Limecrete floor and floorboards

[FCC]

Hello,
We've a stone cottage built into a hill so inside on one side the internal ground level is ~1m lower than external ground level. There's no dpc.

We had thought about putting a limecrete floor in but were wanting a wooden finish as bit warmer than stone (not having UFH). I have read that need to put battens down and attach floorboards to them. One of the companies we contacted said to go with the glass insulation but to forgo the limecrete slab and just make a floating wooden floor on top (using 2 by 4 battens) upon which we can put floorboards.

The original floor was cobbles upon which battens had been laid (touching cobbles) and not surprisingly we had woodworm.

Does this floating floor seem like a bad idea? I am concerned about rot. Do floorboards seem like a bad idea and should we just go for stone slabs? I've been going round in circles so any thoughts/advice would be appreciated!

Thanks

 

[CarolineTheChemist]

I’m a bit confused on how the glass foam would work with the suspended floor. Will you also have pillars for the floor joists to sit on and then fill in the void in between the pillars with the glass foam and then compact it? How high up would you fill with the glass foam? What about air bricks and ventilation?

Perhaps the plan is to forgo any ventilation and fill the entire area with the glass foam nuggets?
If so, I can see future problems. The glass foam doesn’t stop moisture rising from the ground. The amount of moisture that rises through the foam will depend on how far down you excavate before filling, but it’s not an impermeable barrier so you’d still need to ventilate the area around the wood floor to stop it getting damp.

So if you’re ventilating beneath the wooden floor with fresh air, there’s probably not that much point to the glass foam insulation. It’s not cheap!

 

[FCC]

I probably didn't explain it too well. The floor wouldn't be a suspended one, just battens onto the foam glass with floorboards on top. I am a bit sceptical as also concerned re moisture but then I have read on various lime companies' websites that can use floorboards as a finish on top of limecrete floors provided battens are used. So in effect, is the above not exactly the same as going for limecrete flooring + floorboards just minus the limecrete slab?

Should floorboards just be a no for limecrete floors? I am more tempted for foam glass + limecrete + tiles of some sort but my other half wants floorboards!

 

[CarolineTheChemist]

I’m still confused about how you’d batten onto the glass foam. We had a limecrete floor installed a few months ago and although the glass foam was compacted a lot, the foam nuggets were still uneven and somewhat loose on the top. It certainly didn’t feel like a sensible substrate to attach a floor to…. Perhaps I’m misunderstanding how it’d work.

With regards to wooden finishes on a limecrete-like set up, I guess it would depend on how breathable the wooden finish is (avoid tight fitting engineered wood) and long you’d like the floor to last. Personally I think you’d be asking for trouble if you attached floorboards directly to the glass foam as moisture still rises through it and the wood will get damp, even if there are big draughty gaps between the floorboards. I suspect wooden floorboards on top of a limecrete screed would last longer, but it seems like a big effort and expense when a well ventilated suspended timber floor could last just as long.

 

[FCC]

Thanks for your thoughts, much appreciated. Yep, it does sound tricky fixing to foam glass, I think more research is in order! I just wanted to hear people's thoughts as offered as an option by limecrete company.

A suspended timber floor isn't an option due to the building - simply can't dig deep enough and even if we could, there's no way of providing adequate ventilation.
I think limecrete + tiles is the best option...

 

[CarolineTheChemist]

I’m inclined to agree that limecrete might be your best option. It’s hard to know without really seeing what you’re dealing with. We also had a similar discussion when trying to decide on a finish for our floor. We also would have liked wood too, but have settled (for now) on tiles and breathable carpet.

I’ve attached a few snaps of our limecrete installation in case they’re of interest. We had The Limecrete Company come all the way from Norfolk do our screed, but we got our regular builders to do all the prep for it.

I hope it’s helpful or a least a bit interesting. We originally planned to put UFH in the round room, but changed our minds last minute. We’re currently in the process of putting down another limecrete floor in the main house with the lessons we learnt from the first one!

 

[FCC]

Thanks so much for posting those pictures, very useful and interesting. You have a lovely house! I like the one with your dog, ours has been very keen to get involved with the diy!

 

[jamest]

The approach I've taken is to float engineered oak boards over a hard subfloor (concrete with no dpm - not limecrete, but moisture still gets through it) and use the kind of dpm membrane under the floor boards that allows water vapour to migrate out at the edges of the floor. Such membranes were developed to allow the installation of wood and laminate floors over a subfloor that has not fully cured - the one I used was Newton slimline, it's about 2 to 2.5 mm thick and firm (i.e., not a plastic sheet) with grooves in it that allow the migration of vapour. It seems to be fine, but to be fair, I haven't lifted the floorboards to see how things are going beneath. You need to make sure the edges aren't sealed as well - no caulking of the skirting or grilles in the skirting.

I don't know whether this 'solution' would count as best practice, but as far as I can tell, it works in the sense that I don't have damp edges to the floors or skirtings and everything else seems fine. The previous owner had carpets down and the edges of the carpet were damp and the skirting (which was sealed along the top edge) was mouldy on the back - I no longer have any such problems or any sign thereof!