ᐅ Insulation of the ground floor slab / underfloor heating if applicable
Created on: 18 Feb 2021 13:42
W
Winniefred
Winniefred18 Feb 2021 13:42Hello!
We plan to insulate the ground floor floor this autumn. We have a house from 1921 with a vaulted cellar that is not insulated. Insulating the cellar ceiling is not an option, so we want to insulate the floor. We have been living here for 3.5 years and in winter it feels too cold underfoot, plus it’s also a building regulation requirement. We will start with the living room this year and then do the rest gradually. The cellar remains at a constant 14°C (57°F), but we want to address this to save even more on heating costs (the rest of the house is well insulated and our heating energy consumption is low).
We want to insulate as effectively as possible since we are putting in the effort anyway. The current structure is: laminate flooring, old linoleum, probably OSB underneath, floorboards, wooden beams in slag. All of that will be completely removed. I like the Fermacell floor system—it seems lightweight and suitable for DIY. The rough ceiling would need to be primed, then a bonded screed applied, followed by a rigid insulation board and then the dry screed panels. After that, I imagine a nice cork parquet or something similar.
Has anyone had experience with this setup? Or with bonded screeds in general? Are there other ideas for floor insulation that can be done as a DIY project?
We currently only have a gas heating system. Underfloor heating in the living room would be nice but is not essential. The existing radiator heats the living room perfectly well at the moment.
Looking forward to your input!
We plan to insulate the ground floor floor this autumn. We have a house from 1921 with a vaulted cellar that is not insulated. Insulating the cellar ceiling is not an option, so we want to insulate the floor. We have been living here for 3.5 years and in winter it feels too cold underfoot, plus it’s also a building regulation requirement. We will start with the living room this year and then do the rest gradually. The cellar remains at a constant 14°C (57°F), but we want to address this to save even more on heating costs (the rest of the house is well insulated and our heating energy consumption is low).
We want to insulate as effectively as possible since we are putting in the effort anyway. The current structure is: laminate flooring, old linoleum, probably OSB underneath, floorboards, wooden beams in slag. All of that will be completely removed. I like the Fermacell floor system—it seems lightweight and suitable for DIY. The rough ceiling would need to be primed, then a bonded screed applied, followed by a rigid insulation board and then the dry screed panels. After that, I imagine a nice cork parquet or something similar.
Has anyone had experience with this setup? Or with bonded screeds in general? Are there other ideas for floor insulation that can be done as a DIY project?
We currently only have a gas heating system. Underfloor heating in the living room would be nice but is not essential. The existing radiator heats the living room perfectly well at the moment.
Looking forward to your input!
N
nordanney18 Feb 2021 14:12Winniefred schrieb:
Insulating the basement ceiling is not an option. Why?
Winniefred schrieb:
Besides, it is required by regulations. No, it is not.
Winniefred schrieb:
The current structure is: laminate flooring, old linoleum, probably OSB underneath, wooden floorboards, wooden beams in slag. First, clarify the exact construction layers. Concrete ceiling with the assumed layers on top?
It also depends on the ceiling height you can achieve.
Winniefred schrieb:
Also, we currently only have a gas heating system. Underfloor heating in the living room would be nice, but it’s not a must. The existing radiator heats the living room completely sufficiently at the moment. Underfloor heating can’t provide more heat than a radiator. Planning underfloor heating for just one room doesn’t make sense. The design effort, hydraulics with mixing valves, and cost-benefit ratio are all unfavorable.
Winniefred18 Feb 2021 14:25Because the basement ceiling would become too low and we would have to insulate all the electrical wiring and other pipes there, which would only be a patchwork solution and a real hassle. Whether it is actually required by law or not doesn’t matter, because we are insulating it for ourselves, not for the authorities. Also, at least the beams in the kitchen are damaged (sagging), and we plan to lay tiles there later, as well as in the hallway.
What should I clarify regarding the floor structure? Everything will be removed anyway. Opening it up beforehand is not an option as the house is occupied and we want to keep the construction period as short as possible. There is definitely no concrete anywhere. From bottom to top, there is a vaulted cellar (barrel vault), cinder, wooden beams, original simple floorboards, OSB, linoleum, and laminate. The OSB to linoleum layers were installed by the previous owner. Whether we rebuild with a new height of 17 or 20 centimeters (7 or 8 inches) does not matter much with a bonded fill as I have in mind. Since we have installed quite expensive interior doors on the ground floor, the floor height will be adjusted to match those.
The underfloor heating would then, of course, cover the entire ground floor, but we will do it room by room. And as mentioned, it is not mandatory and we would only implement it if it is relatively easy to do.
At this point, the focus is on the new floor construction.
What should I clarify regarding the floor structure? Everything will be removed anyway. Opening it up beforehand is not an option as the house is occupied and we want to keep the construction period as short as possible. There is definitely no concrete anywhere. From bottom to top, there is a vaulted cellar (barrel vault), cinder, wooden beams, original simple floorboards, OSB, linoleum, and laminate. The OSB to linoleum layers were installed by the previous owner. Whether we rebuild with a new height of 17 or 20 centimeters (7 or 8 inches) does not matter much with a bonded fill as I have in mind. Since we have installed quite expensive interior doors on the ground floor, the floor height will be adjusted to match those.
