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In recent years, there has been a strong emphasis made in order to improve the quality of flashing around windows and doors in residential and commercial construction. When it comes to some wood-framed exterior door installations, there seems to be a double standard in regards to flashing requirements. For example, some builders/installers have made comments such as:. “We don’t have flashing requirements for exterior doors.”. “We don’t flash exterior doors because they are typically protected by a porch roof or roof overhang.”. “We provide a metal drip cap flashing over the exterior doors for waterproofing.”Some contractors follow up such comments by stating:. “We have a flashing program for window installations that we adhere to in all cases.”Although it is great that many builders are recognizing the need to establish a flashing program for window installations, this is merely not enough.
What many fail to realize, is that exterior doors posses a larger potential moisture intrusion area than the average window, and therefore, the presence of an exterior door flashing program is just as essential. An abundance of issues with exterior doors have been observed in the field, which has proven that several builders have disregarded following an exterior door flashing program. In order to illustrate the importance of this, the following stand out as some significant examples:Imagine a builder who does not flash a home’s front door entrance assuming that that a porch/roof overhang is sufficient enough protection. When the same builder installs a garage service door, the service door is not flashed other than with a typical secondary metal drip cap flashing, since this is the practice that has been mimicked from the front door installation. The problem here, is that a garage service door often has great exposure to moisture intrusion, since it generally has minimal overhead roof protection. Another example of where significant exposure to moisture intrusion can be found, is at the exterior door of a multi-unit condominium building.
Often, the building plan lays out so that many of the doors are well-protected, while other doors go unprotected. Therefore, the tendency is not to flash the doors with anything other than a drip cap at the head. Exhibit 1Exhibit 1 shows a double standard when comparing an exterior door installation to a window installation, where the door and window are installed in a protected area of the home’s exterior.
As observed, the window is fully flashed, while the exterior door does not show any flashing. Please note that the weather barrier does not count as flashing, and because there is no flashing below the threshold of this door, a metal drip cap will be installed above the door during siding installation.Additionally, the exterior door’s perimeter (where there is potential for leakage not related to flashing) is over twice that of the fully flashed window. This builder uses the same exterior door installation technique on garage service doors, which are in an unprotected, high-wall area of the homes’ exterior. Below is a picture of the garage service door in Exhibit 2. Exhibit 2 Exhibit 3The weather resistive barrier in Exhibit 3 has not been properly extended over the head flashing strip. Exhibit 4Exhibit 4 shows an exterior door in a covered patio area that is not properly flashed. An edge of this doorway is only 12 inches from wind-driven precipitation.
This presents a problem because storm moisture can easily reach this improperly flashed doorway jamb and threshold.Quality Built recommends that builders and trade contractors adopt a consistent best practice program for the installation of exterior doors, and related items that penetrate the building envelope. Consistently installing flashing in a best practice method on exterior doors will prevent an exterior door in a less protected location from creating a water intrusion problem. Exterior doors that are installed in more protected locations will benefit from a flashing system that can not only prevent the occasional water intrusion, but minimize air infiltration and insect infiltration into the building. A third-party quality assurance program can help to verify the consistent installation of flashings, as required to create a complete weather-resistive building envelope. Best Practice SolutionsA best practice flashing program should be adopted by all builders and trade contractors for the installation of exterior doors and all other items that penetrate the building envelope. This program should include mandatory flashing requirements for doors with pre-installed brick molding, or other pre-installed trim.
Typical AAMA, ASTM, NWWDA, WDMA, and manufacturer’s best practice flashing requirements should be met by this program. The steps for providing the best practice method of flashing installation at exterior doors will vary depending on the type of interface between the door and the flashing. Many exterior doors do not have nailing flanges like windows, but instead have a brick mold or other trim that creates the transition to the flashing. Quality Built’s recommendation is that the following installation steps be followed:. Install self-adhered, membrane flashing below the door threshold.
