ᐅ Subfloor Construction Without Screed for Solid Wood Planks – Experiences
Created on: 9 Nov 2020 19:04
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pagoni2020
My current plan is to have a standard concrete slab under the house; additional insulation is still possible.
Based on my experience with a house that has a basement, I had planned to lay a membrane on the raw subfloor (this time without a basement) as a moisture barrier. On top of that, I would install a joist or cross beam structure with loose-fill insulation in between (cork, perlite, hemp-light clay loose-fill; this is also what the contractor recommended).
I recently consulted a specialist company for these types of insulation materials, and they raised some concerns that the membrane on the raw subfloor might prevent moisture—potentially settling from indoor air in the worst case, through the wooden floorboards and insulation—from properly draining downward because of the membrane.
Their advice was to lay the joists directly on the membrane to protect the wood from direct contact with concrete and moisture, and to place the insulation directly on the raw subfloor instead.
In my opinion, however, this approach might carry the risk that residual moisture could rise from below into the insulation area, just reversing the problem.
One possible solution could be to use foam glass gravel when the concrete slab is first poured; however, I am not sure if my general contractor will implement this or if it actually makes sense.
I thought I had this issue figured out, but since there is no basement under the living areas in this build, it is making me reconsider. Ultimately, I want to avoid screed specifically because of moisture concerns.
Does anyone have more detailed experience or knowledge about this?
@Steffi33, you have a construction like this; could you share your exact setup (membrane, insulation, etc.)? Do you have a basement? What type of concrete slab do you have? What joist height did you use? Sorry for all the questions.
Based on my experience with a house that has a basement, I had planned to lay a membrane on the raw subfloor (this time without a basement) as a moisture barrier. On top of that, I would install a joist or cross beam structure with loose-fill insulation in between (cork, perlite, hemp-light clay loose-fill; this is also what the contractor recommended).
I recently consulted a specialist company for these types of insulation materials, and they raised some concerns that the membrane on the raw subfloor might prevent moisture—potentially settling from indoor air in the worst case, through the wooden floorboards and insulation—from properly draining downward because of the membrane.
Their advice was to lay the joists directly on the membrane to protect the wood from direct contact with concrete and moisture, and to place the insulation directly on the raw subfloor instead.
In my opinion, however, this approach might carry the risk that residual moisture could rise from below into the insulation area, just reversing the problem.
One possible solution could be to use foam glass gravel when the concrete slab is first poured; however, I am not sure if my general contractor will implement this or if it actually makes sense.
I thought I had this issue figured out, but since there is no basement under the living areas in this build, it is making me reconsider. Ultimately, I want to avoid screed specifically because of moisture concerns.
Does anyone have more detailed experience or knowledge about this?
@Steffi33, you have a construction like this; could you share your exact setup (membrane, insulation, etc.)? Do you have a basement? What type of concrete slab do you have? What joist height did you use? Sorry for all the questions.
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pagoni202010 Nov 2020 10:48sascha-t4-le schrieb:
That is interesting, unusual, and uncommon.
May I ask what advantages you expect from this floor construction?I’m not sure if there are any technical advantages, but I don’t see any disadvantages either. I am familiar with this system and have lived with it for a long time, always feeling comfortable. Since I currently live in a nice place equipped with underfloor heating, I can notice the difference and personally conclude that I don’t want underfloor heating. The main reason is the system’s slow response time and the resulting inability to quickly or individually adjust the temperature of single rooms.
In winter, we will often heat our largely open spaces with a wood stove plus infrared heating combined with photovoltaic power, that’s probably how it will be.
In the old house, for some reason, I had a hybrid solution with exposed joists, cork insulation filler, and screed without underfloor heating, and in hindsight, I definitely prefer the joisted floor with solid wood planks.
I’ve tried to inform myself as much as possible on this topic and still like a solution similar to what @Steffi33 has, even if I might consider a different insulation or build-up, but basically along the same principle; thanks again for the pictures and information, @Steffi33.
Not least, the numerous stressful discussions and also problems here with heat pumps and underfloor heating—such as pipe spacing, reluctance of heating contractors, and other technical issues—have made us decide on a system that we value for its simple and reliable operation.
It’s not exceptional, but probably rather uncommon.
Possible advantages: no additional cement in the house, no extra moisture, the floor can be relatively easily opened at any time, noticeably “softer” subfloor compared to glued parquet on screed, comfortable underfoot, and just a good overall feeling...
You will read a thousand different opinions here, so everyone should determine their own parameters. My alternative would have been heating with full-height tubular radiators, which are also available nowadays in very stylish designs—I had them painted as desired when I worked at an auto body shop.
Since, as you say, this is not very common currently, you really have to research and develop your own sense of it.
No solution here is ultimate.
I always advocate individuality and very personal preferences in design choices.
By the way, when I built in 1990, this was already uncommon; screed with or without underfloor heating was the standard, along with beech wood ceiling cladding as well as bay windows…
@pagoni2020 .. Those are exactly our reasons. The “soft” ground was especially important.. Little climbers often fall.. from all sorts of heights.. 😱.
In the other rooms (kitchen, bathrooms, hallway, utility room) we have underfloor heating (installed in screed) and natural stone.
In the other rooms (kitchen, bathrooms, hallway, utility room) we have underfloor heating (installed in screed) and natural stone.
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pagoni202010 Nov 2020 13:19Steffi33 schrieb:
@pagoni2020 .. Those are exactly our reasons. The “soft” subfloor played a particularly important role.. Little climbers often fall.. from all sorts of heights.. 😱.
In the other rooms (kitchen, bathrooms, hallway, utility room) we have underfloor heating (on screed) and natural stone.......older climbers too.... 😎Many years ago, I slipped on socks in my house, ended up horizontal in mid-air, and fell down two steps into the sunken living room. Nothing happened! Of course, that’s not a general argument, but I’m sure it would have been different with a floor directly on screed. There are always examples supporting one side or the other, but that’s how we’re doing it now. It looks like we will also install wooden flooring in the bathroom. We have decided against a wet underfloor heating system and will partially integrate some heating in the floor with supply water temperature, although I generally wouldn’t need underfloor heating under the wood.
What surprised me about modern underfloor heating is that tiled floors (currently) often feel quite cool, probably due to the low supply water temperature, which usually makes sense from a calculation standpoint.
In the end, so many options are possible… that’s exactly what makes it great.
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pagoni202010 Nov 2020 19:04HarvSpec schrieb:
Take a look at the Gutex system! It’s suitable for a smooth concrete ceiling. Thanks a lot, I checked it out, it looks good.
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hampshire10 Nov 2020 19:44sascha-t4-le schrieb:
May I ask what advantages you expect from this floor construction?If you want to install solid, large, and wide planks, this construction method is ideal. Simply placing them side by side and gluing them together won’t work.Similar topics