What should be used behind the cladding on a house to protect against moisture? We know that a fully vented, wide drainage and drying space (what is often called a “rainscreen”) works well. But creating such a space can be expensive, and other, less expensive approaches often work, too.

As an industry, we’re in a period of transition and learning as we build walls with more insulation than in previous decades. However, we do know this: When we add insulation, the outside of a wall stays colder all winter. This results in less drying and more moisture in sheathing and claddings. Therefore—generally speaking—walls with more insulation need more consideration for drying than those with less. Whether a problem or failure results will depend on a list of factors, including climate, building shape and exposure, interior humidity conditions, even future maintenance—the wrong paint can cause issues, as can caulking drainage weeps closed. In this article, I’ll introduce how we address these factors when we decide how to detail different types of siding.

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