Member
· Västra götaland
· 335 posts
Hello
I have a question that someone here has probably encountered before and can help me with.
It's now time to insulate the garage and the question is whether something should be placed on the inside of the insulation, such as a wind barrier or plastic, or if there's something else that can be put there or if it's unnecessary?
The garage is connected to the house along 2 walls, and the walls facing the garage are already plastic-wrapped on the inside in the house, so should you really plastic-wrap again on the exterior wall of the garage?
The garage is intended to be unheated, but in the future, I believe a heat pump or something similar might be installed to keep it frost-free in the winter, though not heated to 20 degrees.
Grateful for answers
Jimmy
I have a question that someone here has probably encountered before and can help me with.
It's now time to insulate the garage and the question is whether something should be placed on the inside of the insulation, such as a wind barrier or plastic, or if there's something else that can be put there or if it's unnecessary?
The garage is connected to the house along 2 walls, and the walls facing the garage are already plastic-wrapped on the inside in the house, so should you really plastic-wrap again on the exterior wall of the garage?
The garage is intended to be unheated, but in the future, I believe a heat pump or something similar might be installed to keep it frost-free in the winter, though not heated to 20 degrees.
Grateful for answers
Jimmy
Member
· Norrbotten
· 3 390 posts
If you plan to insulate, you likely do so to keep it warm; otherwise, insulation is a bit unnecessary. If you continuously keep it heated, but not to indoor climate (+20°C), then you should probably install plastic. Naturally, you should not place plastic against what is currently the house's exterior wall. The difficulty that arises is that the plastic should ideally connect to the house's interior plastic, which is probably impossible.
Then it becomes important to ensure that there is a constant negative pressure in the garage.
Then it becomes important to ensure that there is a constant negative pressure in the garage.
As you yourself say, you should not place plastic against the walls facing the house; however, you can apply a wind barrier on those walls. That wind barrier should then be taped together with the plastic you have on the exterior walls and the roof.
The wind barrier breathes but stops the draft that could otherwise draw moisture into the construction. If you have a negative pressure in the garage, the wind barrier helps by not drawing in cold air, thus being energy-saving. Yes, marginally of course, since it's just a garage.
Another alternative is, depending on how it is constructed now, to have an air gap between the garage wall and the house wall. This air gap should then be open outward so that you essentially have two standalone structures. Then you can have plastic on those walls.
Don't forget the ventilation.
Edit:
If you are not going to heat it, it might be good to only have a wind barrier in all the walls; otherwise, you might get a refrigerator effect in the garage during summer, meaning the garage is cooler than outside. And then you might get condensation on both sides of the plastic, which is not good. In that regard, it's better with a wind barrier, as the refrigerator moisture can dry out.
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The wind barrier breathes but stops the draft that could otherwise draw moisture into the construction. If you have a negative pressure in the garage, the wind barrier helps by not drawing in cold air, thus being energy-saving. Yes, marginally of course, since it's just a garage.
Another alternative is, depending on how it is constructed now, to have an air gap between the garage wall and the house wall. This air gap should then be open outward so that you essentially have two standalone structures. Then you can have plastic on those walls.
Don't forget the ventilation.
Edit:
If you are not going to heat it, it might be good to only have a wind barrier in all the walls; otherwise, you might get a refrigerator effect in the garage during summer, meaning the garage is cooler than outside. And then you might get condensation on both sides of the plastic, which is not good. In that regard, it's better with a wind barrier, as the refrigerator moisture can dry out.
//
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Member
· Västra götaland
· 335 posts
Well, the insulation is meant to keep the garage frost-free rather than heated to +20 degrees. But what is it that is used in old houses? Some type of tar paper on the inside or is it wind barrier?? Doesn't it have a preventing function for moisture migration? J
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For everything in the world, do not put plastic in the ceiling; choose a windproof sheet as someone wrote. I made the mistake of putting plastic in my garage ceiling because I planned to heat it to +10 degrees, but I never got around to installing the heat pump. The first spring sun made sure there was a lot of moisture on the inside, but only up at the ridge and 1 meter down on each side. I have now torn down all the plastic in the ceiling and put windproof sheet instead. I'm leaving the plastic in the walls as is.
/CC
/CC
Member
· Västra götaland
· 335 posts
Yes, this is really not easy. There are many different opinions on this. I will probably invest in windproof fabric (which I interpret as wind barrier) in the walls and roof. I will probably be in the same situation as you, Chris, and never get that heat pump installed, so the garage will mostly follow the outside temperature. Additionally, there is a big risk that it is warmer outside than inside the garage since the long side faces south, also without windows. This means that the inside is delayed in warming when the sun shines.
Sure, it can be a problem with cold premises. I don't have any plastic in mine, but I do have windproofing and properly insulated = 195mm in the walls among other things. I also noticed at some point that everything was soaking wet inside, and this was due to too little ventilation. Finally, I have to say, the air-to-air heat pump is installed.