Contractor Tips: How to Choose and Install Windows
5 factors to consider when picking and placing windows throughout your home
Windows are a major investment. They need to bring the outside in when you want, but also have to keep the elements at bay when you don't. The options for style, function and performance can be overwhelming. Below are five things to consider before you purchase replacement windows, and tips on deciding whether to repair or replace.
Lingo to know:
Lingo to know:
- Sash: A moveable frame that holds the window glass; a double-hung window is made up of two moveable sashes
- Mull: To join two or more windows together
- Muntins: Strips of wood that divide the sash into smaller sections of glass, which are called lites
- R value: A measure of the efficiency of insulation; the higher the value, the more insulation
- Flashing: A thin layer of metal or other waterproof material that keeps water out of joints at corners and changes in material
1. Placement. With a casement window, the entire one-piece sash rotates out by twisting a handle. It can be difficult to open a double-hung window when leaning over cabinets in a kitchen, so the casement can be a good choice there. Think about the exterior implications, though. Will the open sash obstruct a path when people walk by? Do you plan to have window boxes? You don't want the window to mow down your pansies.

2. Ventilation. If you want a view but don't need ventilation in the area, a fixed window can be a good choice. Fixed windows can be combined with operable windows to save money. If your window, fixed or otherwise, is within 18 inches of the floor or near a window seat, you'll need to order tempered glass for safety.
Here, hopper-style windows are used as transoms to provide ventilation without compromising security. Before ordering windows, think about how you will install the transom above the door. Will there be a space in between, trimmed out as in this picture?
If you plan to mull the transom window directly to the top of the door, make sure your salesperson knows and provides a factory trim to cover this joint. Or better yet, have the factory mull the door and transom together. This connection can be a tricky one to make on the job.
If you plan to mull the transom window directly to the top of the door, make sure your salesperson knows and provides a factory trim to cover this joint. Or better yet, have the factory mull the door and transom together. This connection can be a tricky one to make on the job.
3. Environment. Rain, sun and temperature shifts can take their toll on windows. If you want the look of a painted wood window, consider aluminum-clad wood. There are many color choices, and the paint job will last much longer. Trim pieces like brick molding are also available in the same material, so the entire assembly is low maintenance.
Every climate is different, and the direction your window faces comes into play as well, so consult your salesperson for the best choice when it comes to efficiency. In general, you'll want a window that has two or three panes of glass with space in between. The pillow of air between the panes acts as an insulator. Gases like argon are an even better insulator. Look for a film on top of the glass that reflects the hot summer sun on the outside and keeps heat in during the winter.
If your budget allows, opt for a wood window like this one. The original wood windows in many historic homes are still going strong, while decade-old vinyl replacements are being replaced again.
4. Energy efficiency. Historic window sashes were divided into many small panes of glass because large pieces were difficult to make and expensive. If you want to re-create this look but maintain energy efficiency, the best choice is a simulated divided window. Muntins are applied on the inside and outside of the glass, with a spacer in between the two panes of glass so that the look of a true divided light is achieved — unless you look closely.
If you need to replace your windows, make them as efficient as possible, but if increasing efficiency is your goal, don't start by replacing your windows. Historic single-pane wood windows can be weatherstripped and paired with an interior or exterior storm window to achieve perfectly good R values.
5. Installation. A good window without a good installation won't last, so consider this: Whatever type of siding you have — wood, vinyl, even brick — water will get behind the siding and run down the wall sheathing behind it. So think about the path that water will take when it gets to you window.
Building wrap, like Tyvek, should be lapped over so water can't run behind the window. Flashing tape should be used to seal the window's installation flanges to the sheathing. If you are remodeling, install metal head flashing to divert water around the window and pay special attention to caulking.
Building wrap, like Tyvek, should be lapped over so water can't run behind the window. Flashing tape should be used to seal the window's installation flanges to the sheathing. If you are remodeling, install metal head flashing to divert water around the window and pay special attention to caulking.
All windows have some weight above them bearing down, so a structural header or lintel is necessary to distribute that weight around the window. If you are enlarging the size of an existing opening, have an engineer calculate what size the header or lintel needs to be. Here a large wood lintel adds character to the home. The stone sill here is an excellent choice as well — a lot of water will run down the front of your windows in a storm, and stone, unlike wood, will never rot.
The details around your window can give the install added character, but trim is not just window dressing. The trim above the window should be flashing, just like the window itself. Even your best efforts won't keep all moisture out, so be sure to leave weep holes open at the bottom of a window to let that moisture out. Caulking weep holes can quickly lead to rot.
More: Browse window photos
More: Browse window photos