Breathable floors, limecrete or other optoins?
Discussion
c2mike said:
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.
Insulation isn't magic. It slows the rate at which heat is lost from a building; it doesn't stop it altogether.Yes, you may get away with it, if the rest of the structure is sufficiently breathable and/or well ventilated, but the 'pushing dampness toward the walls' argument is pretty much totally spurious (the external ground is the dampest bit, and the walls are sitting in that whatever you do), so you're paying a lot of money to take a risk that you don't need to take, IMO.
Snake oil.
jason61c said:
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.
...but is highly vapour permeable. Damp ground just creates damp air in the voids between the glass insulation, which the UFH will then draw into the building.Good, old-fashioned rockwool (and PIR) is resistant to capillary transmission of moisture, but you sure as hell still wouldn't use it without a vapour barrier in any situation where the cool side of the insulation wasn't thoroughly well ventilated to disperse the moisture.
Use a DPM (which also acts as a vapour barrier), and forget all this nonsense about 'breathable floors'. Solid ground floors DO NOT BREATHE - at least not in the direction you want them to.
http://limecrete.co.uk/limecrete-faq/
https://www.homebuilding.co.uk/renovating-old-floo...
https://www.homebuilding.co.uk/renovating-old-floo...
Edited by c2mike on Sunday 23 September 21:35
jason61c said:
The key point being the fact the floors are heated, I guess theres much less chance of damp anyway!?
You're not grasping the difference between damp and vapour, I think. No, the floor wouldn't be damp, but it will generate a lot of vapour within the insulated envelope, which then has to be dealt with if it is not to create problems elsewhere,jason61c said:
As I don't have a DPC, where would I edge the DPM to?
To the external walls, lapped up to floor level. As I've said (repeatedly), the external walls are sitting in damp external soil, anyway. Their base is 'damp' to some degree in any traditional building. nothing you're doing with a DPM on the inside will significantly worsen that. It's above floor/external ground level that breathability comes into play.Anyway, you've obviously convinced yourself that your proposed solution is correct, no matter what I say. I've got better things to be doing with my time than cajoling a horse to take a drink, having led him to the trough.
Do what you want - I'm oot.
Edited by Equus on Sunday 23 September 21:53
c2mike said:
The most important and valid thing said on that link is the opening sentence:the Homebuilding and renovating link said:
When renovating a period property you are likely to find yourself faced with floors that are less than ideal in terms of our modern expectations.
Old buildings worked differently, and to a lower standard than modern ones.Why do you think that there was a move (in period) to suspended timber ground floors in the better quality of property?
If you want modern levels of moisture control, you have to use modern technology.
the limecrete link said:
Why don’t you use a damp proof membrane?
The Recycled Foam Glass insulation layer regulates moisture. The floor is designed to be vapor permeable allowing moisture to travel and preventing it from being forced to walls.
Allows the moisture to travel where exactly? It won't go into the ground - that's where it's coming from. The Recycled Foam Glass insulation layer regulates moisture. The floor is designed to be vapor permeable allowing moisture to travel and preventing it from being forced to walls.
Bulls
t and doublespeak. Refer to my third post.... Like I said, I'm oot.jason61c said:
I do understand his posts.
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
it sounds like a lovely old house you have there thats stood for a very very long time? personally, id replicate whatever the original builders did that has let it stand for so long.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
Edited by jason61c on Sunday 23 September 21:01
i did a 1700 house a couple of years ago that had a dpc and concrete floor in it laid by some local 'expert builder' in 2013. damp merely coursed up the walls. so, i took the concrete up, levelled the floor back to dirt, sanded it and laid a pammet floor. damp gone.
insulation wise? probably crap. but its an old grade 2 listed house so i cant have everything.
jason61c said:
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.
Cob?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
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.
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.
jason61c said:
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.
You sound like you know what you are doing which is great - interestingly the advice I received regarding UFH was the opposite. There is so much misinformation around it pays to go to multiple sources before committing to doing anything on these type of houses.
You can see some photos here: https://www.pistonheads.com/gassing/topic.asp?h=0&...
Clay paint is great BTW if you've not tried it yet
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.
jason61c said:
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.
Sounds awesome. I still miss mine but they are definitely a labour of love. The character of places are worth it though.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:
CharlesdeGaulle said:
What's a pammet floor?
It's a traditional type of terracotta floor tile. Quite commonplace around my neck of the woods (Norfolk).As an alternate to your issue, if you are hell bent on sticking some system on the floor, you could leave a channel all the way around the internal walls and then build a suspended floor ontop. look on it like a internal french drain.
jason61c said:
the link said:
A modern floor design with a DPM and concrete may work well in a traditional building too if the groundwater is minimal, but all too often the capillary effect of the substrate draws groundwater to the underside of the floor slab where it accumulates.
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).
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