Vapor-Retarding Membranes for Back-Up Walls Redding 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 Redding.

Earl K Powers Construction
(760) 738-9622
678 Enterprise St
Escondido, CA
 
Ironwood Construction Company
(510) 524-8058
7505 Fairmount
Oakland, CA
 
Watterson Plastering
(760) 741-0306
1859 Eagle Summit Pl
Escondido, CA
 
Narco Plastering
(408) 293-2060
1719 Grant St
Santa Clara, CA
 
Delatorre Plastering
(805) 988-0865
945 Caliente Way
Oxnard, CA
 
Barraza Joe S Masonry Inc
(408) 727-1148
1490 Norman Ave
Santa Clara, CA
 
Ed'S Landscaping
(626) 793-5296
3320 Mills Ave
Glendale, CA
 
Brown Frank
(909) 882-6180
944 W 30th St
San Bernardino, CA
 
Bill'S Home Maintenance
(707) 451-4239
490 Buckeye St
Fairfield, CA
 
A Superior Chimney Inc
(818) 353-2529
1359 Opechee Way
Glendale, 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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