Drainage Plane Behind Vinyl Siding

Walls that dry are walls that last for a long long time.

Drainage plane behind vinyl siding.

Rainscreen between flat to wall siding and the water resistive barrier as a best practice. For single family construction james hardie recommends installing a 90 efficient drainage plane or a 3 8 inch air gap i e. Above the window is the same deal water can drain out air can flow in. Building america recommends a gap of at least 1 16 inch behind lap siding and a drainage space of inch between stucco and plastic house wraps to control liquid phase water penetration.

This space is known scientifically as a drainage plane and it is most effectively created by installing a product commonly referred to in the industry as a drainage mat. It makes its own drainage gap. Below the window air can flow up and out behind a notch in the trim board. Drainage planes building paper house wrap etc allow any moisture that does accumulate behind siding a chance to drain away harmlessly.

Since you have tyvek you re all set. So why use a drainage mat product behind your stucco cultured stone man made stone thin brick hardboard siding or other veneer. With vinyl and aluminum siding the drainage space is more pronounced and furring is not necessary. Which is like the top of the wall.

Behind vinyl siding you definitely need a water resistant barrier wrb. Ideally wood siding should be installed over furring creating a drained and vented air space between the drainage plane and wood siding. You don t need a separate air gap between the vinyl siding and the tyvek because vinyl siding is installed loosely and doesn t sit tight to the sheathing. Ideally wood siding should be installed over furring creating a drained and vented air space between the drainage plane and wood siding.

However none of these products does a great job at draining water out from behind the siding materials or allowing the back side of siding to dry out. With wood siding the drainage space is typically intermittent and depends largely on the profile of the siding. The air space between siding and sheathing should also allow humid air to escape. Siding is applied directly over the drainage mat so water can drain out and air can flow in.

With vinyl and aluminum siding the drainage space is more pronounced and furring is not necessary.