweight concrete roof decks yielded relative humidity readings in the 90 – 98% range. These roofs used bead adhesives to construct the roof assembly.

Get price

Lightweight insulating concrete for floors and roof decks

Lightweight insulating concrete for floors and roof decks Figure 1. The full spectrum of lightweight concretes. Low density mixes discussed in this article (shaded band at left) offer best insulating properties. Chart adapted from ACI 213 report “Guide for Structural Lightweight Aggregate Concrete,”

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Introducing Duro-Guard™ EPS Fan Fold CONCRETE ROOF

Lightweight Structural Concrete (LWSC) (85-110 lb/ft3) – Cast or poured in place over a metal deck that is not removed. Metal decks should be vented in order to facilitate faster drying of the concrete deck.

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ChannelDry Roof Assembly for Lightweight Structural ...

Roof Deck Criteria and Preparation . a. Roofing Assembly described herein intended for use on newly poured structural concrete decks (normal and lightweight) once they have reached their designed structural strength. b. Surface imperfections, fins or cracks, must be documented and reportedto the specifier, general contractor and

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What Are the Different Types of Concrete Roof Decks ...

Sep 26, 2011  Structural Concrete Deck – A cast-in-place concrete deck serves as an integral part of the structure and is designed to carry heavy loads.Normal weight concrete is typically used for cast-in-place construction. Beneath the roof cover, structural concrete roof decks are commonly topside insulated using adhered insulation panels or cast-in-place lightweight insulating concrete.

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Reroofing Over a Wet Concrete Substrate

Since the roof deck on the 1970 building is structural concrete, the severe leaks manifested themselves at . openings in the concrete, mainly at roof drains. However, eflorescence and build-up of salt crystals deposits, ranging from 1 to 12 inches in length, had developed on the underside of the concrete deck, indicating that the concrete deck ...

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Concrete Decks Drying Times - pmgcompanies

Sep 08, 2014  Risks of Fresh Concrete Decks and Concrete Drying Times. The main issue our industry has regarding water and moisture in concrete is there is not a good, practical, consistent and viable test to determine the moisture content or relative humidity of a concrete roof deck.

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