UKC

Hi folks.

I am wanting to put down some solid hardwood flooring onto an existing concrete floor and I was wondering if I need a wood underlay as well as the damp proof membrane? A shop told me I need to purchase a under-wood which costs nearly as much as the flooring but the main problem is that it is raising the floor by another inch making it quite a bit higher than the ajoining rooms.

In reply to Milesy: How are you going to fasten it down?

I think some solid types have a tounge and groove so I would just slot them all together leaving an expansion area at the walls?

In reply to Milesy:

I've just had a solid wood floating floor laid on concrete. Just thin foam underlay and DPM underneath it. Seems fine. I've not heard of another layer of wood in those circumstances, though presumably it will make it a bit more stable.

In reply to Milesy: We've just laid approx 65m2 of oak flooring. That doesn't make me god or anything and I could be wrong but I think NOBODY recommends having a floating floor for hardwood. A floating floor is simply where the floor is laid but not fixed. The tongue and groove makes no difference.

Over time it is possible and likely that you will get movement due to seasonal changes in moisture levels and / or variance between moisture content of wood and that of your house. This movement can result in bowing, contraction, bending etc. Fixing reduces potential for this.

If laying direct onto a concrete slab the slab should be thoroughly dried first - something like a month's drying time per inch of slab (obviously if the solid floor has been down forever this is irrelevant). Damp proof membrane is then laid. I GUESS you can then just fix through flooring into slab, using suitable fixings. Standard practice (I think!) is however to lay softwood battens and then fix (using secret nailer through tongue) the floor into these.

I don't know why you don't just lay straight onto slab, perhaps it's to do with ensuring any height differences and irregularities are taken out / diminished.

I suggest a bit more homework before you start laying...

In reply to Milesy: It may specify it for fixing more so at an inch thick I assume it's for a hidden nailer. At work they always tend to lay a dpm on the concrete then fix ply and then the flooring is fixed to that. No idea on the prices but I would hazard a guess that ply is cheaper then special under flooring!

In reply to Milesy: Hi, I work for a hardwood flooring company so know a bit about this but I will stress Im not a fitter so dont take this as gospel!

Basically, fix it down. If you dont you're just going to end up with problems a few years down the line. If you dont want the added thickness of ply on top of the concrete thats fine, just glue it down instead. As long as you have your DPM down (two coats) then you can glue straight to this with a flexible adhesive that allows the flooring to expand and contract with changes in temp. As for which adhesive thats a minefield as a lot depends on how level your sub-floor is as well as the width of the boards you are laying. Here is a link to our website which has loads of info on the matter and will hopefully tell you all you need to know...www.euroak.co.uk

If you want any advice just give us a ring or an email and the guys at work will be sure to point you in the right direction.

In reply to Milesy: The way to lay solid t&g flooring is secret nail onto joists/battens with a dpm wherever the battens or joists touch concrete.

In reply to dan: thats certainly A way, but definitely not THE way and if the op doesnt want to raise the floor anymore probably not applicable here...just saying

In reply to Milesy:

Have you considered engineered wood flooring? Not the cheap laminated type with fake plastic wood pattern but ones with a thin layer of real hardwood laminated on top of composite planks. They will not take as many sanding as solid hardwood floor but do provide a real wood finish. The patterns tend to be more regular than solid wood but far better than the fake plastic stuff. This is an example:

http://en.parador.eu/products-catalogue/engineered-wood-flooring

Normally they are about 13-16mm thick rather than 20-25mm (as solid wood flooring). The tongue and groove of engineered flooring is interlocking so you don't need to use nails. They are suitable to be laid as a floating floor.

If your current concrete floor is too uneven you can put a thin layer of self-leveling screed over. This will make things a lot easier whether you go for a batten and nail option (for solid wood) or floating floor.

In reply to Milesy: Hmm we've had wood floors on concrete in our last 3 houses. Never heard of "underwood"? (well apart from the England rugby player.)

First place was engineered wood laid as a floating floor over a sound deadening fibre layer.. worked fine and looked great for the 3 years we were there. But only very small rooms. Second place was half inch French oak board, was nailed onto a chipboard type base. Beautiful floor across large rooms.
Current place is.... concrete then 2 X 50mm polystyrene sheet, then damp proof layer, then 12.5 mm chipboard sheet, then 6 mm plywood then nailed down 12.5 mm pressed bamboo top layer. (ok it's not wood but close enough). If it all turned to mush we'd be up to our knees in it.

In reply to jsmith1710: You are quite correct mate, but I was giving"professional" advice as a joiner.

Thanks everyone. We have researched far and wide and ready to start. We are going to lay plastic sheeting, and then thin DPM and then glue the lot. Nice walnut wood

In reply to ksjs:
>I think you can hire the nailers, doing it by hand & eye is hard work, and you can very easily damage the wood with the hammer.

In reply to Jim C:

I fitted a solid English oak floor in my lounge and hall.
The concrete floor has a damp proof membrane underneath so i just fully bonded it directly to the concrete with this stuff.

http://www.cityfloors.co.uk/ms-polymer-16kg.html

fantastic stuff but really messy if your not careful.
get the proper notched spreading tool they sell to match. it makes it a lot easier.

Andy