Hello! After the construction company we hired completely blew the budget on our 30 sqm extension, we have to finish building our house ourselves. I'm now considering insulation.
We plan to go full height with a partial loft, constructing a so-called warm roof. The roof beams are 22 cm thick, and of that, about 2.5 cm will be an air gap. The rest I was thinking of filling with regular mineral wool, followed by a vapor barrier, battens, and ceiling.
What I haven't considered before is insulating crosswise as well, that is, a layer of insulation in the other direction. This breaks the thermal bridges caused by the beams and, of course, provides a bit more insulation.
However, due to space constraints, it would be good to skip the extra layer, as the loft is low enough as is, and 20 cm of insulation is quite a lot really, compared to the majority of old houses. I'm not aiming to build a passive house; the rest of the house is 200 years old and made of timber, so it probably won't work anyway. =)
It's hard to get a sense of it, but I think it doesn't matter much if the insulation is 200 or 300 mm, I can handle the heating cost, but I am worried about condensation. If it's a thermal bridge, there should be a certain risk of getting condensation on the inside of the vapor barrier, where the beam is, right?
Do I need overlapping insulation because of condensation? Is it foolish to only insulate between the beams?
This dilemma also applies to the exterior walls.
Anyone know?
We plan to go full height with a partial loft, constructing a so-called warm roof. The roof beams are 22 cm thick, and of that, about 2.5 cm will be an air gap. The rest I was thinking of filling with regular mineral wool, followed by a vapor barrier, battens, and ceiling.
What I haven't considered before is insulating crosswise as well, that is, a layer of insulation in the other direction. This breaks the thermal bridges caused by the beams and, of course, provides a bit more insulation.
However, due to space constraints, it would be good to skip the extra layer, as the loft is low enough as is, and 20 cm of insulation is quite a lot really, compared to the majority of old houses. I'm not aiming to build a passive house; the rest of the house is 200 years old and made of timber, so it probably won't work anyway. =)
It's hard to get a sense of it, but I think it doesn't matter much if the insulation is 200 or 300 mm, I can handle the heating cost, but I am worried about condensation. If it's a thermal bridge, there should be a certain risk of getting condensation on the inside of the vapor barrier, where the beam is, right?
Do I need overlapping insulation because of condensation? Is it foolish to only insulate between the beams?
This dilemma also applies to the exterior walls.
Anyone know?
Here are many different theories...
What does it say in your building permit (if you have one)? It may be appropriate to follow that.
Otherwise, you can go with insulation between the studs, a vapor barrier, 45mm space for electricity which you also insulate, and then you get 45mm more insulation.
I believe the recommendations from Boverket for sloped roofs are at least 300mm of insulation or maybe even more.
When I built out, I had to have 220mm + 10cm in the walls (with Västkustskiva 10cm to break thermal bridges) to achieve the correct insulation value...
What does it say in your building permit (if you have one)? It may be appropriate to follow that.
Otherwise, you can go with insulation between the studs, a vapor barrier, 45mm space for electricity which you also insulate, and then you get 45mm more insulation.
I believe the recommendations from Boverket for sloped roofs are at least 300mm of insulation or maybe even more.
When I built out, I had to have 220mm + 10cm in the walls (with Västkustskiva 10cm to break thermal bridges) to achieve the correct insulation value...
No building permit, so no restrictions there. Yes, sure, the Swedish National Board of Housing, Building and Planning recommends this or that, but it means nothing in practice. Without a motivation for the recommendation, it feels entirely pointless. Old houses manage fine with significantly less, and the people living there aren't suffering. That the heating cost is higher is, as mentioned, one thing, but the interesting question is whether there are any risks with building this way.niblom said:
