Add Flexibility to Plastic Window Kits

One of the things that has discouraged me from using these seasonal window insulating kits in the past is the fact that once they’re installed you can’t open the windows for the rest of the season.

If you burn the fish and need to air out the room it’s decision time — do you sacrifice the window kit or take the battery out of the smoke detector?

What if you could just unseal the window for a few minutes and then seal it back up?

Plastic window film can be removed Having just added some insulation to our old stone basement walls I needed to install temporary insulating film on the windows but didn’t want to deal with the use-it-once and throw it out issue associated with the double sided tape used to fasten it — not to mention cleaning off the tape residue when you remove it in the spring. I want to be able to remove the film in the spring and easily re-install it each fall. My brother-in-law suggested an idea that sounded like the solution for my situation — using the rubber spline that’s designed for window screens.

After measuring the window boxes, I ripped narrow strips of 3/4″ thick stock and then lowered the blade to cut a shallow groove (3/16 to 1/4″ deep) down the centre of the strip which is the width of the saw kerf (1/8″). I cut frames with mitred corners to fit the existing window boxes. The mitred corners make a continuous channel around the whole window.

After attaching the 3/4″ frames to the boxes with small finish nails, I eased the inside corners with narrow chisel to make sure the spline would make the 90 degree turns (which it did even without the eased corner). A small bead of caulk on the back of the strip helped make it airtight.

All that was left was to cut the film and install it. I had picked up a kit with a large-size piece of film so I could cut it for the most efficient use and some ribbed spline just slightly larger than the 1/8″ wide groove (.140″ or 9/64″).


How to install the window kit:

1. Cut the film about 4″ -6″ larger than the opening to give you something to hold on to.

2. Position the film with equal overlap on all edges (you may need another pair of hands on larger windows).

3. Plan on where you want the joint in the spline to be and roughly measure the distance from there to the top centre by holding the spline against the groove and finding the point on the spline that would be top centre. The spline will stretch a bit as it’s pushed into the groove so accuracy isn’t important.

4. Start at the top centre and push the spline into the groove with the film behind it. Keep a bit of tension on the film as you run your thumb along the spline which should easily slip into the groove, securing the film. If the film goes crooked or gets too wrinkled just pull out a few inches of the spline re-adjust the film and continue on.

5. Leave a little tab of spline at the joint to grab when you want to remove it.

6. I didn’t bother heating it up to get the wrinkles out since appearance doesn’t matter and I intend to re-use the film several times. I’m pretty sure stretching it with heat would eliminate any possibility of re-using the film.

Tip: These windows are in an unfinished basement so I wasn’t concerned about appearance, but this method could be easily adapted to finished windows within your living space by painting the grooved strips (or cutting a groove in a suitable moulding from the local building supply store). If your existing window trim has mitred corners you can carefully remove it, cut the 1/8″ groove in it, and reinstall it. The black spline will give the appearance of a custom trim detail.

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