Background
We are about to start renovating an old house with a timber frame from the early 1900s, currently heated by direct-acting electricity. Since we plan to settle permanently in the house, electricity does not seem like a sustainable option, so we plan to install a ground source heat pump and a hydronic heating system with underfloor heating on the ground floor. The existing floor is cold and needs to be leveled as it is sloping. As I see it, there are two options..
Option 1
Tear up the existing floor and remove the existing joists. Then we lay a moisture barrier on the ground, followed by installing a new floor. Underfloor heating cassettes such as http://www.uponor.se/templates/Page.aspx?id=1940 are placed between the new beams.
How much insulation is required and how much air space is needed between the ground and the joists?
Option 2
Tear up the floor and joists and make room for a “modern” slab inside the existing foundation. With gravel, foam insulation (30cm), and a concrete slab (10cm) including underfloor heating. Since we desire the same floor height, the slab will be poured between the timber frame (separated with paper).
Here is an example of this solution http://ostragarden.blogspot.com/
It would be very interesting to have some discussion around these two options.
Primarily thinking about the total cost, moisture issues, heat efficiency, and personal experiences!
Attached is a picture we've taken in the existing foundation...
We are about to start renovating an old house with a timber frame from the early 1900s, currently heated by direct-acting electricity. Since we plan to settle permanently in the house, electricity does not seem like a sustainable option, so we plan to install a ground source heat pump and a hydronic heating system with underfloor heating on the ground floor. The existing floor is cold and needs to be leveled as it is sloping. As I see it, there are two options..
Option 1
Tear up the existing floor and remove the existing joists. Then we lay a moisture barrier on the ground, followed by installing a new floor. Underfloor heating cassettes such as http://www.uponor.se/templates/Page.aspx?id=1940 are placed between the new beams.
How much insulation is required and how much air space is needed between the ground and the joists?
Option 2
Tear up the floor and joists and make room for a “modern” slab inside the existing foundation. With gravel, foam insulation (30cm), and a concrete slab (10cm) including underfloor heating. Since we desire the same floor height, the slab will be poured between the timber frame (separated with paper).
Here is an example of this solution http://ostragarden.blogspot.com/
It would be very interesting to have some discussion around these two options.
Primarily thinking about the total cost, moisture issues, heat efficiency, and personal experiences!
Attached is a picture we've taken in the existing foundation...
I'm working on roughly the same thing, I've torn out the floor and will probably aim to level it again. I'm digging away soil and removing large stones to make room for plumbing, then it will be gravel with plastic on top. I'm also interested if anyone has any tips or similar.
I'm considering buying a house and have the same issue with the property we're looking at. Had an inspector there today, and his advice was to cast a new slab in the crawl space to eliminate future problems. Fortunately, we only need to cast 1/3 as the rest is a concrete foundation. The average cost with contractors is about 3000 SEK/m3. If anyone has more information, I would be grateful.
We just did that on our first house project, an 1800s cottage. We chose to install a new floor structure, since the timber frame in the exterior walls was intact, it felt best to continue having ventilation under the foundation. I have no idea if it makes any difference, but since the timber was remarkably sound and the house otherwise had no damage, it seemed like a bad idea not to build a similar foundation to the one that had kept the house healthy for over 100 years. Moreover, we saved the chimney that stood on a stone chest which was easier to build into than to somehow cast around, and where no moisture barrier could be laid.
Building conservationist
· 3 512 posts
I am following this thread with interest because I will eventually need to redo the floors in an old house myself.
In building conservation, it's generally advised against pouring concrete in old houses as it can lead to moisture problems. At the same time, I have the impression on this forum that most renovators are eager to pour concrete again in the foundation. The reasoning is often to avoid moisture problems! I find this very contradictory! Since pouring concrete is a relatively large and irreversible intervention, I wonder what the advantages of pouring concrete are and why it seems to be a knee-jerk reaction for most renovators that old foundations should be poured again.
In building conservation, it's generally advised against pouring concrete in old houses as it can lead to moisture problems. At the same time, I have the impression on this forum that most renovators are eager to pour concrete again in the foundation. The reasoning is often to avoid moisture problems! I find this very contradictory! Since pouring concrete is a relatively large and irreversible intervention, I wonder what the advantages of pouring concrete are and why it seems to be a knee-jerk reaction for most renovators that old foundations should be poured again.
Building conservationist
· 3 512 posts
PS to Jonaz: Underfloor heating and wooden flooring are probably not considered the ideal combination. The wood dries out and shrinks, creating large gaps.