RAINSCREENS ARE AWESOME
10/17/2024 - 1 MIN
Rainscreens are a simple addition to a wall system that pays big dividends in durability of your home.
A rainscreen is a layer in wall system that creates an air gap between your wall cladding (i.e. siding, brick, stone, stucco, etc) and the air and water barrier (i.e. Tyvek over wood sheathing, Zip System sheathing, etc). The air gap does a few things:
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provides a drainage space for water that gets behind your cladding to drain out
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ventilates with air for increased drying capacity
As a result, the back of the cladding and/or the face of the air and water barrier/sheathing can dry out, ultimately providing a longer lasting, more durable wall that protects against mold, rot, and structural degradation.
The air gap needs to be vented at both the top of the wall and bottom of the wall to maximize air circulation, a very important piece of the system. A rainscreen with this type of ventilation is called a ventilated rainscreen, which is not to be confused with a vented rainscreen. Vented rainscreens are only vented only at the bottom of the wall, and therefore not as effective at drying.
Most rainscreens are made of wood or plastic furring strips, or a 3D mesh. We typically use the furring strips for siding and 3D mesh products for stucco.
Nine times out of ten, builders attach siding directly to the air and water barrier with no gap (see Figure 1), which not only can compromise the siding, it makes a lot more holes (weak points) in the air and water barrier and creates fewer areas for the wall assembly to dry out. What happens when water and wood meet and it can’t dry out? Nothing good. Our advice….MIND THE GAP, EH! as Dr. Joe Tsiburek says. You’ll thank us later.
For further reading:
Figure 1. Direct method (standard method) for attaching siding over house wrap. Photo from BEMMI.
Ventilated rainscreen. Siding over wood furring strips to create an air gap, with a vent at top and bottom of wall.