Windows provide light and ventilation to our homes.They also play a significant role in meeting building and energy codes.
In this segment you will learn the all-important installation details necessary to prevent water damage, meet energy requirements, and promote efficient window operation.
There are several things to consider when purchasing new windows or replacing the old ones in your home. Ultimately the choice comes down to cost however there are several other considerations to keep in mind.
-
Energy efficiency: In the search for lower energy costs and comfort it is important to use the most energy efficient windows you can afford. Energy efficient windows are categorized by their capacity to restrict heat flow (U-Factor) reduce heat gain from the sun (solar heat gain coefficient) and restrict air leakage. Window labels also indicate how much light is allowed to enter the building. Window labels are usually
Energy Star or
NFRC (National Fenestration Rating Council).
-
Style: Modern windows come in all different shapes, sizes and even colors. Here are a few things to think about when shopping for new windows.
-
All windows have glass or glazing as it is called. Other important parts are the sashes and frames. Window frames are the structural part of the window (see graphic). Window frames are made of metal (usually aluminum) wood, PVC (vinyl) and composites. Aluminum windows are the least expensive and wood ones are usually the most expensive. Windows can be made up of any combination of these materials.
-
Another way to look at window styles is how they operate or function. Some are double hung where two independent sashes move up and down independently to open and close. Another popular style is casement windows; these open with a crank and are hinged or pivoted from the side. Awning and hopper windows hinge from the top or bottom and sliders move on rollers or tracks from side to side.
-
Warranty: While the warranty is important when windows fail it is more important to check the reputation and stability of the installation contractor to confirm they will be around in the case there is a need for service or repair sometime in the future.
Guidelines on selecting contractors are available in other documents available from the LSU AgCenter.
Windows come in two basic configurations, ones with mounting flanges and without mounting flanges. Each are installed differently. We will focus on the ones with mounting flanges. To see instructions for windows without mounting flanges visit the manufacturer’s website and download their related instructions.
Here are some best practices for installing your new windows so they will provide years of trouble-free service.The mounting flanges are there to position the window in the opening and to provide a way to seal the window to the moisture barrier. The moisture barrier is the housewrap or building paper wrapped around the building to keep unwanted water from getting in causing mold and decay.
Most windows sold to be installed in residential construction are the mounting flange type. Ones without will meet all of the requirements for residential construction building and energy codes however there is enough difference to have the ones with mounting flanges as the first choice.
The most important aspect of installing windows is to follow the manufacturer’s instructions. If the instructions that come with your new windows do not have clear and complete instructions to meet your conditions it is important to get them from somewhere else. The first place to look is in the yellow pages or on the internet and contact technical support to get instructions.
Regardless of where you get the instructions it is important to have a copy available on the job for the installers and a reference to these instructions in the contract. In addition to printed instructions, other items you should have on hand include:
-
manufacturer tech support,
-
flashing instructions,
-
codes, standards and specifications, and
-
all part of the construction documents.
Once you have a working set of instructions available for use at the jobsite and referenced in the contract the next step is to get the flashing materials. Most manufacturers refer to a document from ASTM (American Society for Testing and Materials) called E-2112-07 when specifying the flashing materials best suited to install their windows.
The basic components for installing and flashing windows include:
-
Flexible flashing, usually a self-adhesive flashing in widths from 4” to 12” used to seal the window frame to the moisture barrier.
-
Rigid flashing, used to aid in deflecting water away from the window and the window opening.
-
Sealant, often called caulk, sealants are used to fill and seal gaps in the moisture management system.
-
Shims, to help secure the window in the framed opening.
-
Fasteners, nails or screws used to fasten the window in the opening.Insulation, best for this purpose is low expansion spray foam.
There may be other materials necessary for your project and they will be identified in the instructions you have.
Before the windows are installed it is important to know the condition of the moisture barrier, also called the moisture management system or weather-resistive barrier or WRB.
The WRB is made up of building paper or housewrap used to cover the entire building, much like a protective coating. This will keep rain out and allow the walls to breathe. Since we poke many holes in this barrier it is necessary to seal the penetrations with sealants and flashings.
Key to this system is to cover all of the outside of the framed building. While there are many new materials and techniques to keep water out of buildings the one thing to always to keep in mind is to install the components of the moisture management system in weatherboard fashion. Start at the bottom and cover what is below with what comes above.
Now the windows, instructions and accessories are available it is time to get to work.
Tools
You or your installation contractor will need a few tools. A basic tool set includes a tool belt, tape measure, hammer, utility knife speed square and hammer.
This goes for most projects, if you are doing any work yourself take the time to get a decent set, good tools make the job easier. For installing windows there are a few other tools necessary:
- Levels, several sized to fit the different dimensions on your windows.
-
Caulk gun
-
Ladder, one tall enough to safely reach the top of the windows you are installing.
-
J-roller, a rolling tool commonly used by cabinet and counter top installers.
-
Tin Snips for cutting any rigid flashing
-
Cordless (or corded) screw gun for setting screws.
Optional Tools
-
Miter saw
-
Circular saw
-
Reciprocating saw
Now! We are ready to do some installing.
Two important things to check before starting are:
window manufacturers will usually specifiy how much larger the rough or framed opening should be than the actual window size. The openings should be large enough to fit the window I and leave space for insulating with spray foam, low expansion spray foam.
PLS and in plane -- The number one reason for window problems is windows being installed not plumb level and square. Check the sill is level.
Once you are satisfied the windows will fit into the opening it is easiest to place the windows around the building near where they will be installed but not in the way and where they will not get damaged or dirty.
Now is the time to have the installation instructions available if there are nay questions and than unwrap the first window.
Take the time to inspect the window for damage. Practice fit the window in the opening before applying any flashing or sealant. If any adjustments need be done it is easier now. If the widow fits easily as expected then it is time to begin the process of sealing the window to the WRB/moisture barrier.
Openings for the windows must be cut in the moisture barrier. There has been much confusion on the most effective way to do this. The current practice is to cut the opening in a modified I or upside down martini glass configuration with a flap at the top of the opening.
The basic procedure for installing windows with mounting flanges is typical to most window manufacturers, be sure you know the ones for your widows—they may vary.
Starting with a level sill, apply a piece of flashing at the bottom of the sill.
The next step is to apply sealant to the back side of the mounting flanges, or to the wall according to the instructions and place the window in the opening.
Have someone inside to check the window is centered in the opening and place one fastener in the upper right or left corner. Using a level, check for plumb and level and use a tape measure to check the diagonals.
The diagonal measurements will be the same when the window is square. Adjust as necessary and place a second fastener in the opposite corner.
Repeat the plumb and level checks as well as the diagonal measurements. Make adjustments as necessary. Have someone inside operate the window to make sure everything lines up. Then continue fastening as recommended by the manufacturer.
Once the window is set in place apply the flashings at the sides or jambs. Make sure the flashing is fully adhered to the moisture barrier by firmly rolling the J-roller over the surfaces.
Now comes the head flashing, it should cover the mounting flanges at the head and extend past the jamb flashings.
Roll the flashings one more time and then fold the moisture barrier flab down and tape the seams.
This is your window installed.
Repeat this until all of the windows are installed.
Take extra care cleaning the windows and do not use a metal blade or scraper to remove any difficult materials stuck on the glass.
Related article:
Video showing window installation.