Drafty Wood Windows, in Need of Repair? 9 Simple Tips – to Save You Money this Winter!

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Editorial and Photography By: Dr. Christopher Cooper

I have found most people, including ourselves at our three Vintage Home Charm project houses, are in a flux of partially restored windows or windows that have been restored, however need a little extra work to make them a little less drafty for the winter months.

There are many options on the market to stop draft, notwithstanding this, most modern contrivances are damaging to a wood window. The plastic, two-sided tape, and a hair dryer over the window trick, does nothing but cause condensation on the principal window, which allows the principal windows to mold and rot. Moreover, the two-sided tape will destroy the paint on the window trim. Another product is a caulking that is supposed to be easily peeled-off in the spring, along with your paint too. And in most cases, you will have to scrape off the excess, damaging the underlying wood.

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This article will take a low-tech approach to stopping drafts, and in turn save on energy consumption without any newfangled, new-and-improved, buy-it-now products. The first approach is to see if there is draft around the windows where the sash slides in the frame and comes in contact with the stool (on the lower edge of the sash). By using an incense stick, one can detect air infiltration by seeing a break in the smoke stream from the incense. Smoke rises without a draft, however when caught in a draft, the smoke will break in a horizontal stream (see Image 1). By slowly running the incense stick around the window, areas that need attention will become very apparent.

An operating window should never be caulked rather only the window trim where it comes in to contact with the wall surface! Most air infiltration is found where the upper sash rides against the parting bead (see Image 2, only in double-hung windows) and where the lower sash rides up along the interior stop (see Image 3).

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Another area for air infiltration is at the meeting rails (see Image 4) and where the lower sash rests behind the stool (see Image 5) and at the weight pulley (see Image 6).

First, let’s take a look at the meeting rails. Most people confuse the device shown in Image 7 as a window lock, to lock your windows. These devices have been around for quite some time (mid 19th century) and in the days when you didn’t lock your front door, you certainly were not going to lock your windows! These sash locks are actually devices to lock your meeting rails together to stop draft and should be installed on all operating windows.

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There should be one sash lock for windows of 24″ and less, and two locks evenly spaced between the lights of larger windows (see Image 8).

The areas located at Images 3 and 5 are the most notorious air infiltration points. I take care of these areas using a modern product. However, it will not damage the window in any way and can be installed in minutes! Foam backer rods (available at your local hardware store) can easily be pushed into the gap at the interior stop and at the stool, effectively stopping draft in its tracks. The backer rod is pushed into place using a wooden shim I have fashioned with soft rounded edges that does not damage the surrounding wooden surfaces or tear the backer rod (see Image 9).

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I am using a 3/8″ diameter backer rod, starting on the left side of the stop at the meeting rail and running the rod down and across the stool and up to the right side meeting rail (see Images 10, 11 & 12). The results are amazing. This will completely stop the air infiltration, and if the space is bigger, the backer rods are available in many sizes starting at a 1/4″ diameter.

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This same method can be done to the upper sash in double-hung windows and placed between the upper sash’s stile and the parting bead (see Image 2). Another low-tech product available for double-hung windows (again available at your local hardware store) is crack seal (see Image 13). This product has been around for a very long time and is somewhat like the consistency of plasticine. You simply roll it out and push it in place. The product does not tear the paint and is easily removed in the spring (see Image 14). I only use this product when the gap between the parting bead and the upper sash stile is too small to push in a backer rod.

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The final air infiltration culprits are the sash pulleys. This is easily remedied with a small 4” length of a backer rod, pushed into the top of the pulley and the other end pushed into the bottom of the pulley (see Image 15). The terrific thing about backer rod is that it can be reused for years. I will put the used backer rod in a large zip-top bag and use a permanent marker to mark which room and which window it came from, then store it away until next winter (see Image 16). The crack seal can also be saved and reused!

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A good fitting wood storm window is always important to achieve a better and in some cases, higher energy efficiency over any vinyl or wood replacement window on the market today, coupled with the tips noted in this article. Another important task to be performed on your original wood sash windows and storms is to properly re-putty the glazing (see Image 17), however, we will leave that to a subsequent article.

Cracked Glass

Many of us, during the restoration of our houses, have had to deal with cracked window glass from time to time. Cracked glass can cause all sorts of discomforts when a cold breeze is finding its way through the gap during inclement weather.

I hate to say it, but we as a society tend to only replace glass when it is completely broken-out; replacement of one cracked pane is usually low on our to-do-list. A testament to this is all the cracked glass in many of our project houses.

One of the biggest concerns for me is the large cylinder glass sheets in the 1877 replacement windows in the front facade of one of our project houses. They have large horizontal cracks from one side of the sash stile to the other; they have become very unstable and await final restoration before the glass is replaced. This type of crack could be potentially disastrous with our young daughters having the run of the place.

I have found that the best possible solution to stabilize cracked glass and to stop draft is to caulk both sides of the crack with a very high quality clear marine silicone caulk.

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The Temporary Repair Process:

My apprentice, Janet, demonstrates placing masking tape on both sides of the window crack on the interior side of the window before using the silicone (see image 18). Approximately a sixteenth of an inch on either side of the crack is needed. For wavy or arched cracks, use a 2-inch-wide roll of masking tape and use a razor to trim away an eighth of an inch swath where the crack is; this will allow a smoother appearance. This step with the masking tape can be skipped if appearance is not a concern. Janet then simply runs a bead of silicone over the crack between the masking tape (see image 19).

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Then, with a moistened finger, Janet smooths out the silicone (see image 20). After the silicone is smoothed out, the masking tape is removed carefully so as not to ruin the uncured silicone (see image 21). Allow the interior repair to cure overnight and follow the same process as above on the exterior side of the glass.

The final temporary repair is relatively attractive and has stabilized the glass and stopped the draft. This is only a temporary fix and the cracked pane will eventually have to be replaced. However, it has made the pane safe for cleaning and for touching with little hands that have the run of the place!


2 Comments Add yours

  1. Angela says:

    Great article. Thank you.

    1. edificemedia says:

      Thank you Angela 🙂

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