flexiblefullpage - default
Currently Reading

Making Sure Doors Are Watertight

billboard - default
Quality Matters

Making Sure Doors Are Watertight

Mastering these basics of proper door flashing will help avoid leaks around doors and keep the installation watertight

By Richard Baker August 18, 2017
Watertight door installation
Good detailing to prevent leaky doors isn’t complicated if you keep these basic principles in mind and pay attention to the problem spots.
This article first appeared in the September 2017 issue of Pro Builder.

Manufacturers have worked hard to encourage proper door flashing, with more installer instruction, better peel-and-stick products, and flanged brickmold doors that are flashed like windows. These days, the best door installers obsess over flashing details. Even so, we still see lots of poor detailing. Even if the result is just a minor leak, today’s high-performance wall systems have less drying potential. This means that small leaks can lead to big problems.


A Watertight Door Installation Starts With Good Detailing 

Good detailing isn’t complicated if you keep some basic principles in mind and pay attention to the problem spots:

  • Improper integration of flashing with the drainage plane
  • Doors without sill pans
  • Missing drip caps over the door

Incorporating a flange or nailing fin on entry and patio doors is becoming more common—for good reason. The flange allows doors to be flashed and integrated with the drainage plane in the same way a flanged window is integrated. But improper sequencing of peel-and-stick flashing is shockingly common, with upside-down laps that rely on the adhesive for long-term waterproofing, a job it’s not made for. Flashing, like siding and roofing, must be lapped in order to shed water and work effectively in creating a watertight install.

Prepping the substrate and rolling the tape into place ensures it will stay put over time. Good long-term adhesion requires that the substrate (the weather-resistive barrier) be clean and dry, and that the tape be firmly seated during installation. Smoothing the tape into place by hand doesn’t create enough seating pressure; it needs to be pressed into place with a rubber J-roller. And water will eventually get past the cladding, at which point the flashing will be called on to keep it out of the structure.


Door details for a watertight installation


Both sill pans and drip caps are crucial for preventing water infiltration ensuring the installation stays watertight. Sill pans were traditionally fabricated from metal, but today there are easier, less expensive options. One is to fabricate the pan from a length of stretchable flashing: Lay the flashing over a piece of bevel siding nailed to the base of the opening to create a drainage slope, and stretch the flashing tape around the corners at the base of the opening. Another option is a three-piece plastic pan. These products include corner pieces with wings that wrap around the sides and bottom of the opening. Be sure to seal the overlaps between the pieces with the manufacturer’s recommended adhesive—generic silicone will leak over time. Drip caps are cheap insurance, especially in areas that get wind-driven rain. Many advise installing them on any exterior door unprotected by an overhang, but they should really be used on all exterior doors.

Even builders who train their crews on proper flashing techniques may encounter problems if they subcontract the door installation to the wrong crew; be sure to use crews that have been trained and certified by the particular door manufacturer.


Key Details for Installing Doors That Have a Flange or Nailing Fin

When installing a door with a flange or nailing fin, check for the following key details to ensure you get a watertight installation:

Cut the WRB

I-cut the weather-resistive barrier at the opening. Fold the sides into the opening and staple them in place. Make diagonal cuts in the WRB at the top of the opening on each side. Fold the flap up and tape it into place.

Install the sill pan

If it’s a three-piece rigid pan, lay it over three beads of construction adhesive and seal laps between the pieces with the manufacturer’s recommended sealant.

Hang the door

Install the nailing flanges against the WRB and back-caulk with a quality ASTM C920-compliant sealant. Check that the door is square in the opening. Fasten in place.

Apply the tape

Apply flashing tape to the vertical flanges first, extending the tape about 2 inches past the top and bottom of the opening. Install the drip cap at the top of the door and seal the top edge with flashing tape, extending the tape on both sides. Roll the tape firmly into place with a rubber roller. Then fold the WRB flap back down and put tape over the diagonal cuts.

Richard Baker is program manager of the Builder Solutions Team at IBACOS.


leaderboard2 - default

Related Stories

Quality Matters

5 Ways to Silence Squeaky Floors

Take these tips to heart to deliver quiet floors and satisfied homeowners

Quality Matters

Tips for Placing HVAC Ducts in Conditioned Space

See how putting HVAC ducts inside conditioned space in a home benefits both the builder and the homeowner

Quality Matters

Don't Underestimate the Importance of Roofing Underlayment

Regardless of which product you choose to use, installing a roofing underlayment will help ensure the roof system withstands the elements and the home stays dry

boombox1 -
native1 - default
halfpage2 -

More in Category

Home builders can maximize efficiencies gained through simplification and standardization by automating both on-site and back-office operations 

Delaware-based Schell Brothers, our 2023 Builder of the Year, brings a refreshing approach to delivering homes and measuring success with an overriding mission of happiness

NAHB Chairman's Message: In a challenging business environment for home builders, and with higher housing costs for families, the National Association of Home Builders is working to help home builders better meet the nation's housing needs

native2 - default
halfpage1 -

Create an account

By creating an account, you agree to Pro Builder's terms of service and privacy policy.

Daily Feed Newsletter

Get Pro Builder in your inbox

Each day, Pro Builder's editors assemble the latest breaking industry news, hottest trends, and most relevant research, delivered to your inbox.

Save the stories you care about

Lorem ipsum dolor sit amet lorem ipsum dolor sit amet lorem ipsum dolor sit amet.

The bookmark icon allows you to save any story to your account to read it later
Tap it once to save, and tap it again to unsave

It looks like you’re using an ad-blocker!

Pro Builder is an advertisting supported site and we noticed you have ad-blocking enabled in your browser. There are two ways you can keep reading:

Disable your ad-blocker
Disable now
Subscribe to Pro Builder
Already a member? Sign in
Become a Member

Subscribe to Pro Builder for unlimited access

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.