Tips for Insulating Glass on Doors

See how to insulate single-pane glass on doors to improve your home's heat and energy efficiency during the winter.

I’m all over efficiency and insulation these days (and to give an enthusiastic update, my recent door sweep installation has eliminated all signs of a drafty attic door!). I work from home, and because I’m having to heat the home to a bearable temperature all day, every degree that I can preserve is especially worthwhile. I realize many people in the country are already digging their way out of the first snowstorms of the season, but we just had our first frost last week and it was a friendly little reminder for us to get our hoses inside, our lawn furniture stored away, and our sunroom weatherproofed.

There’s not much that you can do to prevent a 3-season sunroom from reaching frigid temperatures when the wind’s a-blowin’; both the windows and floor in mine are essentially R-0 on the R-value scale, but that doesn’t mean that I can’t do my best to seal that cold room off from the rest of the warm house.

Last year, I made a heavy felt roam shade that provided so much insulation it’s uncanny. I also added foam weatherstripping (get a full tutorial on how to do that that right here) which gave a nice, secure seal around the edges of my door’s frame. The combo improved our insulation situation markedly, although I’m not an R-value guru so I can’t guesstimate how much it was improved in a super technical sense, you’ll just have to take my word on it. I just like to be warm and efficient and those two things seemed to help a lot.

This year I’m taking it a step further.

Adding a window insulation kit to the paned glass door may or may prove to not make a huge difference in my home’s ability to conserve heat, but I’m optimistic.

To achieve the greatest efficiency, I’ve read that the insulation should be 1″ from the glazing on the glass, and by my measurements, the glass panes do sit in the middle of our heavy 2″ wooden door. The glass itself is a single pane, so as you can imagine, it isn’t much of a barrier to cold air. Even if after this project is said and done, if it’s not sealed to maximum efficiency, my efforts will create a storm window-like effect over the existing glass, and that’s better than nothing as it relates to helping to fend off weather and limit the cold air infiltration.

Note: Consider your own situation when installing window and door insulation. A more commonly recommended approach is to seal the film in one of these kits to the window/door frame rather than to the door itself. I’m affixing it to the door around the windows only because I will still need access to my sunroom during the winter months, and sealing off the door entirely would mean I couldn’t access that room until springtime.

To start, I wiped down the outer-facing side of my sunroom door. I decided to install this film on the outside of the door to help prevent airflow at the first point of contact. I used a rag that had been soaked in a little TSP-PF to help clean the surface as best as possible so that there was no residue that would affect how well the insulation adhered.

The kit I bought came with double sided tape, which I used to line the perimeter of the glass paned area.

I also added a few pieces of the double-sided tape between the panes just to help hold the plastic in place. No harm in extra support, right?

Hanging the plastic onto the double-sided tape was no big deal – quite manageable a task for anyone, I can imagine. Once I had it lined up, I used a razor blade to gently trim away the excess. The product’s instructions advised to get it as smooth and taut as possible by hand first, but using a hair dryer on a hot setting really tightened everything up.

Other reviews of the product prepared me for my window looking, uh, cellophane-y, which it does from the outside, but the impact is surprisingly minimal and the effect is contained to the places where the plastic overlaps the wood.

I mean, look at how transparent my view is from the inside? Paired with curtains that also help to insulate the doorway, I hope this helps to keep our living room warm as the temperatures continue to drop!

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