ᐅ Adding Additional Insulation to a Wooden Basement Door from the Inside

Hello!
I have and need:

• An older exterior door insulated with 18cm (7 inches) mineral wool and triple glazing all around – only the old cellar door (wood with single-glazed safety glass window) was beyond the budget. Until a new, modern door arrives, I would like to add insulation from the inside. I have on hand
• a lot of 20mm (0.8 inches) thick XPS and some of this very thick aluminum-laminated PIR:

Quick and simple insulation

• Materials:
• Dow Floormate 200 (XPS) boards
• Double-sided tape (removable)
• Vapor-permeable membrane or nonwoven fabric (optional, to prevent condensation)
• Utility knife and ruler
• Self-adhesive weatherstripping (for the edges)
• Procedure:
• Cutting:
Cut the XPS boards to the dimensions of the door. If you want to cover the glass, cut a separate piece for the glass area.
• Intermediate layer (optional):
To prevent condensation, adhere a vapor-permeable membrane or a thin anti-condensation fleece to the back of the XPS panels (the side facing the door).
• Installation:
Attach the boards to the inside of the door using the double-sided tape. Make sure they fit tightly but leave small gaps for air circulation at the top and bottom (about 2mm (0.08 inches) each).
• Improving door seals:
Apply self-adhesive weatherstripping around the edges of the door to prevent drafts.

Do you have better or faster ideas? I actually plan to remove it again in summer. Hopefully, we will have a new door around 2027 or so.

What do you think?

1. Search for a basement door in the book
2. Glue PUR foam to the outside of the glass (hope the door will still open properly)
2b. Hang a heavy curtain inside in front of the door
3. Hope to find a new door by 2027 (although I think you should be able to find a side entrance door for a relatively low cost – after all, it’s “just” the basement door)

Hello!
Quick question: By 1., do you mean a "watchlist," like setting up an eBay alert to snag a bargain after some time? Or are you referring to some kind of book?!

THAT would certainly be a good idea! The dimensions are probably so specific that spending months searching in the region should be worthwhile. Good idea, thanks!

And the PUR foam from the outside and not from the inside? From the outside, I would have to protect it against water with tape or something similar. The wood definitely feels very cold from the inside as well. The curtain blocks convective cold without putting the wood at risk of mold... understood. Maybe I could also place a PUR-coated particle board in the reveal, which would have about a 10cm (4 inches) gap to the door and that I would just pull out the three times I go to the garden during winter. As long as it doesn’t have to be airtight but only about 95% fitting, this would be easier and faster with the existing material than installing a curtain track and buying the thermal curtain. What do you think?

Bad_Bremen schrieb:

What do you think?

An affordable and pragmatic brute-force solution. This will work.