New Home Window Planning

If you read this - I guarantee you will be less likely to make a mistake you can’t easily change later.

Nelson Coupland

Windows can be the most expensive item that go into a home, but is something that most people do not give the consideration they should. It is shocking how many people are not happy with their original window purchase within the first two to five years. We have changed numerous windows under five years old and even some that have had Energy Star certification.

I have 30 years of helping people with their new construction plans. There are a number of things that I'd urge you to consider. This brief is to help builders and clients who are designing their own home.

Window frame thickness perimetering the glass.
The width of the window frame of:

An operator window has 3 ½” of vinyl around the perimeter plus the width of the Brick mould. (+BM)
A picture window LPF (low profile fixed) is approx 2” around the perimeter of the glass (+BM)
A fixed sash or HPF (high profile fixed) is again around 3 ½” around the perimeter (+BM)

What this means to you is:

An operator or a fixed sash (HPF) that has an OSM (outside measurement of window frame not counting the BM) of 30” wide has a visible glass width of 23”. If you make a combination window (joining one operator to a fixed sash) the result is a post between glass-to-glass of 7” wide. When selecting designs, be aware that extremely heavy mullion posts may bother your viewing. Combination windows can have this post running either vertically or horizontally (and in some cases both on very large multiple unit combinations).
A picture window that has an OSM (outside measurement of window frame not counting the BM) 30” wide has a visible glass of approx 26”. If you make a combination window with a picture beside operator, the mullion post will be approx 5 ½” thick. With a combination window that is a 50/50 split with both frames having the same OSM (outside measurement of window frame not counting the BM) the glass which is the most seen or eye catching will appear 3” smaller on the operator side or 3” bigger on the picture window side. Because of this out of balance effect, it can look better if you make the OSM width of the picture window considerably wider than that of the operator side. An intentional out-of-balance as a 1/3, 2/3 look or a 40/60 is visually more appealing. If you have a picture window beside a picture window, the mullion will only be about 4” thick. All the drawings I have seen from architects, draft persons, or home drawing computer software show all the windows as drawn with a 2” frame. These drawings do not truly represent the actual size and or the way they will look. Then, if you choose to put in grills, it can create design issues when you start working with different sizes of frames and glass.

Window sizes for bedrooms in consideration of fire escape, ventilation control and cleaning:

Building codes state that for a window to have legal egress capability, the occupant has to be able to create an unobstructed opening with no less than 542 sq. in. of opening while maintaining no less than 15” of unobstructed opening in either direction.
A window can be built with an egress hinge and achieve the 15” of width in a 22” OSM width frame, but the OSM frame height would have to be 41”. The other negative to this egress hinge is you will not be able to get any ventilation air coming through the hinge side no matter how wide you open it and you won’t have any opportunity to reach out the hinge side to clean the outboard panel of glass, which means you have to go outside and possibly up ladders to clean the outside glass.
In the same OSM height of window you can use a casement window with a standard hinge that will give you both ventilation on the hinge side as well as the ability to clean the outside glass from inside the home without having to take out the glass or go outside. The standard hinge moves the edge of the sash away from the corner 4” as it opens giving you the ability to get both air and a normal sized arm through for cleaning on the hinged side. This means the OSM of frame on the standard hinge casement has to be no less than 26” wide.
We don’t recommend casement windows OSM wider than 32” even though 36” have been done. To calculate the proper size for legal egress take the OSM width and subtract 6 ¾” if using an egress hinge, (egress hinge doesn’t allow hinge side ventilation or exterior glass cleaning) or subtract 10 ¾” from the OSM width if using a standard hinge (standard hinge does provide side ventilation and exterior glass cleaning). Now take the 542 (legal egress square inches) and divide by the result of the OSM width after the appropriate reduction based upon desired hinge. From the result of that calculation, you then add 5 3/8” to obtain the minimum OSM height requirement.
Hardware companies do not like having casement windows wider than they are tall for the mechanics of the hardware - but sometimes it is unavoidable, such as in basements where egress is required. A basement casement window with an egress hinge OSM could be 32” x 27”. In the window industry, widths are always listed first followed by the height. As much as one can get away with this size and shape we would still prefer a window measurement where the first measurement, the width, would be less then the second or height measurement.
Awning windows are not recognized as a legal egress window, because an explanation is necessary as to how to disconnect the arms that push out the sash to allow escape in event of fire. Even though in some cases, an awning window with the arms disconnected will provide more room and an easier fire escape than that of a casement window. Our awning windows are designed with a plastic break away clip to release the sash from the arms and with the ease of opening the obstruction created by the sash would not be a problem to get by. Legally, unless you can get permission from the justice department it would still not be viewed as legal egress.
Sliding windows that create the correct size of opening requirements are recognized as legal egress. But if the homeowner maintains Health Canada’s recommended humidity levels of no less than 30% Relative Humidity (RH), even the very best insulating sliders will be frozen shut once the outside temperature drops to –25C. This will not provide any escape. We do not recommend the use of any window system that has a U value higher than 1.1 in our climatic zone. We suggest you should always try to get the lowest U value possible while still paying attention to the physical testing results for a minimum of an A3, B7, and C5 rating. There is no sense in purchasing a window with a good Energy Star rating that has not been designed well enough to ensure product longevity, maintainability and serviceability.

