ᐅ Wooden Ceiling and Partial Insulation for Basement with Garage
Created on: 20 Jan 2021 17:54
S
Schwabe23
Hello everyone,
we are planning a passive house with a timber frame structure together with an architect. The house will have a basement, with part of the basement used as a garage. We want to minimize the footprint as much as possible because the garden is very important to us. The other two rooms in the basement are intended to be used as storage space and a small workshop, possibly also for technical equipment. The basement is only expected to be heated temporarily, if at all. The kitchen will be located above the underground garage. We have discussed various options, and the garage keeps posing challenges because, of course, opening the garage door will let a rush of cold air into the house.
The architect’s proposal is to exclude the basement from the thermal envelope and build an insulated wooden ceiling above the basement to prevent thermal bridges. The ceiling is mostly above ground level and would only need to be separated from the earth with a shaft over a distance of about 5 meters (16 feet). The garage would not be insulated at all, and the rear utility rooms would only be insulated on their exterior walls. The interior wall facing the garage would of course be insulated as well. Naturally, the concrete walls would need to be properly reinforced to withstand the earth pressure.
An alternative would be to build a conventional concrete ceiling and extend the thermal envelope around the basement, but in that case the garage would need to be insulated from the inside so that we don’t get cold floors in the kitchen.
Do you have experience with wooden ceilings in lightly insulated basements? What do you think of this approach? I am concerned that different climate zones might lead to mold development.
Many thanks in advance for your help
we are planning a passive house with a timber frame structure together with an architect. The house will have a basement, with part of the basement used as a garage. We want to minimize the footprint as much as possible because the garden is very important to us. The other two rooms in the basement are intended to be used as storage space and a small workshop, possibly also for technical equipment. The basement is only expected to be heated temporarily, if at all. The kitchen will be located above the underground garage. We have discussed various options, and the garage keeps posing challenges because, of course, opening the garage door will let a rush of cold air into the house.
The architect’s proposal is to exclude the basement from the thermal envelope and build an insulated wooden ceiling above the basement to prevent thermal bridges. The ceiling is mostly above ground level and would only need to be separated from the earth with a shaft over a distance of about 5 meters (16 feet). The garage would not be insulated at all, and the rear utility rooms would only be insulated on their exterior walls. The interior wall facing the garage would of course be insulated as well. Naturally, the concrete walls would need to be properly reinforced to withstand the earth pressure.
An alternative would be to build a conventional concrete ceiling and extend the thermal envelope around the basement, but in that case the garage would need to be insulated from the inside so that we don’t get cold floors in the kitchen.
Do you have experience with wooden ceilings in lightly insulated basements? What do you think of this approach? I am concerned that different climate zones might lead to mold development.
Many thanks in advance for your help
S
Schwabe2322 Jan 2021 21:23From a traditional perspective, certainly. However, we have also given a lot of thought to our living situation. By the way, the small bathroom has a window located above the entrance area. These are two different levels, which you can see from the exterior view. Honestly, we planned the room as a kind of multipurpose room.
- Care room if a parent requires it
- Guest room for overnight visitors (Our parents live 80 km (50 miles) away and often stay overnight)
- Spare room if finances get tight (the Ulm region is attractive for tourism)
- Currently, it would probably serve as my home office, though who knows how long that will be necessary
- When you are older and less mobile, it will surely be convenient to have everything important arranged on one level.
I hope someone can still provide input regarding the basement ceiling.
- Care room if a parent requires it
- Guest room for overnight visitors (Our parents live 80 km (50 miles) away and often stay overnight)
- Spare room if finances get tight (the Ulm region is attractive for tourism)
- Currently, it would probably serve as my home office, though who knows how long that will be necessary
- When you are older and less mobile, it will surely be convenient to have everything important arranged on one level.
I hope someone can still provide input regarding the basement ceiling.
Schimi179123 Jan 2021 07:45Schwabe23 schrieb:
... because, of course, when the gate is opened, a rush of cold air will enter the house. ...That also happens when the front door is opened, or does a passive house have a sophisticated airlock system? 🙂Do the garages not have an additional door leading to the basement?
A bathroom of only 4.4 sqm (47 sq ft) in the granny flat might be quite small for a person in need of care. What about if both parents require care? Depending on the level of care needed, is that something you really want? We went through that experience. Despite support, we decided in the final phase to move to a nearby care facility. Now acquaintances of ours are in the same situation with both parents. The overload and near nervous breakdown happened very quickly.
I personally consider a children's room smaller than 12 sqm (129 sq ft) unreasonable 🙂
I would also exclude the basement from the thermal envelope. The rush of cold air when opening the front door is nothing compared to an open garage door, and the other basement rooms are not living spaces, so separation is justified. I do not fear mold, as there are two climate zones, thermally separated, also with a vapor barrier.
S
Schwabe2323 Jan 2021 09:03Great, thank you very much! And would a wooden ceiling in the basement have no drawbacks? We are currently dealing with this issue in our rental apartment at the door. It’s warm and humid inside, but right behind it is the main entrance, which often stays open. So, it’s cold and dry there. In winter, you can see through the gap between the door and the frame because the door warps completely.
The care room would only be necessary if one parent outlives the other. Otherwise, they would prefer to stay together. Whether we can and want to follow through with this until the very end remains to be seen.
Regarding the children’s rooms, you should know that we have only one child. Based on our experiences during the lockdown, I doubt a second will be added. The separation of the two children’s rooms is only virtual and would only be implemented if needed. So, in fact, it is just a placeholder. Depending on the age of child number one, the granny flat could be used if we don’t need it yet. I grew up in 7m² (75 sq ft) and had a happy childhood without missing anything. We can also make use of the ceiling height in the rooms since the sloping roof remains open, allowing for a maximum height of 3.20m (10.5 ft).
That’s the downside of this house design. We can’t create two large rooms here because you would have to walk through the front room to get to the back one. Plan B would be to close off the gallery, although that would really hurt us since, quite literally, it is a “highlight” of the house.
The care room would only be necessary if one parent outlives the other. Otherwise, they would prefer to stay together. Whether we can and want to follow through with this until the very end remains to be seen.
Regarding the children’s rooms, you should know that we have only one child. Based on our experiences during the lockdown, I doubt a second will be added. The separation of the two children’s rooms is only virtual and would only be implemented if needed. So, in fact, it is just a placeholder. Depending on the age of child number one, the granny flat could be used if we don’t need it yet. I grew up in 7m² (75 sq ft) and had a happy childhood without missing anything. We can also make use of the ceiling height in the rooms since the sloping roof remains open, allowing for a maximum height of 3.20m (10.5 ft).
That’s the downside of this house design. We can’t create two large rooms here because you would have to walk through the front room to get to the back one. Plan B would be to close off the gallery, although that would really hurt us since, quite literally, it is a “highlight” of the house.
Schimi179123 Jan 2021 09:12Schwabe23 schrieb:
...
The open garage door and the other basement rooms are not living spaces, so there is a separation.
...That’s why I’m asking if there is no additional door between the basement and the garage(s)…Schwabe23 schrieb:
I grew up in 7m2 (75 sq ft) and had a happy childhood without missing anything.So does it HAVE to be the same for one’s own child?Schwabe23 schrieb:
The division between the two children's rooms is only virtual and would only be implemented if needed.Well, that sounds quite different... 😉Schwabe23 schrieb:
...
Based on the lockdown experience, I doubt there will be a second one added.If only Merkel and Giffey knew that... 😀The separation between the garage and the house definitely requires an insulated fire-rated door, which I assume is also airtight—your architect will likely have experience with this.
What stands out to me is the large glass area with air space; in summer, it can reach 40-50°C (104-122°F) up there, and you will be sleeping inside the thermal envelope.
This should be discussed with the architect:
- electrically operated tilt windows upstairs,
- air conditioning,
- reflective glass (neighbor’s high seat),
- sun protection.
For the granny flat or secondary unit, try to minimize load-bearing walls, use double layers of plasterboard, the blue acoustic insulation boards, and plan the locations of future doors in the stud walls in advance to make later modifications easier and less labor-intensive.
What stands out to me is the large glass area with air space; in summer, it can reach 40-50°C (104-122°F) up there, and you will be sleeping inside the thermal envelope.
This should be discussed with the architect:
- electrically operated tilt windows upstairs,
- air conditioning,
- reflective glass (neighbor’s high seat),
- sun protection.
For the granny flat or secondary unit, try to minimize load-bearing walls, use double layers of plasterboard, the blue acoustic insulation boards, and plan the locations of future doors in the stud walls in advance to make later modifications easier and less labor-intensive.
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