Limecrete floor with LECA

[Sikes]

I have 2 very small areas (alcoves, 40cmx70cm) that I want to put a limecrete floor into. I'm going to use LECA due to cost but having never used it before (or laid a limecrete floor), I wondered if the following is ok for the aggregate base and in the limecrete mix:
https://www.amazon.co.uk/10-20mm-Lightw ... 083QP7NGH/

I keep seeing mention of coated and uncoated, which is making me doubt I have the right product?

[Isabellah]

I would like to knew this, as I want limecrete floor too. Leca seems to be good enough but I would like to know some reviews from people who have ever used LECA

[a twig]

A quick search for LECA on this forum will avail you of the many experiences that residents of this parish have had with LECA and limecrete.

[Sikes]

I have searched for LECA and there are plenty of mentions. I'm lacking in knowledge so I suppose what I need to know is:

• The LECA that I have purchased from Amazon, I'm assuming its uncoated. Is that ok for the insulation layer?

• If not, where can I get samller quantities of coated LECA? I can only find suppliers who deliver large quantities.

This video mentions coated and uncoated: https://www.youtube.com/watch?v=0SxkdgGq5a0 Is it a requirement or nice to have?

[MatthewC]

I used LECA almost 11 years ago. I found it quite difficult to use as you can't tamp it because it shatters. I found that the base layer of loose LECA moves very easily when laying the mortar bed onto a membrane with the LECA underneath. I think we used a lot more mortar than expected for this reason.

I recall having a question about the coated and uncoated LECA, and (as many other times) I asked Mike Wye about this. (They gave free advice to anyone who had done one of their courses. I don't know if that is still done, but they helped me without question last autumn.)

My blog tells me (as I had forgotten their answer) that the Mike Wye limecrete floor design "uses the coated version of LECA as a loose lay foundation; this allows the floor to breathe but does not allow any water to rise by capillary action. On top of this the main slab is made of a slightly smaller LECA, uncoated (presumably to allow better binding), mixed with NHL5 (Natural Hydraulic Lime). A breathable membrane is used both below and above the loose lay LECA to prevent migration between the layers. On top of the slab a screed of NHL5 and sharp sand is laid, on which the chosen floor surface is laid." I think the coating on the LECA was to make it more waterproof (when used in the base layer), and obviously you don't want it waterproof when mixing with NHL for the slab.

I recently did another smaller limecrete floor in my hall using Recycled Foamed Glass (RFG). This is actually tamped (with whacker plate) and so doesn't move when the mortar is laid on it. This was the reason I chose it, apart from the fact that Mike Wye do not seem to stock LECA any longer which was available in sensible bags (10 or 20kg) but that was a long time ago. I recommend RFG in place of LECA, but you might have the same issue with small quantities.

Matthew
See http://houseintheenchantedforest.blogspot.com/ and find entries in April 2011

[Kearn]

Depending on where you are, I have surplus RFG, 3 sacks from memory, due to having to buy more than I needed when I laid a limecrete floor. I tried to give it away in this forum a few years ago… free to a needy home.

It’s pretty easy to work with, for a very small area you may get away with just a lot of manual tamping instead of a whacker plate, depending on space and geometry you may get no choice anyway!