Solid Wooden Floor Advice

Pete_Lee

Hi Everyone,

Longtime lurker, first time poster here. I'm looking for some advice on flooring in an old house that we have just bought. The structural engineer has pointed out that there is no DPM or insulation on the concrete slab. We plan to put down a solid wood floor so I was originally thinking of a DPM followed by a thin layer of insulation, a layer of plywood and then nailing the solid floor down.

The problem is in the height of the ceiling which sits just 2.2m above the floor. Ideally, we would like to avoid reducing this much and so I have changed tact. My current plan is to use a DPM followed by 40mm of Insulation and then an adhesive underlay eliminating the need for plywood. Would this work? Does an adhesive underlay form a strong enough bond to the wood?

Cheers

Pete

Rows Grower

While you have the chance now you should dig up the floor and do it properly, it'll be a bit messy but well worth it in the long run.

listermint

have to agree with above, dig it out. DPC, insulation and pour new floor surface.

Can get micro diggers now that will go into doorways takes out alot of the effort.(not all of it though)

The Continental Op

Traditionally solid wood floor would have been put down with hot tar so no need for a DPM. Can't imagine anyone doing that now (the wood wouldn't be thick enough to start with) but tanking the floor with a bitumastic sealer before putting down the DPM wouldn't go amiss.

Pete_Lee

Thanks folks,

My issue with digging out the floor is that there is already very little difference between outside and inside level so I actually won't be able to gain much either way. Also with an old house 120+ years, I'm more inclined to leave well enough alone incase the floor slab is what's holding it all together ����

In all honesty, it's mostly a budget issue. We need to make it comfortable and move in on a very tight budget so digging up the floors just isn't an option at the minute!

Pete

Lumen

DPM is supposed to go under the concrete slab not over. I think you'll have damp issues at the floor/wall junctions with this approach.

Pete_Lee

Lumen wrote: »

DPM is supposed to go under the concrete slab not over. I think you'll have damp issues at the floor/wall junctions with this approach.

Makes sense - So am I actually better off to leave a breathable covering over the concrete to allow any damp escape. There are no signs of any dampness on the concrete slab. It's been covered with underlay and carpet for years and no signs of any moisture when I removed them. Also no signs of any damp coming up the walls etc.

Pete

Rows Grower

Pete_Lee wrote: »

Thanks folks,

My issue with digging out the floor is that there is already very little difference between outside and inside level so I actually won't be able to gain much either way. Also with an old house 120+ years, I'm more inclined to leave well enough alone incase the floor slab is what's holding it all together ����

In all honesty, it's mostly a budget issue. We need to make it comfortable and move in on a very tight budget so digging up the floors just isn't an option at the minute!

Pete

A pick, a shovel and a wheelbarrow won't cost a whole lot. You'd buy a brand new kango in Aldi for under 200 euro.

Lumen

Pete_Lee wrote: »

Makes sense - So am I actually better off to leave a breathable covering over the concrete to allow any damp escape. There are no signs of any dampness on the concrete slab. It's been covered with underlay and carpet for years and no signs of any moisture when I removed them. Also no signs of any damp coming up the walls etc.

Pete

It's possible that the moisture has been breathing up through the carpet and underlay, and that when you trap the moisture with plastic it'll migrate to the edges.

There are some breathable products like Pavaboard (woodfibre) which might work. Calcium silicate boards are the ultimate in terms of hygroscopic and capillary performance but I don't think they're load bearing so only used in walls and ceilings.

What does the engineer recommend? I'm guessing "dig it out". :pac:

Lumen

Oh, the other thing to consider is floor levels. If you raise them, a bunch of things become problematic. Like stumbling at the bottom of the stairs because the rise is shortened.

Pete_Lee

Lumen wrote: »

It's possible that the moisture has been breathing up through the carpet and underlay, and that when you trap the moisture with plastic it'll migrate to the edges.

There are some breathable products like Pavaboard (woodfibre) which might work. Calcium silicate boards are the ultimate in terms of hygroscopic and capillary performance but I don't think they're load bearing so only used in walls and ceilings.

What does the engineer recommend? I'm guessing "dig it out". :pac:

Surpringly not - he recommended Wattstop Epoxy Cement Sealer followed by a layer of vacuum insulation and then whatever flooring we choose. I just want to replace the vacuum insulation as it's bloody expensive!

Pete

Pete_Lee

Lumen wrote: »

Oh, the other thing to consider is floor levels. If you raise them, a bunch of things become problematic. Like stumbling at the bottom of the stairs because the rise is shortened.

The stairs is in the front room which has old tiles down - we're leaving them in place for the minute so I'm not too worried about that at the moment. Eventually the stairs will have to be replaced anyway (it's only 650mm wide) so we'll do that all to fit properly once we are tackling that room.

Pete

The Continental Op

Pete_Lee wrote: »

Surpringly not - he recommended Wattstop Epoxy Cement Sealer followed by a layer of vacuum insulation and then whatever flooring we choose. I just want to replace the vacuum insulation as it's bloody expensive!

Pete

Bitumen was what was used before Epoxy.

Pete_Lee

The Continental Op wrote: »

Bitumen was what was used before Epoxy.

From what I've read on this (permagard.co.uk/advice/damp-proof-concrete-floors) quite helpful website - the epoxy/bitumen is the way to go as it doesn't allow the moisture to get all the way through the concrete and therefore it can't be pushed to the edges and up the walls.

In this case, I would be looking at a layer of Epoxy/Bitumen, followed by insulation and then the adhesive underlay to stick the floor down.

Or am I still better off putting in the layer of ply above the insulation?

Pete

Lumen

If the epoxy base is level I don't see any advantage to adding ply, except that it'll be easier to pull up in future if you're gluing the finished floor down.

Is it a plank floor or something fancy like parquet? Presumably the floor supplier can advise on suitable underlay.

Pete_Lee

Lumen wrote: »

If the epoxy base is level I don't see any advantage to adding ply, except that it'll be easier to pull up in future if you're gluing the finished floor down.

Is it a plank floor or something fancy like parquet? Presumably the floor supplier can advise on suitable underlay.

Downstairs is plank and upstairs is parquet. I was going to try both with the self adhesive underlay as it seems like an easier option for a novice like me!

Pete

The Continental Op

Have you tried taping a sheet of plastic down on the floor. Tape it all around then take it up a few days later and see what moisture if any has collected under the plastic. None is good lots is bad.

Why not stone floor downstairs. If its an old cottage work with it not against it. The floor will be cold but you don't have to use the foam.

Pete_Lee

The Continental Op wrote: »

Have you tried taping a sheet of plastic down on the floor. Tape it all around then take it up a few days later and see what moisture if any has collected under the plastic. None is good lots is bad.

That's exactly what I'll do. I'll be there tomorrow and won't be back until Sunday. It'll be a decent indicator if nothing else!

Pete