Breathable floors, limecrete or other optoins?
Discussion
Just about to start on a a major part of restoration.
I'm all set to go down this route
http://dreieck.co.uk/renovation-heritage-old-build...
using
https://www.mikewye.co.uk/product/foam-glass-insul...
I'll be laying UFH in it. 150mm of insulation, 100mm slab with the pipes in.
My only worry is how long it might be before I can put sandstone flags down on top. Part of my says to put the slabs down while the floors quite 'green' still?
I've about 65 sq M to do.
Any other options i've missed? I have no real foundations and do not have a DPC.
I'm all set to go down this route
http://dreieck.co.uk/renovation-heritage-old-build...
using
https://www.mikewye.co.uk/product/foam-glass-insul...
I'll be laying UFH in it. 150mm of insulation, 100mm slab with the pipes in.
My only worry is how long it might be before I can put sandstone flags down on top. Part of my says to put the slabs down while the floors quite 'green' still?
I've about 65 sq M to do.
Any other options i've missed? I have no real foundations and do not have a DPC.
Gooose said:
I can remember a grand design episode where this was used, went horribly wrong in the end, I think due to the cold but they ended up putting carpet and stuff on top so was a bit of a waste of time really!
I re-watched this episode just the other day. It was the one where the architect was keen on using materials that the owner and contractors had no knowledge of.Lime slab was a disaster and turned to dry porridge due to the cold weather.
With that in mind, starting the job now and maybe laying the lime slab during the frost and snow period would be just asking for trouble.
Personally, I think that the concept is founded on a fundamental misunderstanding of how things work, and is a really, incredibly bad idea with UFH.
I wouldn't touch it with the longest, s
ttiest bargepole I could find - I'd lay a DPM below the UFH and to hell with breathability on the floor.
Clue: ask yourself where it's breathing to exactly.
I wouldn't touch it with the longest, s
ttiest bargepole I could find - I'd lay a DPM below the UFH and to hell with breathability on the floor.Clue: ask yourself where it's breathing to exactly.
Equus said:
Personally, I think that the concept is founded on a fundamental misunderstanding of how things work, and is a really, incredibly bad idea with UFH.
I wouldn't touch it with the longest, sttiest bargepole I could find - I'd lay a DPM below the UFH and to hell with breathability on the floor.
Clue: ask yourself where it's breathing to exactly.
Can you explain why you think its wrong? It breathes through the stone, as floors have done for 100's of years.I wouldn't touch it with the longest, s
ttiest bargepole I could find - I'd lay a DPM below the UFH and to hell with breathability on the floor.Clue: ask yourself where it's breathing to exactly.
Why lay a DPM and push any moisture back into the walls again?
jason61c said:
Can you explain why you think its wrong? It breathes through the stone, as floors have done for 100's of years.
Why lay a DPM and push any moisture back into the walls again?
Breathe in. Hold your breath. Now breath in some more. Hold your breath. Continue to repeat, but have a friend or relative standing by to call you an ambwillans....Why lay a DPM and push any moisture back into the walls again?
At risk of stating the bloody obvious, breathing is a two way process.
Yes, it breathes in through the stone, as floors have done for 100's of years (leaving the floors continuously damp, for 100's of years, until we invented DPM's), but where does it breathe out to?
Breathable structures work because when it's warm and dry outside, they pull the moisture that's generated inside the building out and disperse it to external atmosphere. When it's cold and damp outside, they absorb some of that moisture into the structure, but it's partly held at bay by the fact that you're heating internally, which lowers the relative humidity of the internal air, so that it can absorb the incoming moisture as vapour (which you then disperse by ventilation or natural air leakage from the dwelling).
'Breathable' floors can breath in, but they can never breath out, because there's an infinite mass of permanently damp subsoil below them.
UFH will simply act to continuously wick the moisture from that subsoil into the building, which then adds to the burden of the ventilation and those elements of the structure that can genuinely (2-way) breathe.
Equus said:
Breathe in. Hold your breath. Now breath in some more. Hold your breath. Continue to repeat, but have a friend or relative standing by to call you an ambwillans....
At risk of stating the bloody obvious, breathing is a two way process.
Yes, it breathes in through the stone, as floors have done for 100's of years (leaving the floors continuously damp, for 100's of years, until we invented DPM's), but where does it breathe out to?
Breathable structures work because when it's warm and dry outside, they pull the moisture that's generated inside the building out and disperse it to external atmosphere. When it's cold and damp outside, they absorb some of that moisture into the structure, but it's partly held at bay by the fact that you're heating internally, which lowers the relative humidity of the internal air, so that it can absorb the incoming moisture as vapour (which you then disperse by ventilation or natural air leakage from the dwelling).
