Drainage Plane
Posted on Nov 2nd, 2009 by Doug Marsh VP, CR, CAPS, GBP | 0 Comments
Since keeping the rain and wind out of a building is so important to combating damage to the structure (poor sustainability-labor and materials redo) and air quality problems, I find it very interesting to notice new building component details before they get covered up. This new Zip Wall product (sheathing and roof deck panels with a green color), in my mind, look to be a potential problem down the line: the wall system depends on using the company's expensive tape to seal window and door flanges to the Zip Wall sheathing. Tape on top of flanges and the sheathing fails drainage plane 101. Especially behind masonry veneers tape over flanges is extremely susceptible to expansion and contraction and moisture running down the sheathing and out the weep holes. The only way you would know if the tape was coming off the sheathing is when the moisture starts showing up on the interior of the building but then, of course it is behind the brick. Shingle style lapping of the sheathing or house wrap and/or tape over flanges of windows and doors and all flashing's is critical (what's below is under whats above). Tape has appeared on the scene in the last 10+ years and it has become part of the "it's too easy to use" syndrome! For stucco applications two wraps is a good way to go: wrap number 1 on top of all flanges and flashing's and wrap number 2 (diamond lathe felt backer) over that. Although I would prefer not to use wood siding it does come up on projects so a drainage plane application is called for: apply wrap on sheathing over flanges and apply vertical 1 x 3 strips over studs to space the siding off the frame. This is the best way to go for horizontal hardiplank too.
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