Vapor-Retarding Membranes for Back-Up Walls Bakersfield CA

Applying a rubberized asphalt membrane over the surface of the concrete masonry would make a more effective vapor-retarding membrane than would an application of an asphaltic paint in Bakersfield.

Bel-Air Exteriors
(818) 787-3200
7100 De Celis Pl
Van Nuys, CA
 
Royce Nalls Masonry
(559) 733-8559
29715 Road 158
Visalia, CA
 
All About Plastering Inc
(510) 886-6575
22634 2nd St
Hayward, CA
 
Pioneer Masonry
(562) 925-4345
PO Box 18715
Long Beach, CA
 
Sac Plaster and Design Inc
(916) 685-7379
9370 Winding River Way
Elk Grove, CA
 
Western Plastering
(650) 994-4724
99 Ashland Dr
Daly City, CA
 
Brown Frank
(909) 882-6180
944 W 30th St
San Bernardino, CA
 
Evans & Son Masonry
(925) 778-3887
904 Barmouth Ct
Antioch, CA
 
Aladdin Mobile Home Remolding & Repair
(760) 746-1000
324 E Valley Pkwy
Escondido, CA
 
Watterson Plastering
(760) 741-0306
1859 Eagle Summit Pl
Escondido, CA
 

Vapor-Retarding Membranes for Back-Up Walls

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Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: November 1, 1999

I have heard people recommending asphalt coatings for the exterior face of the concrete masonry back-up wall in cavity wall construction to act as a vapor-retarding membrane. This is particularly true with an exterior wythe of glazed brick. If the intent is to create a vapor-retarding membrane on the surface of the block, wouldn't it be better to use an impervious sheet membrane, such as rubberized asphalt? The surface of the concrete masonry is typically very rough, and an asphalt coating would typically contain pinholes.

Applying a rubberized asphalt membrane over the surface of the concrete masonry would make a more effective vapor-retarding membrane than would an application of an asphaltic paint. However, before applying any coating, you must ask yourself whether this is the proper place for a vapor-retarding membrane. A vapor-retarding membrane should be on the warm side of the insulation. Therefore, over a large portion of the United States, the heating season dictates that the vapor barrier be on the interior side of the insulation. For insulated cavity walls, this would be the exterior surface of the concrete masonry backup wythe. However, when insulation is not placed in the cavity, it would typically be either within the cells of the masonry backup or on the interior surface of the concrete masonry.

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