Limecrete floor - interesting advice re breathability

[margatedan]

I had a chat with a technician from one of the main providers of limecrete floor systems as I was curious about possible surfaces for our floor. We've had exposed limecrete for a few years and its great but its starting to get some wear and it would be nice to spruce up somehow. I always assumed one shouldn't lay a floor that prevents permeability. But the very helpful person said that this is a myth and, after providing floors for a long time and seeing the long term effects, limecrete can be covered with something non-breathable. This is because the damp proofing occurs way down in the glassfoam gravel bit. So you can paint it or marmoleum or whatever. The person was very knowledgeable and its a reputable company but I was still surprised at this so just wanted to come here for a second opinion!

 

[almostatmywitsend]

I had a chat with a technician from one of the main providers of limecrete floor systems as I was curious about possible surfaces for our floor. We've had exposed limecrete for a few years and its great but its starting to get some wear and it would be nice to spruce up somehow. I always assumed one shouldn't lay a floor that prevents permeability. But the very helpful person said that this is a myth and, after providing floors for a long time and seeing the long term effects, limecrete can be covered with something non-breathable. This is because the damp proofing occurs way down in the glassfoam gravel bit. So you can paint it or marmoleum or whatever. The person was very knowledgeable and its a reputable company but I was still surprised at this so just wanted to come here for a second opinion!

Interesting... which supplier?

 

[Kearn]

Absolutely true.

RFG is a European product, they use it as a hardcore type 1 replacement only. Then pop a DPM and concrete slab over… exactly what I’ve just done on our modern extension.

Limecrete really doesn’t do any moisture management.

At best a decimal point percentage of groundwater moisture that is present may make itself to the slab as vapour, but the RFG acts as a capillary break for ground water and it never should get more than 10-20% of the depth if specced to the correct depth.

So yes, pop what you like over it.

Limecrete does have other benefits, and there are reasons to use it instead of a more modern slab/screed, but the myth of a breathable floor isn’t one!

If you have an exposed limecrete slab, you can do your own test. Lay some plastic sheeting/thick plastic bags on the floor overnight weighted down. See if there’s any darkness or dampness under them. Precisely the same test to show that an old tile or slab floor on earth should t have impermeable materials covering it.

 

[margatedan]

Thank you - fascinating. Yes - we've two large squres of marmoleum down as a temporary measure in the kitchen - looks v nice actually - and yes, no trapped moisture at all or evidence of it. Curious how so much discourse around limecrete still suggests a permeable top layer (limestone, clay tiles etc).

 

[Kearn]

Thank you - fascinating. Yes - we've two large squres of marmoleum down as a temporary measure in the kitchen - looks v nice actually - and yes, no trapped moisture at all or evidence of it. Curious how so much discourse around limecrete still suggests a permeable top layer (limestone, clay tiles etc).

People will adamantly tell you floors have to be ‘breathable’ and that’s what limecrete is and that’s how the system works, without knowing how the system actually works!

The cynic in me would point out that those pushing limecrete floors are the same folks who run a business selling lime…!