Short laps and a bare strip under the eaves: how to check a housewrap job before siding goes on

The owner's post on Reddit's r/Homebuilding raises two questions: are the laps too short, and is an uncovered strip below the roof acceptable? The International Residential Code requires a water-resistive barrier over the studs or sheathing of every exterior wall, and barriers other than No. 15 felt must go on according to the maker's instructions. On a Tyvek job, that makes DuPont's guide the yardstick.

DuPont's numbers are specific. Start at the bottom so each upper course sheds water onto the one below. Horizontal laps need at least 6 inches and vertical seams 6 to 12 inches, and every vertical seam gets Tyvek Tape. The bottom edge should cover the sill plate joint by 2 inches, or by 1 inch if taped or sealed, or run to the bottom of the plate on a slab. Fasteners go into studs every 6 to 18 inches, with none within 9 inches of a window head.

On the bare strip, DuPont's 2008 guide says to keep wrapping all the way up and cover the entire wall surface, unconditioned spaces included, and its warranty terms require taping or sealing roof-wall interfaces. Minnesota's amended code is blunter: the barrier has to run unbroken until it meets the bottom face of the rafter, or of the top chord on a truss roof. A gap at the top can be closed with a new strip lapped at least 6 inches over the course below and sealed along its upper edge, which DuPont allows with tape or a 1/4-inch bead of sealant 2 to 3 inches from the edge.

If the job ends in a dispute, photograph each lap with a tape measure across it, plus the top edge under the eaves, the sill line and every window head, before siding starts. DuPont requires HomeWrap to be covered within 120 days of installation.