The underfloor heating would then, of course, cover the entire ground floor, but we will do it room by room. And as mentioned, it is not mandatory and we would only implement it if it is relatively easy to do.
At this point, the focus is on the new floor construction.
N
nordanney18 Feb 2021 14:38Winniefred schrieb:
Whether it is actually mandatory or not does not matter, because we are insulating for ourselves, not for the authorities. Then you wouldn’t have needed to write it and now reply annoyed ;-)
Winniefred schrieb:
What do I need to clarify about the construction? If you know the construction and the possible height, then everything is fine. Just please don’t get upset if in the end you are 3cm (1 inch) short for the underfloor heating because you estimated roughly.
Winniefred schrieb:
The underfloor heating would of course be for the entire ground floor, If it’s of course, then please say so instead of “if possible, we would like underfloor heating in the living room.”
It’s at least not straightforward. Whether it makes sense depends, for example, on the possible insulation below the underfloor heating. But for that, you also need to know the available space or overall build-up height.
Winniefred18 Feb 2021 14:48No offense intended, sorry!
I have a rough idea of the possible height because we can see how much space there is up to the ground floor level at the basement staircase entrance. So, up to the original floorboards, which you can see from the side there. However, since it’s a vault, I don’t expect that it was installed at the same height everywhere back in 1921—thickness and height will surely vary somewhat here and there—but we won’t really know until everything is fully removed.
With a dry construction floor build-up, incorporating underfloor heating should be possible height-wise. However, I would definitely discuss this in advance with the plumbing company, as they are very competent. For us, this is really just a minor consideration; we can easily live without underfloor heating and would see it more as a luxury addition.
It’s an old building undergoing renovation. Usually, you only see what you’re dealing with once everything is stripped back. We’re used to that. Often, you have to revise plans or buy additional materials, but that’s just how it is. So I’m not concerned about detailed planning yet—that can only be estimated once the room is open up to the raw ceiling. What I’m more interested in, fundamentally, is bonded screed, practical experience, and so on. 🙂
I have a rough idea of the possible height because we can see how much space there is up to the ground floor level at the basement staircase entrance. So, up to the original floorboards, which you can see from the side there. However, since it’s a vault, I don’t expect that it was installed at the same height everywhere back in 1921—thickness and height will surely vary somewhat here and there—but we won’t really know until everything is fully removed.
With a dry construction floor build-up, incorporating underfloor heating should be possible height-wise. However, I would definitely discuss this in advance with the plumbing company, as they are very competent. For us, this is really just a minor consideration; we can easily live without underfloor heating and would see it more as a luxury addition.
It’s an old building undergoing renovation. Usually, you only see what you’re dealing with once everything is stripped back. We’re used to that. Often, you have to revise plans or buy additional materials, but that’s just how it is. So I’m not concerned about detailed planning yet—that can only be estimated once the room is open up to the raw ceiling. What I’m more interested in, fundamentally, is bonded screed, practical experience, and so on. 🙂
P
pagoni202018 Feb 2021 15:03Basically, it will be a "standard" dry construction, for which there are many options. Underfloor heating is definitely feasible in terms of the assumed height, but whether you actually want it is another question. For example, we use wooden plank flooring without underfloor heating in our new build.
I think you should first make the fundamental decision about underfloor heating, as well as at least have an idea of the type of final floor covering you want.
Depending on your choice, you can then decide on a joist layer with any kind of insulation in between, followed by OSB boards and the final covering, among other options. There are also good underfloor heating solutions suited for this type of build, especially for DIY installation.
What insulation you choose will ultimately depend more on the insulation standard you want, the material preferences, and the cost. You can calculate and compare these factors as much as you like. Another important factor, at least in my case, is what you prefer to work with — for me, for example, loose-fill insulation is less appealing.
I found the SteicoFloor system quite interesting; there are different suppliers for that. Bauder also offers options for suspended floors with OSB on top, which I could also imagine using.
If your floor feels too cold so far and it is an older house anyway, from an aesthetic point of view, I could also imagine solid wood planks. As mentioned, there are underfloor heating solutions for those as well, which have already been discussed here.
I think you should first make the fundamental decision about underfloor heating, as well as at least have an idea of the type of final floor covering you want.
Depending on your choice, you can then decide on a joist layer with any kind of insulation in between, followed by OSB boards and the final covering, among other options. There are also good underfloor heating solutions suited for this type of build, especially for DIY installation.
What insulation you choose will ultimately depend more on the insulation standard you want, the material preferences, and the cost. You can calculate and compare these factors as much as you like. Another important factor, at least in my case, is what you prefer to work with — for me, for example, loose-fill insulation is less appealing.
I found the SteicoFloor system quite interesting; there are different suppliers for that. Bauder also offers options for suspended floors with OSB on top, which I could also imagine using.
If your floor feels too cold so far and it is an older house anyway, from an aesthetic point of view, I could also imagine solid wood planks. As mentioned, there are underfloor heating solutions for those as well, which have already been discussed here.
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