We have a furnished room in the attic with a small door leading to the cold attic. It is a thin door and not insulated, and I assume that's why the room is only 15-16 degrees now in the winter? And it probably isn't good in the long run as warm air also escapes into the attic? What is best to insulate the door with and what is simplest.
It is true that it's less ideal to have warm air leakage into the cold attic since that air contains about 1 gram more water vapor than cold air per cubic meter. The temperature drop causes that moisture to 'precipitate' and create a breeding ground for black mold on the underside of the roof panel, etc.
Then it depends on whether the door swings inward or outward to the cold attic.
If it is inward, you can build onto the door leaf with battens/studs and insulate with foam boards of suitable thickness which you glue in place with adhesive for foam. (You will likely have a door as thick as the wall.)
Then cover the insulation with a 3.2 hard wood fiber board, also glued. (You have to be careful that the door can open, particularly on the lock side (where the door handle is).)
On the hinge side, you can seal with an OPDM rubber strip against the frame. On the lock side, the top side, and the threshold, you will have to build up with a thin wooden strip/batten on the outside of the wall and seal with sufficiently thick foam rubber between the door leaf and the strip/batten, attached to the frame.
If it is outward, it is advisable to arrange with a thick curtain on the inside so that there is an air gap between the door and the curtain.
____________________
Byggaren
Then it depends on whether the door swings inward or outward to the cold attic.
If it is inward, you can build onto the door leaf with battens/studs and insulate with foam boards of suitable thickness which you glue in place with adhesive for foam. (You will likely have a door as thick as the wall.)
Then cover the insulation with a 3.2 hard wood fiber board, also glued. (You have to be careful that the door can open, particularly on the lock side (where the door handle is).)
On the hinge side, you can seal with an OPDM rubber strip against the frame. On the lock side, the top side, and the threshold, you will have to build up with a thin wooden strip/batten on the outside of the wall and seal with sufficiently thick foam rubber between the door leaf and the strip/batten, attached to the frame.
If it is outward, it is advisable to arrange with a thick curtain on the inside so that there is an air gap between the door and the curtain.
____________________
Byggaren