'Breathable' floors can breath in, but they can never breath out, because there's an infinite mass of permanently damp subsoil below them.
UFH will simply act to continuously wick the moisture from that subsoil into the building, which then adds to the burden of the ventilation and those elements of the structure that can genuinely (2-way) breathe.
did you look at the geocell insulation!?At risk of stating the bloody obvious, breathing is a two way process.
Yes, it breathes in through the stone, as floors have done for 100's of years (leaving the floors continuously damp, for 100's of years, until we invented DPM's), but where does it breathe out to?
Breathable structures work because when it's warm and dry outside, they pull the moisture that's generated inside the building out and disperse it to external atmosphere. When it's cold and damp outside, they absorb some of that moisture into the structure, but it's partly held at bay by the fact that you're heating internally, which lowers the relative humidity of the internal air, so that it can absorb the incoming moisture as vapour (which you then disperse by ventilation or natural air leakage from the dwelling).
'Breathable' floors can breath in, but they can never breath out, because there's an infinite mass of permanently damp subsoil below them.
UFH will simply act to continuously wick the moisture from that subsoil into the building, which then adds to the burden of the ventilation and those elements of the structure that can genuinely (2-way) breathe.
so I dpm and push moisture into walls?
jason61c said:
did you look at the geocell insulation!?
so I dpm and push moisture into walls?
Yes, I looked at the geocell insulation.so I dpm and push moisture into walls?
And no, DPM's don't 'push' moisture anywhere. They hold moisture under that part of the floor they cover, but since there's a limitless supply of the stuff (including in the large expanse of damp external ground around a building) that really makes no difference.
It's pseudo-scientific b
ks from bunny-hugging, lentil-weaving hippies who don't know what they are talking about (ably supported by marketing parasites who are trying to sell you an expensive product you don't need).
Equus said:
Yes, I looked at the geocell insulation.
And no, DPM's don't 'push' moisture anywhere. They hold moisture under that part of the floor they cover, but since there's a limitless supply of the stuff (including in the large expanse of damp external ground around a building) that really makes no difference.
It's pseudo-scientific bks from bunny-hugging, lentil-weaving hippies who don't know what they are talking about (ably supported by marketing parasites who are trying to sell you an expensive product you don't need).
I bet you don't agree with lime plaster either do you And no, DPM's don't 'push' moisture anywhere. They hold moisture under that part of the floor they cover, but since there's a limitless supply of the stuff (including in the large expanse of damp external ground around a building) that really makes no difference.
It's pseudo-scientific b
ks from bunny-hugging, lentil-weaving hippies who don't know what they are talking about (ably supported by marketing parasites who are trying to sell you an expensive product you don't need).They do 'hold', until it finds somewhere to go. Where do you think it should go? Having sealed floors have made walls wet.
jason61c said:
I bet you don't agree with lime plaster either do you
They do 'hold', until it finds somewhere to go. Where do you think it should go? Having sealed floors have made walls wet.
Yes, I agree with lime plaster. Did you bother to read, and more importantly understand what I have written above? They do 'hold', until it finds somewhere to go. Where do you think it should go? Having sealed floors have made walls wet.
I'll try again:
Walls can breath both ways: to external air, when the external relative humidity is lower than the internal, or to internal air (which can then be dispersed by ventilation). Lime plaster and other breathable materials work just fine, therefore, because at least some of the time they are capable of breathing in the right direction.
Floors can only ever draw moisture one way: into the building. The ground is always damp (beyond the top couple of inches), even in the driest summers we experience in the UK.
Not having a DPC, combined with a structural dew point that is close to the internal face of the wall is what makes walls wet. The soil they sit on and in is going to be damp whatever you do with the floor... but if you make the floor 'breathable', it will just allow more moisture in, increasing the internal RH and worsening the problem.
As with all things involving moisture, they will always follow the laws of physics. You can't push water up a wall unless you have hydrostatic pressure, which you don't have unless you're in a swimming pool.
In answer to your original question, I presume the lime will need CO2 to cure, whilst your slabs wont preclude this I think it's reasonable to say the cure would be greatly protracted by them.
In answer to your original question, I presume the lime will need CO2 to cure, whilst your slabs wont preclude this I think it's reasonable to say the cure would be greatly protracted by them.
C Lee Farquar said:
As with all things involving moisture, they will always follow the laws of physics. You can't push water up a wall unless you have hydrostatic pressure, which you don't have unless you're in a swimming pool.
