Water Resistant Membrane Air Gap Under Siding

Sold as flashing tape flexible flashing and peel and stick window flashing these narrow rolls of rubberized asphalt membrane can solve many flashing problems if installed correctly.

Water resistant membrane air gap under siding.

The layer beneath the siding the water resistive barrier or wrb is what will protect the plywood or oriented strand board osb sheathing from any water that sneaks in. The tent won t leak until you touch it from the inside with your finger. Typical housewraps provide only a water resistant barrier which can trap water behind claddings. Many builders have turned to huber s zip system sheathing a type of osb with a coating of resin impregnated kraft paper.

Should wood siding necessarily have an air gap between it and the wall sheathing behind it in a cold climate. Carefully detail the area at the bottom of the wall where the sill connects to the foundation. How much of an air gap do you need. Water holdout air penetration resistance and tear resistance.

This intersection is critical. The exterior face of the foam sheathing is typically the water control layer for the assembly and we need an air gap between it and the stucco cladding to drain the rainwater penetrating the stucco downwards and outwards preventing the build up of hydrostatic pressure. 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. The argument for it that it allows inadvertent moisture from interior vapor rain etc.

In independent tests hardiewrap weather barrier outperformed its nearest competition in each of these categories. The solution is to include an air gap between the wrb and the back of the siding. Hydrogap s drainage space removes 100x more bulk water while acting as a water resistant barrier. A way to escape sounds logical but couldn t the gap become an open invitation for termites and exterior vapor as well.

Hardiewrap weather barrier is installed over the sheathing beneath the exterior siding to reduce water and air infiltration. If the weather barrier is tightly attached as in the case of a peel and stick membrane or is part of a rigid board product building scientists say as little as 1 16th gap provides a capillary break that will let liquid water drain out. It s a little like an old fashioned single wall tent. Hydrogap has a 3 layer non woven substrate to provide superior tear water and air resistance.

Once you staple or fasten a membrane to a wall and pinch it between the siding and the sheathing most membranes leak. That gap in a rain screen doesn t need to be significant just enough for water to drain and air to rise. View the test results. Same as with osb 3 8 inch.