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Penners
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Hang on - let's think about this.
We presume that coated leca won't soak up moisture and uncoated will. But what difference does that make to your floor? So far as my addled brain can appreciate, the only difference will be the amount of moisture that the floor can actually hold. (I take it that we're talking about a floor with no DPM).
So, assuming your floor absorbs moisture from the subsoil, the coated leca floor will become saturated (ie: in balance with the subsoil moisture content) on, for the sake of argument, Monday. The uncoated leca floor will hold more moisture so it will take a bit longer to saturate - it might not reach saturation until Friday.
But in the end you still have a floor which is saturated to the extent that it is in balance with the subsoil, and (assuming that your matrix is lime in both cases) will breathe out moisture vapour. In neither cases will the aggregate be exposed to the air, so I don't see that the coated leca will assist the floor's breathability, as compared with the uncoated.
Obviously if it's just insulation you're after, then coated will be best.
The above reasoning may be ludicrously flawed.
We presume that coated leca won't soak up moisture and uncoated will. But what difference does that make to your floor? So far as my addled brain can appreciate, the only difference will be the amount of moisture that the floor can actually hold. (I take it that we're talking about a floor with no DPM).
So, assuming your floor absorbs moisture from the subsoil, the coated leca floor will become saturated (ie: in balance with the subsoil moisture content) on, for the sake of argument, Monday. The uncoated leca floor will hold more moisture so it will take a bit longer to saturate - it might not reach saturation until Friday.
But in the end you still have a floor which is saturated to the extent that it is in balance with the subsoil, and (assuming that your matrix is lime in both cases) will breathe out moisture vapour. In neither cases will the aggregate be exposed to the air, so I don't see that the coated leca will assist the floor's breathability, as compared with the uncoated.
Obviously if it's just insulation you're after, then coated will be best.
The above reasoning may be ludicrously flawed.
tobydog
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Interesting. This site suggests that the coating stops to movement of moisture whereas others suggest it limits the movement.
http://www.heritageltd.com/limecrete.htm
http://www.heritageltd.com/limecrete.htm
Penners
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Yes, I see what you mean, Toby. But so far as I can see, they're talking about a loose fill dry layer of leca below the wet floor fill. I can certainly see the sense of using coated leca there.
My thoughts above referred to leca used as an aggregate within a lime mortar matrix. In that case I was postulating that the matrix provides a migration route for the damp, regardless of whether the aggregate will or will not absorb moisture. But, as I said, these are amateur ramblings... :?
My thoughts above referred to leca used as an aggregate within a lime mortar matrix. In that case I was postulating that the matrix provides a migration route for the damp, regardless of whether the aggregate will or will not absorb moisture. But, as I said, these are amateur ramblings... :?
tobydog
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All ramblings appreciated as I have a situation coming up shortly where I will need to apply this 'logic'. As you might recall, I have dug down between the front edge of our old kitchen concrete floor and the plynth wall. It's currenlty drying out very slowly. Thankfully the builders left a gap that they filled with sand and small rubble but over 10ft of length it goes from 100mm wide down to nothing. It's about 300mm deep. I really dont want to take out any more of the floor to make the gap wider unless absolutely necessary. I've come to the conclusion that I can't just fill it with limecrete because I dont have enough surface area open to the air for depth of the gap. Think of the gap as a very narrow slice of brie. I plan to fill the first 250mm of depth with uncoated leca of mixed size and then top it off with uncoated leca mixed with NHL2 for the other 50mm. Maybe even 275/25. It wont need to carry any weight.
I know someone else suggested this on a previous thread but I can recall who it was or how it ended up.
The gap between the plynth wall and the sole plate I will simply rebuild first with soft reds but I'm not sure on the mortar mix. The majority of the plynth will still be sitting below floor level, will unlikely dry our completely, and will have limited surface area to the air. I'll try and take some photos over the weekend.
I know someone else suggested this on a previous thread but I can recall who it was or how it ended up.
The gap between the plynth wall and the sole plate I will simply rebuild first with soft reds but I'm not sure on the mortar mix. The majority of the plynth will still be sitting below floor level, will unlikely dry our completely, and will have limited surface area to the air. I'll try and take some photos over the weekend.
Penners
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It may have been MdB. He's knows about this stuff (which is more than can be said for me).tobydog said:
Penners
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I suppose that risk could exist, Rob, but don't you think that the loose-fill leca will be of some moderate help in minimising damp? It will, after all, allow some air circulation, albeit within a confined space.
MatthewC
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I actually laid a limecrete floor this time last year (a whole year ago - where has it gone?). The design was from Mike Wye. The LECA provides the insulation, so the more the better. We had 200mm of coated LECA on a breathable membrane at the bottom of a dirty great hole in the floor; we then added another breathable membrane and on that we put the slab of hydraulic lime (NHL5) and uncoated LECA - I presumed that the uncoated made for a better mix - followed by the bed and flagstones, so we had a depth of 375mm total.
In a sense the LECA does act like a DPM, as the shape of the LECA prevents capillary action so any actual water does not rise up. But it's also breathable so it allows water vapour to go up through it, through the breathable floor and evaporate as one would hope. I do not think that it forces moisture out to the walls at all, nor will the air circulate in it.
Either see my blog for April last year (blue button on right), or else see the Mike Wye website http://www.mikewye.co.uk/limecrete.htm, where the "floor case study" is my floor with more photos than the blog.
My floor has been fine in this last year - we have had no trouble or worries at all and have eliminated the remainder of the dampness in the house. I don't think that the coated LECA will absorb water at all, but I will go outside now and try a few experiments on some leftovers.
Matthew
In a sense the LECA does act like a DPM, as the shape of the LECA prevents capillary action so any actual water does not rise up. But it's also breathable so it allows water vapour to go up through it, through the breathable floor and evaporate as one would hope. I do not think that it forces moisture out to the walls at all, nor will the air circulate in it.
Either see my blog for April last year (blue button on right), or else see the Mike Wye website http://www.mikewye.co.uk/limecrete.htm, where the "floor case study" is my floor with more photos than the blog.
My floor has been fine in this last year - we have had no trouble or worries at all and have eliminated the remainder of the dampness in the house. I don't think that the coated LECA will absorb water at all, but I will go outside now and try a few experiments on some leftovers.
Matthew
I don't understand this thread.
My house was built in pre-leca days, where the only options seemed to have been wooden (suspended) floors or flags/pamments laid straight on the earth.
My hall and breakfast-room have flags and pamments respectively and neither are damp.
So what sort of conditions would necessitate going to all the trouble and expense of the leca/limecrete route?
My house was built in pre-leca days, where the only options seemed to have been wooden (suspended) floors or flags/pamments laid straight on the earth.
My hall and breakfast-room have flags and pamments respectively and neither are damp.
So what sort of conditions would necessitate going to all the trouble and expense of the leca/limecrete route?
Under floor heating Moo or just the idea of insulating a bathroom floor. I would love to put my floorbricks down on a bed of sand and not worry about it but I have decided it's best to unsulate where possible.
Does the crushed glass insulation have any capillary action?
My floor is very damp , when it rains a puddle appears in the trench I dug for the foul drain. It soon dissapears after the rain and may be because I have no guttering up yet
but with clay lump I dont want to take any chances, It will be expencive and time consuming to put right if the floor doesnt work.
Does the crushed glass insulation have any capillary action?
My floor is very damp , when it rains a puddle appears in the trench I dug for the foul drain. It soon dissapears after the rain and may be because I have no guttering up yet
but with clay lump I dont want to take any chances, It will be expencive and time consuming to put right if the floor doesnt work.
Zebra
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There was something on it here:tobydog said:
http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=12010&p=158240&hilit=+limecrete#p158240
Zebra
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tobydog said:
I don't think brie would make a very good insulator tobydog. Nor, after a few months, would it be breathable.
tobydog
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Well, here is my slice of brie! It doesn't actually smell anymore but it did when I first removed the cement, the rotten parts of the sole plate and the crumbling part of the plynth. Most of what I have removed came out in the hoover and dustpan.
It still needs a couple of months to continue drying out but I'll be repointing the existing plynth and rebuilding the top part first. Recommendations for the type of lime mortar I should be using? I will be taking it up to the remaining sole plate using a combination on soft reds and tile but I don't plan to put in any kind dpc (only traditional considered). I had considered slate but the floor level is so high that inserting slate will leave little surface area below to breath. This will then remain unrendered for the rest of the summer. I thought that if I built up the plynth while it was still slightly damp then the mortar would go off slower. Does this make sense?
As for the gap, you can see it goes from 100mm at one end down to nothing at the other. 300mm deep. I'll leave this open while the plynth is drying. What about just filling it with leca to the top? It's never going to walked on or have furniture sit on it. I can then leave it to dry indefinitely. I'm sure the Dyson will create some casualties. By the way, the outside of the plynth is encased in about 150mm of cement that goes down a metre :shock:. That's staying put for the foreseable future as it could be holding the house up. Drying out from inside only.
Other parts of the room with exposed plynth to a higher level are now completely and I'll simply render that in NHL2 (?) and fill the small shallow gap in front of that with the same.
Thoughts appreciated.
It still needs a couple of months to continue drying out but I'll be repointing the existing plynth and rebuilding the top part first. Recommendations for the type of lime mortar I should be using? I will be taking it up to the remaining sole plate using a combination on soft reds and tile but I don't plan to put in any kind dpc (only traditional considered). I had considered slate but the floor level is so high that inserting slate will leave little surface area below to breath. This will then remain unrendered for the rest of the summer. I thought that if I built up the plynth while it was still slightly damp then the mortar would go off slower. Does this make sense?
As for the gap, you can see it goes from 100mm at one end down to nothing at the other. 300mm deep. I'll leave this open while the plynth is drying. What about just filling it with leca to the top? It's never going to walked on or have furniture sit on it. I can then leave it to dry indefinitely. I'm sure the Dyson will create some casualties. By the way, the outside of the plynth is encased in about 150mm of cement that goes down a metre :shock:. That's staying put for the foreseable future as it could be holding the house up. Drying out from inside only.
Other parts of the room with exposed plynth to a higher level are now completely and I'll simply render that in NHL2 (?) and fill the small shallow gap in front of that with the same.
Thoughts appreciated.