In answer to your original question, I presume the lime will need CO2 to cure, whilst your slabs wont preclude this I think it's reasonable to say the cure would be greatly protracted by them.
Its the time thats the problem. In answer to your original question, I presume the lime will need CO2 to cure, whilst your slabs wont preclude this I think it's reasonable to say the cure would be greatly protracted by them.
Part of me is thinking, use the foamed glass but use concrete instead! As the house is always heated now, it should be much better anyway, or have a hybrid solution where I use limecrete for a 1x7m strip in a room where the floor is at risk to damp as the ground levels are higher outside.
Thinking further on this
I had someone fill a cavity below the dpc with lime mortar when I wasn't looking.
Although, in theory, it should have been able to 'breathe' through the brick/lime built outer leaf, it didn't. We had to take the wall down 18 months later and the mortar in the cavity was like damp, compacted sand. It hadn't cured at all.
I had someone fill a cavity below the dpc with lime mortar when I wasn't looking.
Although, in theory, it should have been able to 'breathe' through the brick/lime built outer leaf, it didn't. We had to take the wall down 18 months later and the mortar in the cavity was like damp, compacted sand. It hadn't cured at all.
C Lee Farquar said:
You can't push water up a wall unless you have hydrostatic pressure, which you don't have ...
...or capillary action which you do.Despite the ramblings of the odd tinfoil-hatter like Jeff Howell, mortar is porous and almost always shows some degree of capillary action (and usually much more pronounced with lime mortars - which is why they are 'breathable' in the first place).
Also, remember that water vapour, rather than liquid water is either responsible for, or contributes significantly to, the majority of damp related structural issues (including rising damp), and vapours exert their own pressure.
...and if someone were to ask me the best way of generating large amounts of water vapour, I'd probably tell them to take a large mass of permanently damp material (subsoil will do just fine
) and gently warm it over the largest surface area possible, for example by using a nice, big, looped grid heating element such as is employed in an underfloor heating system...OP - you still don't seem to have understood what equus has explained in detail above.
A breathable floor will achieve nothing other than allow the infinite amount of moisture available from the soil into your house. Heating that continually damp surface to increase the evaporation rate will have the windows streaming!
Forget lime in the floor and lay a conventional floor with dpc. If the ground against external walls is wet or too high either dig out as much as possible or even run french drains around the perimeter.
A breathable floor will achieve nothing other than allow the infinite amount of moisture available from the soil into your house. Heating that continually damp surface to increase the evaporation rate will have the windows streaming!
Forget lime in the floor and lay a conventional floor with dpc. If the ground against external walls is wet or too high either dig out as much as possible or even run french drains around the perimeter.
We recently had a similar glass / lime / water heated floor installed as recommended by our architect. 12 months in, no signs of dampness (previous floor was mostly brick on earth and was damp). The new floor is same bricks re-laid with the lime, pipes and glass below.
An important point is that the floor is highly insulated from below, so the suggestion that you are creating water vapour in the room by heating the ground is hard to believe.
We were told that a non-breathable floor would create imbalance and push dampness towards the walls. In a house that has stood for over 400 years, that makes sense to me - let it breathe!
An important point is that the floor is highly insulated from below, so the suggestion that you are creating water vapour in the room by heating the ground is hard to believe.
We were told that a non-breathable floor would create imbalance and push dampness towards the walls. In a house that has stood for over 400 years, that makes sense to me - let it breathe!
I do understand his posts.
What I was pointing out/trying to say is that its sat on the foamed glass insulation, so isn't in touch with the damp floor.
so as a side thought, concrete on most of the floors, a bit of a hybrid?
Its an old house there's nice natural air movement.
I want to do the right thing for the house, just as importantly, I want to do the right thing for the family, so not having them at the MIL for a month
I've already put a french drain round the house, lowered ground levels as much as possible, removed the concrete render that was on the stone base of the cob walls, removed internal gypsum plaster and plasterboard.
What I was pointing out/trying to say is that its sat on the foamed glass insulation, so isn't in touch with the damp floor.
so as a side thought, concrete on most of the floors, a bit of a hybrid?
Its an old house there's nice natural air movement.
I want to do the right thing for the house, just as importantly, I want to do the right thing for the family, so not having them at the MIL for a month
I've already put a french drain round the house, lowered ground levels as much as possible, removed the concrete render that was on the stone base of the cob walls, removed internal gypsum plaster and plasterboard.
Edited by jason61c on Sunday 23 September 21:01
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