Window sizing:
Window sizing is important not only due to cost factoring but also due to light, view, ventilation, cleaning and maintenance.

The sealed units used in the manufacture of windows have certain turnover points. There is a minimum charge for 4 square feet of SU (sealed units). If a SU goes over 16 sq. ft. it automatically jumps to heavier glass and drives up the price. Again the thickness and price jumps up again if the SU goes over 30 sq. ft.
As you go to heavier glass you also lose a very small amount of the finite amount of airspace between the glass that is available on a machined vinyl window, which can have an effect available insulation levels.
Every time you add another piece of glass or specialty coating there is a certain amount of loss of visible light loss. The amount of light loss is a fair tradeoff for the vast improvement of product performance you'll get with a coated triple pane.
When designing your window package, consider what the room is used for and the angle of view from sitting or standing etc.. Think about your angle of view when normally standing, sitting upright on a firm chair, or sitting low in a soft cushy chair. Make sure your windows are low enough for view but not too low in the wall or privacy, performance or cost.
There is a tendency to put in too many and too large windows in bedrooms. The little sitting areas in bedrooms are seldom used. The majority of time spent in the bedroom is sleeping and most people don’t want excessive light in the early morning. A large walk-in closet is nice when they can double as a dressing room, which you may want light, but the windows should be high enough to provide privacy. The one thing to keep in mind with bedroom windows is the egress or fire escape capability.
Ventilation is nice for natural airflow, but a ventilating window is a lot more expensive and has less natural light and view in comparison to an equal sized LPF picture window. Most new homes are now being built with central air conditioning and, in some cases with air-to-air heat recovery air exchangers. Regardless, you will need opening windows in bedrooms for fire escape unless you have an exit door to the outside. Ventilating windows in kitchens are handy to rid smoke from burnt toast etc.

Five reasons to open a window:

To create a cooling draft. With new technology available, windows can keep your house from getting hot in the summer the same way we can keep your house warmer in the winter. To experience a cooing draft, two strategically placed windows can ventilate a large area without the added expense of opening all windows. Air is fluid and will follow the path of the least resistance and take the most direct line.
To exhaust to get rid of smoke, odour, high humidity or heat. These are common concerns in kitchens, bathrooms and laundry rooms where you can have short-term increases in these types of air qualities.
Fire escape specifically in bedrooms.
To have the ability to clean the outside of the glass from inside the home. This is important on higher-level windows so people don’t need to go up extension ladders to clean windows.
To have the ability to call out to someone.

