Do foam-sheathed walls also need housewrap? There’s no simple answer to the question. It is possible to use foam sheathing as a water-resistive barrier (WRB). However, those who choose this route should know: Some brands of foam have been approved for use as a WRB, while others have not. Even if you choose a code-approved foam, you can run afoul of your local building inspector if you don't follow strict fastening and seam-sealing details.