Let’s say you’re building a house with plywood or OSB sheathing. You plan to install 2 or 4 inches of rigid foam on the exterior of the wall sheathing, followed by vertical rainscreen strapping and siding. Where does the housewrap go? Depending on who you talk to, you get two different answers: It goes between the rigid foam and the vertical strapping, or It goes between the sheathing and the rigid foam.