Window placement:
Window placement is usually worked from the top down. The tops of windows are normally placed at the same heights as the top of adjacent doors generally about 81 1/2” from the floor.

A typical living room window height is 60” or about 20” – 21” from the floor to the bottom of the window, which is a reasonable height from the floor for viewing, but not too low for reaching hardware to operate the opening windows. Keep in mind the closer the glass is to the floor, the more the glass is prone to be cold, more smudges and potential damage from children and pets.
Dining rooms work well with the bottom of the windows being about 30” to 32” off the floor or a typical window height of about 48” – 50”. This is a good height for viewing from a sitting on a firm chair without someone from outside looking in under table level.
Kitchen windows over the counter should be about 40” to 42” off the floor, or approximately 38” to 40” window height. This provides good viewing from the standing position even for those who not very tall. Don’t forget most counter heights are 36” and backsplashes are 3” to 4”. Glass close to the countertop over a sink is prone to splashing on it. Shorter people prefer both their counters and windows lower.
A nice height for bedroom windows is about 40” to 46” from the floor or window height of bout 34” to 40”. This allows flexibility for furniture placement, a good height for fire escape, good viewing when standing at the window, while still providing privacy.
Bathroom and utility room windows are optional. Very often, air quality is controlled through mechanical means. If you are going to use a window in these areas, they are best at about 50” – 56” area off the floor or 24” to 30” window height to provide light and a view, while maintaining more privacy and less sight path to your laundry area from the outside.
Basement windows should be no less than 28” high and would be better if they were 32” high. This means your foundation should be out of the ground about 48” or you will have to use window wells to use a better quality casement window.

Decorative window grills:
Internal grills as decoration are available in many different sizes, colours, and designs. Technically, the research council suggests that the use of grills increase U-value and decreases R-value. This is due to a problem called thermo bridging, which results from the glass deflecting from the imploding air space as the sealed unit cools in the wintertime.

The problem is most severe on a dual pane where there is no second air space to combat the conduction.
It is also a greater problem where the grill bars run through the center part of the window where the glass deflects the most.
To have grills and maintain the highest performance, we recommend using a border grill design. With this design, your grill is kept to the far outside basically pin stripping the window keeping the center portion of the window clear for viewing and less likelihood of deflection creating any thermo bridging.
It can be a nightmare to create a pleasing design with a checkerboard grill pattern because every different size of glass cannot have the same amount of squares going across and up and down. A border grill has a distinct advantage by maintaining equal sized panes in every piece of glass regardless of width of window.

Occupant considerations:
Consider that you spend most of your time inside the home and your window design should function well for what you are doing on the inside. In our home, we have a lot of glass but we now find we have no wall space to put furniture up to or hang paintings and other accent decoration. We are not trying to discourage people from purchasing more or larger windows, but we want to ensure you think about some of these considerations. You want your home to be attractive from outward appearance, but you only pay attention to it as you drive up and park in the garage. As much as, or more important, is your inside design and aesthetic.

Requesting a quote FOR NEW CONSTRUCTION ONLY
(NOTE: FOR REPLACEMENT IN EXISTING OPENINGS NCW WILL BE RESPONSIBLE FOR MEASURING):
If you are sending in a request for a quote, it is critical to supply all the exact information. An overall rough opening can be designed in dozens of different manners with dozens of different window and glass options. At a minimum, the estimator will need a floor plan with window sizes, elevation drawings to get an idea of architectural styling, insights as to what types of windows and what options you may want. Other things you should consider is what degree of performance you are after. Different glass options and window designs will do better jobs at handling humidity, keeping warmth in the winter, keeping the heat out in the summer, give you the ability to open and close your windows easily anytime of the year, provide privacy, eliminate glare and so on.

Summary:
Do your research, then make an appointment to work on the details. By working with a window specialist you will be assured of a successful job. Window professionals with experience help make these decisions daily.