How to build energy efficient double insulating storm window inserts with super clear and strong 3 mil polyester film, to reduce heating costs, prevent condensation, stop drafts, and winterize your windows and house.
Save money this winter on your heating bill. Very cost effective and lasting 30 years or more, these interior storm windows are much more durable and twice as warm as single shrink film window insulation kits that only last 1 or 2 years.
You can also tape clear plastic directly over nonopening picture windows and some opening windows. Adding a double insert on top of that, you're adding 3 layers of glazing to single or double pane glass, creating 34 air spaces. It's the air spaces, not the glazing that create insulation.
In the video I said each airspace adds R2, but some sources say each space adds about R1.2.
Even so, R3 double glass plus 3 air spaces x R1.2 each = R 6.6, still a huge difference.
Adding interior storm windows will also reduce air infiltration and stop condensation on inside of windows in winter. Plastic is warmer than glass to the touch, and moisture does not condense on warm surfaces.
My first inserts lasted 35 years, kept our house warm, eliminated condensation, and drastically cut our heating costs.
Especially effective if you have older drafty single pane windows, or live in a cold climate, but it's surprising how much difference they make even added to modern double pane windows.
Note that to be effective in keeping heat out in the summer, you may need external shading as well like an awning or solar screen, to keep the sun from shining in through the window.
If you want to heat shrink your plastic for a totally smooth storm window, I'd suggest 12 mil clear polyester. 3 mil may be slightly wavy but hardly noticeable, and is too thick to shrink easily.
0:00 Stop Drafts & Window Condensation
1:00 Best Way to Insulate Windows
1:49 Plastic Window Insulation
2:16 Winterize Windows & House
3:02 Best Window Insulation Film
3:46 Building Storm Window Insert
5:54 How to Build Wood Frames
7:11 Handle for Window Insert
7:37 Weatherstrip & Tape
8:33 How to Stretch Plastic
10:57 Clean & Insulate Fixed Windows
11:29 DIY Storm Window Inserts
12:17 Save Money on Heating
Materials: Here is the best deal I've found on clear polyester film, in 20" or 40" widths, 12' to 100' lengths, and I'd suggest 2 or 3 mil thickness:
https://amzn.to/3rveX3R
I use this Frost King open cell foam weatherstrip, 1/4" thick, 3/4" wide:
https://amzn.to/46m6OOg
This thicker Frost King open cell foam tape is 1/2" thick, 3/4" wide, and lower cost:
https://amzn.to/3QJ4vi2
This 3M window film mounting tape has great reviews except for a recent bad batch:
https://amzn.to/418IQ7t
The Frost King double face mounting tape is lower priced:
https://amzn.to/3GoGQ1l
Clear gorilla tape is strong and works well for a handle:
https://amzn.to/3Fr9Pkw
If you don't have a countersink, here's one: https://amzn.to/3Q8IDfI
I use Brillianize for cleaning and polishing plastic films:
https://amzn.to/3RHfOsL
Novus plastic cleaner is also great for cleaning plastic film without scratching:
https://amzn.to/3Npwe6d

As an Amazon associate, I earn a small commission on purchases you make after following these links, which is one way you can support me if you appreciate the video.
I tried some generic weatherstrip and it was not as good. You should be able to find weatherstrip and 1x2 lumber at a hardware store, lumber yard or home center.

If you need 48" wide film, ePlastics has it in 25' to 100' rolls at
https://www.eplastics.com/films/polye...
I always use is this 1/2" wide, clear double sided tape from ePlastics with peel off backing:
https://www.eplastics.com/accessories...

You'll also need screws or nails, new sharp utility knife blades, a tape measure, square, saw, drill & bits, some wax is helpful, and optional clear varnish or primer and paint.
Feel free to ask questions below or comment, and let me know if this is helpful, and if you build your own, let me know how it turns out. Thanks!