House wrap is one of the most important features of modern construction. House wrap is a fabric made from polyethylene fibers designed to protect a structure from drafts and moisture. Used in conjunction with special tape, house wrap seals up the small cracks and gaps that would otherwise allow air and moisture to enter the building. Today we will discuss how to install house wrap around existing windows (and doors), and why it is needed.
Why Would I Want House Wrap Around My Windows and Doors?
Because it happens so gradually, many times we don’t realize just how drafty our homes can become. Over the years we just become accustomed to our homes and get used to some rooms being a different temperature than others. Or, sometimes we just accept that drafts are part of the charm of an older home. The reality however, is that energy and therefore money, are being wasted by allowing these drafts to literally suck conditioned air from your home.
In years past, builders attempted to eliminate or reduce these drafts using roof underlayment, better known as tar paper.
The tar paper was wrapped around the entire home, or at least around doors and windows to help reduce unwanted air from entering the building. However, because tar paper was not designed for this purpose, over time it tended to dry up and crack, creating the very problem it was trying to solve.
Early in the 1980’s, in an effort to combat the energy crunch of the 1970’s manufacturers began producing building products aimed at energy conservation. Windows and doors became more energy efficient with the addition of interior insulation and double paned, low energy transfer windows. In turn, this led to better installation methods such as the use of house wrap and thermal tape around these features to retard air and moisture penetration.
Can I Install House Wrap Around an Existing Window?
Answering this question will depend on the type of exterior facade you have. The installation of house wrap around an existing window will require the removal of the facade, so those attempting this repair on masonry homes like brick and stucco will find this step extremely difficult and in many situations, infeasible. However, on homes with siding like vinyl, aluminum, hardboard, T1-11, shakes, and other forms of lap siding, the project will be relatively simple.
The goal in each scenario is to extend the house wrap 12” beyond the window frame. Wrapping the frame within 12” of the window will make installing the house wrap on the remainder of the home much easier by cutting a simple notch in the house wrap.
The steps required to install house wrap around existing windows will vary slightly from window to window, but the basic process will remain the same.
Here we will describe the common window types likely to be encountered and offer tips for how the house wrap should be applied :
Wood Counterweighted Window
Wood counterweighted windows were some of the first window designs that did not require hinges. However, these windows lacked any form of flashing and being made of wood, tended to allow leaks around the frame. Since these windows do not include a mounting fin, the house wrap and tape should extend from the rough opening, over the gap and onto the window frame. In most instances, removing any trim such as brick molding will make the job easier.
Vinyl and Aluminum Replacement Windows
Both vinyl and aluminum replacement windows are designed to be installed within the existing frame of an older window. Due to this design, replacement windows generally do not include a mounting fin and are simply attached with screws inside the existing window frame. As such, new house wrap will not extend to the actual window, but to the original window frame. If the window has brick molding surrounding it, the molding should be removed and the new house wrap installed under it.
Vinyl and Aluminum New Construction Windows
Adding house wrap to a home with new construction windows, whether vinyl or aluminum, is very simple. In most circumstances, the nails are gently removed from the nail fin one side at a time and the house wrap is slid underneath. The order is important, so the bottom should be installed first, then the sides, and lastly the top. The nail fin is then reinstalled and tape is applied over the nails and fin.
How Do I Install House Wrap Around an Existing Window?
This section will assume that the exterior facade has been removed and the sheathing on the home is accessible. As mentioned previously, installing house wrap retroactively requires removal of the exterior facade. This is why this repair is not generally recommended for homes with brick or stucco unless the absence of the house wrap has caused water damage. In this instance, the facade will require replacement anyway.
- Step 1: Remove the Siding
Generally speaking, most siding can be removed with a combination of nail pullers, hammers, and pry bars. Vinyl and aluminum siding are usually installed with galvanized roofing tacks or staples. Removing these fasteners is a matter of gentle persuasion and patience, with the goal of re-installing the siding without damage. Once the edge of the window can be seen, the house wrap can be installed.
- Step 2: Measure and Cut the House Wrap
The easiest way to measure and cut the house wrap is to cut the material into four (4) 12” strips. Next, each strip is cut to length by adding 12” to the length of the window. For example, if the window is 30” x 30”, the installer will cut four strips, 12” by 42” (30 + 12). The extra 12” is divided into two, so that an additional 6” of house wrap extends beyond the window in all four directions.
- Step 3: Install the House Wrap
Starting at the bottom, the first strip of house wrap is placed horizontally over the joint between the window frame and the rough opening and taped into place. Next, the second strip is installed vertically on either the left or right side (either is ok) and again taped into place. Then the other vertical side is done the same way, making sure to overlap the previous strip by 6”. Lastly, a strip is installed across the top of the window and the taping process is repeated. At this point the siding can be carefully re-installed.
