Rainscreen questions
New build, zone 2… Using Zip system, maybe Zip-R and making sure a good job of air sealing the Zip sheathing and all wall penetrations is done. Most of the house is brick veneer (bricks are 3-3/4″ front-to-back) with a 5-1/2″ brick ledge, which will be reduced by the overhang of the Zip or Zip-R sheathing. HardiPlank will be used on gable ends and a couple of other exterior wall surfaces.
Local exterior sheathing for custom homes is 7/16″ OSB sheathing, covered by Tyvek-style house wrap, with little regard for air sealing. This is for both brick veneer and HardiePlank siding.
Rainscreens are never used around here, even though we get almost 60″ of rain per year, mostly during Spring and Fall. HardiePlank siding is nailed directly to sheathing with no furring strips (with house wrap between).
So the main difference between my build and other local builds is that mine will be tight compared to the others, due to Zip system and attention to air sealing. Does that make it more important that we use a rainscreen? If yes, is it as important to use it behind the brick veneer as the HardiePlank siding?
Thanks,
Ira
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Replies
Ira,
Brick veneer was the original rain-screen. It is always installed with a drainage cavity between the sheathing and the brick, and it's very important that the gap remain clear of mortar and debris. Depending on your climate brick veneer can still be problematic from a moisture point of view, because it is a reservoir cladding. That is to say it absorbs moisture, and the moisture can be driven into the walls by inward vp0ur drive.
It's not much how tight your house is that dictates whether you need a rain-screen behind your cement siding. It's a good idea in all but the driest climates. Whether builders usually do it where you are probably isn't a good indication of whether it's necessary either. No one used rain-screens anywhere until relatively recently.