Hybrid floor / limecrete perimeter

[jonthefish]

We’re going to install a new floor with underfloor heating. We're considering limecrete but is a lot of work, quite costly and the drying time is substantial.

I’ve been reading about ‘hybrid floors’ – poured concrete with limecrete perimeter. Foamed glass insulation underneath does moisture control and most of the insulation, PIR under the concrete. I can see advantages. Speed of installation if we can have it poured and rapid curing time. And a platform to work from to do the limecrete perimeter ourselves.

My main worry would be differential expansion/contraction potentially leading to movement at the limecrete/concrete joints.

I've read varies opinions on these kinds of perimeters, but does anyone have any experience of doing its? Pros and cons? Or strong opinions.....
Thanks

 

[a twig]

A search on here for “limecrete” and “perimeter” will reveal a few that have done it to generally good effect.

If memory serves me correctly @elizabeth was one of the most recent

 

[Kearn]

We’re going to install a new floor with underfloor heating. We're considering limecrete but is a lot of work, quite costly and the drying time is substantial.

I’ve been reading about ‘hybrid floors’ – poured concrete with limecrete perimeter. Foamed glass insulation underneath does moisture control and most of the insulation, PIR under the concrete. I can see advantages. Speed of installation if we can have it poured and rapid curing time. And a platform to work from to do the limecrete perimeter ourselves.

My main worry would be differential expansion/contraction potentially leading to movement at the limecrete/concrete joints.

I've read varies opinions on these kinds of perimeters, but does anyone have any experience of doing its? Pros and cons? Or strong opinions.....
Thanks

View attachment 19558

Have a search and read through recent posts on the topic. What you’re proposing doesn’t make much sense.

Perimeters are sometimes well used, when an existing concrete floor is in place and people just deal with the perimeter to let moisture out through the limecrete slab, rather than driving it all to the walls. But this is thin limecrete onto soil…

Limecrete does not manage moisture in the RFG setup.
No moisture reaches the slab if the RFG is correctly installed. It’s a capillary break, think of it is a big fat DPM effectively. A minute, irrelevant .% of vapour may rise though the RFG, but this isn’t worth worrying about.

If you’re digging down and going to the effort of getting a decent depth of RFG in, this is your insulation already, as well as type 1 equivalent once whacked down and compressed.

You can then happily pour a cheaper concrete slab over the RFG.

The drying time of limecrete floors is also faster than an equivalent depth traditional concrete slab, if time is your concern.

Concrete will be in the region of 1day per mm of depth, so you can easily be waiting months.
Limecrete you can tile over after a couple of weeks, IF you don’t grout and leave the gaps open for some time to allow residual moisture out. I’ve done exactly that with one of my floors i needed tiles on fast…