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.
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, 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.
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?
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?
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.
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.
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
Herbs said:
Cob?
How thick are the walls? I had a 1703 Cob farmhouse I purchased in 2010 that I had to strip back to cob inside and out as the previous owners tanked the walls inside and out resulting in damp pushing through eventually at head height and took 2 months to dry out once fully exposed - there are some pictures on here actually.
The last thing I would have done with a Cob building is to install underfloor heating. Cob is a fantastic material but works by being damp - the problems come from being either too damp which can cause it to collapse, conversely if they are too dry, they can just crumble as well.
I's strongly recommend speaking to Nigel at The Lime Centre and get their advice on whether you should do it or not and if so, how best to install so you don't damage the building or cause issues for yourself.
600-900mm thick.How thick are the walls? I had a 1703 Cob farmhouse I purchased in 2010 that I had to strip back to cob inside and out as the previous owners tanked the walls inside and out resulting in damp pushing through eventually at head height and took 2 months to dry out once fully exposed - there are some pictures on here actually.
The last thing I would have done with a Cob building is to install underfloor heating. Cob is a fantastic material but works by being damp - the problems come from being either too damp which can cause it to collapse, conversely if they are too dry, they can just crumble as well.
I's strongly recommend speaking to Nigel at The Lime Centre and get their advice on whether you should do it or not and if so, how best to install so you don't damage the building or cause issues for yourself.
cob doesn't work by being 'damp' from my understanding. I've even rebuilt part of a cob wall with cob.
We've had walls stripped for about 3 years now.
Every 'expert' has said that UFH is great for these houses.
It'd be great to see your pics? Sounds like a great project. Luckily they never tried tanking the walls, just cement render on the stone plinth and horrid gypsum render on the inside.
Great thread.
Our base is from the 15-1600's, was a long barn, converted in a '3 room cross passage', then the Georgians came along and added a proper first floor, followed by the victorians who boxed the place up into lots of square rooms.
Like yourself, all cob walls exposed, parts rebuit where it had become saturated, numerous lintels replaced where the originals had rotted away etc etc.
a lot of the time I hate the place for fighting so hard.
Our base is from the 15-1600's, was a long barn, converted in a '3 room cross passage', then the Georgians came along and added a proper first floor, followed by the victorians who boxed the place up into lots of square rooms.
Like yourself, all cob walls exposed, parts rebuit where it had become saturated, numerous lintels replaced where the originals had rotted away etc etc.
a lot of the time I hate the place for fighting so hard.
Equus said:
The simple answer to that one is to use a substrate with minimal capillary effect. Clean brick hardcore would do the job pretty well.
And of course you should be taking measures externally to ensure that groundwater around the building footprint is minimal... all the fancy floor design in the world wont stop the walls wicking up groundwater if their bases are piss wet through on the outside (as I've said previously).
Every measure possible has been done now(previously stated). All new drains, french drains where possible, correct render used, stone plinth exposed, ground levels altered(2 foot drop at one part and pushed back 4M).And of course you should be taking measures externally to ensure that groundwater around the building footprint is minimal... all the fancy floor design in the world wont stop the walls wicking up groundwater if their bases are piss wet through on the outside (as I've said previously).
Equus said:
Then you shouldn't have a problem.
...In which case, I wouldn't be worrying about questionable, snake-oil solutions on top of those measures which might actually make things worse.
With UFH, I'd be using a DPM... no question about it. All a breathable floor will do is allow a nice, easy route for the vapour generated by the heat soak from of the UFH (even despite insulation) to find its way into the building.
No I shouldn't. Its a belt and braces approach ...In which case, I wouldn't be worrying about questionable, snake-oil solutions on top of those measures which might actually make things worse.
With UFH, I'd be using a DPM... no question about it. All a breathable floor will do is allow a nice, easy route for the vapour generated by the heat soak from of the UFH (even despite insulation) to find its way into the building.
Just to update this thread.
Went with a limecrete floor, so glad I did.
Floor dried very well, zero cracking, was warm to the feel. The one bit of remaining damp vanished, So no DPC or membranes anywhere, perfectly dry house, just as it was built I guess. Even when we've had weeks of rain. This was before any UFH was used. humidity is much lower also. Win/Win.
Forced action mixer was the best thing ever for mixing the lime compared to a tumble mixer.
32 tonnes dug out the house(mini digger!), about 12 tonnes back in.
Anyone with an older house, its well worth doing it if you need to.
Went with a limecrete floor, so glad I did.
Floor dried very well, zero cracking, was warm to the feel. The one bit of remaining damp vanished, So no DPC or membranes anywhere, perfectly dry house, just as it was built I guess. Even when we've had weeks of rain. This was before any UFH was used. humidity is much lower also. Win/Win.
Forced action mixer was the best thing ever for mixing the lime compared to a tumble mixer.
32 tonnes dug out the house(mini digger!), about 12 tonnes back in.
Anyone with an older house, its well worth doing it if you need to.
C Lee Farquar said:
Glad it's working for you.
For balance though I related many of the points Equus made to a customer who was considering a limecrete floor. They decided to have concrete, have had no damp and are very happy. Also a win/win.
Yep, I did really consider all options. Its the long term that held me back going for concrete, issues seem to take years to come through.For balance though I related many of the points Equus made to a customer who was considering a limecrete floor. They decided to have concrete, have had no damp and are very happy. Also a win/win.
C Lee Farquar said:
I recall from a training course I went on many years ago that lime plaster should be regarded as a sacrificial coat, and I would think the same would be true of a floor without a membrane.
If the wall/floor is 'breathing' you will get salt deposits, which over the years will build up and cause their own problems. However this may take decades or centuries so I wouldn't be losing any sleep.
Yep, correct for lime plaster, however the floor is NHL5, which when used in this application doesn't have any issues.If the wall/floor is 'breathing' you will get salt deposits, which over the years will build up and cause their own problems. However this may take decades or centuries so I wouldn't be losing any sleep.
Its a nice way of building.
papante said:
Good to know that 2 people from here actually put the theory of Limecrete floor into practice and the results are as expected. Lot of theory and much more experts around, but at the end what matters is the result.
there's a few locally who aren't on here that have done it also. all with the same positive results.Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff