limecrete floors.

[robgil]

we have decided to scrap uf heating as we wont be able to dig down to the earth's core to meet building regs without the house falling down.
but we will be lifting the concrete floors and that nasty dpc and i also need somewhere to hide pipework , under the floor would be ideal.
so guys , limecrete floors , what did you do and more importantly , how much did it cost?

 

[Penners]

If you're going to be digging down that far, then surely you're deep enough into the planet's crust to install UFH, aren't you?

 

[robgil]

oh i dont know to be honest , i always thought ufh required a huge amount of insulating and a deep screed ontop of the slab where as just a slab with no ufh and no top screed requires just a sound base to rest on , or have i got that all wrong?

 

[MdB]

Building control will still want you to fit insulation in the floor I believe unless you have super insulation elsewhere and a heat pump.

Our underfloor heated floor was 150mm concrete, 100mm insulation, 75mm screed. Our neighbours unheated floor was 150mm concrete, 80mm insulation, 75mm screed I believe.

Regarding Limecrete, if you mix it yourself, Jewsons are currently doing Leca for £5.50 a 15kg bag +vat. Ask for Weber insulation fill. Mike Wye does it for £5.77 per 27Kg and does variable sizes which reduces the amount of lime required.

 

[fjpdesigns]

If you don't want to mix it yourself it may be worth trying this lot. I don't know anything about them but the are only a few miles from you.
www.limecrete.co.uk

 

[Tom]

We did a Limecrete floor with UFH on the whole of the ground floor. The depth required for the UFH part isn't much at all. The depth for a Limecrete floor comes from the amount of LECA needed to satisfy current building regs in terms of insulation. This depth is determined by the amount of external walls you have, the number and size of windows, thickness of walls etc. We bought all our LECA and Hydraulic Lime for the floors from Ty Mawr Lime and they did all the calculations for us

I'll try to fish out all the info if you like.

Jaqy

 

[robgil]

that would be most helpful jaqy , thankyou.
i was hoping i could get away with just replacing the existing cement with a lime based cement and call it a repair rather than a new floor , thus hopefully not needing to get building control involved. but i guess its not like for like so it will indeed be a new floor.

 

[Tom]

I wonder if you could argue this one? If you have a cement floor now, which will be pushing moisture up the walls, and you replace it with a breathable floor with better insulation and integral heating, surely this could be seen as an improvement? Would anybody argue against that?

We had no problems meeting current building regs; like I said, Ty Mawr worked it all out for us and their service was excellent I'll try my best to dig out the paperwork. Hopefully, it'll be tomorrow but if may not be :roll:

Jaqy

 

[Gareth Hughes]

I wonder if you could argue this one? If you have a cement floor now, which will be pushing moisture up the walls, and you replace it with a breathable floor with better insulation and integral heating, surely this could be seen as an improvement? Would anybody argue against that?

Yes, building control would, as you're removing the cement which magically protects the floor against being damp.
Sorry, it's been one of those days.

 

[Tom]

:roll: Yes, I should have realised that, Gareth :roll: I guess it depends on the Building Control person because the guy who came here was completely on our side and couldn't believe we were going to so much effort to protect a house that isn't listed. Hopefully, Robgil will get someone just as understanding.

Jaqy

 

[lou]

We have bought a Welsh stone farmhouse which has stone flags on what looks like earth. We also need to remedy considerable damp problems and would like to install underfloor heating on limecrete floors. Can anyone suggest whether this is going to be possible / have experience of this? How can you tell if the walls will be made unstable and, also, can you use ufh under what might be very thick flags? Lots of other questions but would welcome views on these issues.

 

[MdB]

Hi Lou, welcome to the forum.

I would first find out why you are suffering from damp. If the floor is damp because of a high water table and you dig it out and install limecrete, you will still end up with a damp floor. It's good for letting the moisture pass through it and evaporate but then so does dirt. It isn't a magic fix.

Digging out a floor for underfloor heating using insulating limecrete will need at least 400mm to meet the latest regs (I believe - it could be more!) so yes it is likely to undermine the walls if you don't dig it out correctly. It could well be a job that requires a structural expert to look at it. These people are the experts on limecrete so it is worth speaking to them. http://www.limecrete.org.uk/

My (concrete - sorry) underfloor heating has 75mm of screed on top of the pipes. Flag stones are not going to be worse than this. They will act as a huge heat sink which will mean that it will take a few days for the house to heat up / cool down. Ours can change temperature by about 2 deg C per day.

 

[Gervase]

Absolutely problem with UFH on limecrete, and thick flags are not a problem - the thickest I've worked with were two inches (and they were monsters to move). A stone house is unlikely to have foundations, so make sure whoever digs out the floor knows exactly what they're doing otherwise your house could collapse like this Welsh stone house:

It makes a nice job for me, but it's not very nice for the householder!
The damp could have a number of causes - poor guttering, poor drainage, inappropriate soil levels, cement render, high water table; it's not something that can be easily diagnosed over the internet.

 

[Penners]

Good grief! Did that really collapse, or did someone have fun with a wrecking ball?

 

[Gervase]

Genuine collapes - builders were digging for an extension and dug straight down instead of on the batter. The house is built on compacted sand, and one cloudburst later, disaster.
It's now back up, with traditional rubble-stone walls and a more sympathetic extension, and looks -even though I say so myself - fabulous.
I need to take some more pix, but here's a couple: