Editorial & Photography By: Dr. Christopher Cooper
For decades now window manufacturers have sponsored studies to prove that traditional wooden window systems aren’t energy efficient. Of course today the window manufactures are hard at work replacing windows, no, not antique wooden windows, rather the junk they installed as little as a decade earlier.
Very simply, a traditional wooden window coupled with a traditional wooden storm is equal to, or in most cases more energy efficient than a thermal replacement window. The traditional window system in an older home is the most important character defining element of all.
Just do the math!
Note how distracting raw aluminum storms can be.
If there is as much as 20 percent† of the heat loss through single glazed windows and that percentage can be reduced in half by simple restoration techniques applied to the principal sash and by installing another layer of glazing in the guise of a wooden storm window (which can be built by the average home woodworker for less than $150.00, based on a storm window 3’0” x 5′-0” providing a U-value of 0.50‡), then the frugal homeowner should realize that the $150.00 spent building a storm window can very easily be paid off in energy savings in approximately five years.
On the other hand if the ill-advised replace their original system with a new thermal unit which will run you in the ballpark of $1,300.00 (based on the same 3′-0” x 5′-0” opening installed with a U-value 0.58), the return on the investment would not be realized for approximately 250 years! And I would hate to see what a plastic window would look like even after 25 years, notwithstanding how ugly they are when they are new!
The same aluminum storm painted out to match the existing colour scheme of the principal sash windows.
A huge trend in the 1970’s was to install aluminum storm windows over older wooden sash windows. I do and I don’t have a problem with this. Raw aluminum is unattractive and some measure should be taken to paint the aluminum storm to better blend with the sash. Many problems arise with these types of storms as they can hold copious amounts of water on the interior side, and many people caulk the bottom where it comes in contact with the sill or sub sill. This area where the storm comes in contact with the sill or sub sill should not be caulked or sealed. Moisture needs to find its way under and out of the interior at this location, even on a wooden storm window.
The newer plastic storm windows, in my opinion, are completely useless because they will become brittle in as little as five years. Wooden storm windows, on the other hand, have been in service in many cases as long as 130 plus years. Our Blenheim Farm location still has original storm windows in place on the summer kitchen which was built in 1877. Yes these storms have many condition problems, nonetheless, what would a plastic window look like after 132 years?
I have been asked the question, what are the holes for in the bottom of the storm window? These are clever little vents with a wooden flap to close them off. Whenever you have a steamed-up window or just want some fresh air, swing these flaps open (on the interior side), and you will be amazed at how much fresh air you can get out of three or four little holes (see Image 1).
Above Image 4: Segmented windows can be properly hung on a single hanger. Note the long eye hooks used to set the storm in an awning position, a very simple and cost effective approach. Full circle head and Gothic head windows can be hinged at their sides and can be operated with casement window hardware.
One of the largest drawbacks with respects to heavy wooden storm windows is that they need to be removed every summer and stored away. During the hot and humid summer months, damaging condensation can attack the principal window and cause rot issues. As technology advanced in wooden storm windows, so did the hardware. I have always recommended that storms are set on hangers (see Image 2) with a set of articulating window adjusters (see Image 3). These window adjusters set the window in an awning position (see Image 4) and best of all they lock the storm in place adding a secondary level of security for your home, with no heavy storms to stow away in the summer.
As for weather stripping I recommend EPDM weather stripping (available at most hardware and big box stores, see above). Place the weather stripping on three sides of the storm window, the left, the right and the top of the storm where it sits flush either on the exterior architraves (see Image 5) or in the rebate in later windows of the nineteenth century and early twentieth century (see Image 6). Never seal the lower portion! Once the window adjusters are locked into place the EPDM will compress and keep a positive draught-proof seal.
There are a variety of storm windows available with lower glass panels that can be changed out in the summer time for screens. These are usually fussy and, in my opinion, overpriced options, which can be better served with window adjusters and an accordion screen fit snugly under the lower sash of the principal window. Never use interior storm windows. Here is a direct quote from the National Parks Service preservation briefs’: “Moisture which becomes trapped between the layers of glazing can condense on the colder, outer prime window, potentially leading to deterioration. The correct approach to using interior storms is to create a seal on the interior storm while allowing some ventilation around the prime window. In actual practice, the creation of such a durable, airtight seal is impossible.” Never use shrink plastic, as this causes the same problem and will discolour and tear the paint on the architraves.
An example of quality craftsmanship, note the intricacy of these Gothic-head storms
Wooden storms always create the right look for a heritage property, even when they are showing their age.
The old wooden windows in your home have given you and your predecessors great service. Good stewardship and good energy savings can be had in restoration and by providing a good quality wooden storm! Take care of your wood windows and storms and they will give you an indefinite number of years of service!
† The principal culprit affecting energy consumption is air infiltration; it can account for as much as 50 percent of the total heat loss of a building. Sadly, a couple of hundred dollars in caulking can reverse this number, without removing windows and destroying character defining plaster walls and creating a health issue with other chemicals and foams being pumped into walls that can no longer breathe!
‡ The U-value (or U-factor), more correctly called the overall heat transfer coefficient, measures the rate of heat transfer through a building element over a given area, under standardized conditions. The smaller the U-value the better it is, which is the inverse of an R-Factor.