3: Incomplete Coverage
Manufacturers often require that housewrap be overlapped approximately 12 inches at corners and, of course, sealed with an acrylic-backed tape. Often when installers roll on the WRB at inside corners, it is not tight to the inside wall, resulting in a small radius space between the WRB and sheathing. The cladding contractor then has to slit the WRB to install the cladding, which leaves a water-entry point. The rips and gaps pictured in Image 9 will allow water flowing behind the cladding to leak into the wall at the corners. The large gaps in the WRB at the roof-wall intersection in Image 10 certainly will lead to a failure. Housewraps should cover walls completely and be properly lapped to shed water. WRBs often are poorly installed at roof-wall intersections.
4: Wall Penetrations
Contractors should inspect housewraps for complete coverage to ensure all wall penetrations are flashed properly. For example, there is no flashing around the pipes coming through the wall in Image 11. It would be very easy
for water to run down the pipes and flow directly into the wall. Image 12 shows poor detailing at the electricmeter base, which surely will lead to leaks. It only takes minutes for wall components to get wet, but it takes days, weeks or months for them to dry. If the wetting rate exceeds the drying rate, mold and decay can occur.
In addition, cutting holes that are larger than necessary (Image 13) to accommodate penetrations defeats the purpose of housewraps. The proper cutting technique is to cut slits in the wrap that are just large enough to allow for properly shingled flashing. Slide the penetration through the cut, and seal around the penetration with an approved tape or a peel-andstick flashing before securing the face plate. Image 14 shows a prefabricated flashing device that stretches around the pipe and seals it.
5: Proper Fastening
Manufacturers offer recommendations for proper fastening of housewraps for a reason. In addition to their recommendations, it’s a good idea to use wrap caps instead of staples for better sealing. Every staple through a WRB is a potential water leak. Image 15 illustrates over-fastening using staples.
There is an enormous amount of confusion in the field about the correct way to flash windows and doors. The No. 1 problem I see relates to flashing sequence.
6: Poor Window and Door Flashing
Window and door installations in remodels can be complicated. Windows and doors are holes in buildings that create hundreds of linear feet of cracks where water can easily penetrate. Most water leaks occur at windows and doors because of improper flashing. There is an enormous amount of confusion in the field about the correct way to flash windows and doors. The No. 1 problem I see relates to flashing sequence. It is important for installers to follow ASTM E2112 and the window or door manufacturer’s flashing instructions. The following is the proper sequencing to install a window or door flashing:
- Step 1: When the WRB is a wrap, it should be installed before the window or door. Image 16 illustrate a proper installation while Image 17 is improper. Begin with a sill flashing that covers the rough sill and has a bottom flap that laps over the top of the housewrap. This will ensure any water that leaks through the window/door drains out over the WRB.
- Step 2: Sealant should be applied at the head and jamb areas. Then the window/door can be installed. Jamb flashing can go in after the win-dow has been installed. It should lap over the window/door flange to prevent wind-driven water from getting past the window/door into the rough opening.
- Step 3: Install head flashing from the nail fin at the window/door head onto the wall sheathing, which is illustrated in Image 18. Reinstall the housewrap over the head flashing.
7: Improper Head Flashing and Sealants
Image 19 depicts what water running down a wall “sees” as it approaches the head of the window. This reinforces how important it is to properly seal and flash at the window head. Sealant alone won’t keep water out. If the sealant ever separates and fails, there is an entry point for water. Always use compatible sealants and flashing.
The head flashing on the window in Image 20 is reverse lapped over the housewrap. Before applying the head flashing, a flap needs to be cut in the housewrap so the head flashing can adhere directly from the nail fin at the window
head onto the wall sheathing.
It pays to install materials correctly the first time. Your success does not depend on how much money you make; it depends on how much money you get to keep. Controlling callback costs starts with taking a whole-system approach to water management. Ensure crews are well trained and have detailed checklists to follow that address each step to achieving proper moisture management.