Installation of a sill pan below the door threshold is recommended. Jamb flashing should be installed on each side of the doorway. A self-adhered membrane flashing should be used. The jamb flashing should extend over the threshold flashing and extend a 6-inch minimum above the top of the doorway opening on each side. The door should then be installed with compatible caulking below the door threshold, and continuously around the back of the brick molding or trim. Appropriate manufacturer’s recommendations for door alignment and anchoring should be followed during installation. Angled metal drip cap flashing material extending over the door head trim and returning at the ends should than be installed.
A self-adhered head flashing strip should be installed across the top of the doorway and over the drip cap vertical leg.
A popular retrofit for older homes is new windows, but you may not be installing them correctly. Proper flashing is one concern.As I sit next to my aluminum framed, single paned windows that are almost fifty years old, I feel the cold, causing me to wonder why I have not replaced them yet. A few weeks ago, I discussed window replacement with a neighbor, who has been working to upgrade their home.
Last year another neighbor had changed out ll of his windows. There are many steps to energy efficiency, and window replacement is one item that tops the list for many homeowners. Replacing windows is not that hard, so the task can be a great do it yourself project; however, you have to consider the possibility of adding flashing over the window.If you have with some type of cladding like wood, you have windows that come out beyond the cladding surface with trim. Windows in homes with a brick exterior are typically recessed.
This is the case for stucco exteriors as well on most occasions. On walls with sheathing or planks, you will see the window covered by trim, or the window frame will be slightly beyond the surface of the exterior wall covering. This does not make the job of replacing the windows harder, but there is a step that can be forgotten. The photographs above were taken during a home inspection of an historic house that had new energy efficient windows installed. Notice anything different?Above one of the windows you see a piece of metal sticking out between the top of the window frame and the trim; this is the flashing. Some people refer to the required flashing as “z-flashing”, because it has a shape like a “z”.
You also have j-flashing or L-flashing. Another term is kick-out flashing.
This last term is used more for the flashing on the fascia under the roof. I have the tendency to use only the word flashing in my inspection reports, because it is simpler to understand than explaining the different methods that can be used for installing this device.Why do I need this flashing? Rain does not come straight down. During a windstorm, rain is blown onto your exterior wall, even under the roof’s overhang (soffit and fascia).
The water comes down the wall to the trim around the window. (With recessed windows, the water drops to the sill, which should be angled to move away from the home). Here is where installation methods could vary. If the trim is flush with the exterior wall, you will want the flashing to sit on top of the trim, and then come over the front face of the trim. Water that sits on the trim can damage the wood of the trim piece.
In the case of the home in the photographs, the upper trim is some distance away from the wall, so the flashing catches the water running down the wall at the top of the window, forcing it to flow away from the wall. In both cases, it is best to have part of this flashing on the wall behind the exterior cladding.
Any water that comes behind the cladding will be caught by the flashing above the window, directing it away from that flat surface of the top of the window frame.Is this flashing always necessary? There is a new window design that I have been told by builders that it does not need this flashing. The top frame of the window has two channels around the edge. The window is sealed with caulking around the edges.
Water coming down hits the top of the window frame, going into one of these channels, and then down the side of the window. I am a little concerned about this method as the house ages. If gaps arise, which allow water behind the exterior cladding, the water will run down the sheathing. This is fine, because all builders create homes to handle this situation (on brick homes, the weepholes at the bottom of the wall help expel this moisture). Will this window style help navigate water from standing at the top of the frame?
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Supposedly it does, but for me seeing is believing. Too often a manufacture can make a claim that they in good faith believes to be true, but could be hampered by how the unit was installed.
On my home inspections, I have noticed that this type of window unit does not have trim surrounding it.Although the photographs are of a home built in the 1920s, I find that some builders even today forget about this flashing. Moisture damage can happen.
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Even after a year, I have seen caulking begin to fail. The other area to check when replacing windows is the wood sill. Not all windows have sills, so it may be the bottom trim piece. Something to check before you begin installing the window, or you will be heading back to the home center for more supplies.
