(C) J Wiley, S Bliss Best Practices Flashing Details for Exterior Doors

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Door flashing & sealing:

This article describes the proper flashing details for exterior doors to avoid air leaks, rot, decay, and energy losses at doors. In this article series we discuss the selection and installation of windows and doors, following best construction and design practices for building lighting and ventilation, with attention to the impact on building heating and cooling costs, indoor air quality, and comfort of occupants.

We review the proper installation details for windows and doors, and we compare the durability of different window and door materials and types.

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Guide to Exterior Door Flashing Details

As detailed in Best Practices Guide to Residential Construction Chapter 3, BEST PRACTICES GUIDE: WINDOWS & DOORS:

Doors are flashed the same as windows on the sides and top, and similarly at the sill. Clad door frames are flashed like clad windows (see our window flashing illustrations below, Figures 3-13, Figure 3-15, Figure 3-16) and solid wood frames are flashed like traditional windows with brickmold (Figures 3-17 also below).

[Click to enlarge any image]

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Figure 3-13: Installing Flange-type WIndows Over House-Wrap

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Figure 3-15: Installing Flange-type Windows Before the House Wrap is Applied

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Figure 3-16: Installing Flange-type Windows with Felt Paper

(C) J Wiley, S Bliss

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

See WINDOWS & DOORS our home page for window and door information, and also see WINDOW TYPES - Photo Guide for a photographic guide to window and door types and architectural styles.

Figure 3-17: Installing Windows with Brickmold Trim

Unless a door is well-protected by a porch or large overhang, good pan flashing at the sill is critical to prevent water from seeping into the floor framing. Doors leading to patios and decks are particularly vulnerable to wetting around the sill from splashback and, in cold climates, from snow buildup.

Pan Flashing for Exterior Doors

Sliding door sill rot (C) Daniel Friedman

Prefab plastic door pans typically come in three sections that are fused together at the required length with solvent-based cement. Metal pans require a brake to form and should be caulked or, preferably, soldered at corners.

In fact the absence of effective flashing at this 20-year-old sliding glass door led to the need for a complete door, door jamb, and trim replacement on this Poughkeepsie home.

When the new door was installed we included a sit-built pan flashing and membrane flashing around the door for a more durable replacement.

Peel-and-stick membranes have become increasingly popular due to their ease of use and flexibility. Whether to use a metal pan, plastic pan, or peel-and stick membranes is a matter of personal preference as all work well (see Figure 3-26 below).

(C) J Wiley, S Bliss

Figure 3-26

(C) J Wiley, S Bliss

Figure 3-27

Whatever material is used, all pans should have a dam on the ends and along the inside edge. On the exterior, the pan flashing should lap over the deck or masonry flashing below. If forming a pan with peel-and-stick membrane, carry it up the sides at least 6 inches, and turn up the inside edge so it is held in place by the underlayment or finish flooring (Figure 3-27 above).

Also see 

Window and Door Resources: where to buy window and door products

As noted in Best Practices Guide to Residential Construction Chapter 3, BEST PRACTICES GUIDE: WINDOWS & DOORS:

Manufacturers of Windows & Doors

Windows and Patio Doors

Door Manufacturers & Products Guide

Industry Associations for Windows & Doors

-- Adapted and paraphrased, edited, and supplemented, with permission from Best Practices Guide to Residential Construction.


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