Building the floor, will this work?

[Anne]

Hi Everyone,

I had great plans of putting down a limecrete floor and putting back the old flagstones that were previously turfed outside, but having now lifted up the concrete we've found that the entire floor base is limestone bedrock, it's not flat but not to far off it either however the few creaters in it and its jagged edges mean I need a floor over it if I want to cook without breaking my neck.

The problem is that I only have 4 to 5 inches from the bedrock to where the floor needs to be. I don't want to raise the level as that is not how the room was intended, and I'm limited by the lintel height which the Aga will sit under. The advice I've recieved was to simply put down a layer of Geotex and then a layer of limecrete and bed my flagstones into that while it's wet. I was warned however that it may not stop the damp. Being as there was a concrete floor there for 40 years and it wasn't breathing the bedrock really isn't to bad. What we found was damp but not overly so. So I'm looking for opinions. Is this going to work, anything else I should think about?

 

[Tom]

A Limecrete floor isn't intended to stop the damp so whoever told you that doesn't understand how a Limecrete floor should work.

Speak to Ty Mawr Lime and tell them what you've got. They worked out everything we needed for our Limecrete floor and it's worked out brilliantly. Good luck!

Jaqy

 

[Gervase]

Ideally your slab wants to be four inches thick to have the necessary strength to withstand day-to-day use without cracking.
In your position I'd be tempted to blind the stone with sharp sand to get a level (and use just the minimum amount of sand, no thicker), then put down a layer of geotex and then pour on the limecrete to a three-inch thickness, allow ten days for a strong enough set to walk on and then pour on a bedding base for your slabs of a much thicker consistency and made with finer aggregate. all of which should just about keep you indside the desired height. Just.
It's not something I've had to do, however, so do check with Tom at Ty Mawr (01874 658000). And don't tell the building inspector, as it will not conform to Part L without the expanded aggregate insulating base!