laying a wood floor over concrete

[K.McBarron]

We are trying to restore our old house, the interior of which was completely modernised by previous owners. The ground floor has a concrete floor covered by a fitted carpet. As we are currently restoring the ground floor, we would like to get wooden floor boards laid and use loose oriental carpets over them to give a more traditional feel. Is it possible to do this without digging out the concrete? Do we have to put wood lats below the floorboards? Can these be glued?

Any advice or previous experience would be much appreciated! Keith & Martha

 

[Flyfisher]

Welcome to the forum (or asylum as it should probably be called).

I've installed a suspended wood floor over an existing concrete floor, but that involved a height increase of about five inches so it may not be the sort of thing you're thinking about.

You say the property has been modernised; do you know the construction of the concrete floor, as this may affect the best way to proceed, e.g. is there a proper, functioning DPC, is there adequate insulation beneath the slab? etc.

Our concrete floor was old and with no DPC that we knew of, so I wanted to add additional insulation and also ensure adequate airflow under the floor to avoid any damp issues, hence the overall height increase. Fortunately, the height was not an issue in our case.

I'm not sure about laying a wooden floorboards directly onto a concrete slab, but hopefully someone who does will be along soon.

 

[Penners]

Flyfisher has identified the important points that you need to consider. If you lay the floor directly on to concrete which has no DPM and no insulation, you risk a number of problems:-

1. The glue used to secure the floor to the concrete may fail.

2. Warm household air hitting the cold concrete could cause condensation. In the short term this could cause "cupping" of the boards (ie: curling upwards) and in the longer term you could risk rot in the wood.

Under these circumstances you should ideally "hang" flooring joists above the concrete floor, with an effective layer of insulation above an air-gap above the concrete (make sure the air-gap is ventilated with air bricks in the external walls). Then secure your floor to the joists. Obviously this technique depends on whether you have the headroom to do it.

However, if your concrete is completely dry, well insulated and has an effective DPM, then you may be OK gluing the boards directly to it.

 

[ljn]

wood floors on ground floors are not ideal for the reasons already pointed out.
If you don't have a DPM, I wouldn't put wood on it, but look at another solution such as stone, or just polish the concrete.

If you do have a DPM/insulation, there are some excellent primer/glues for gluing wood to concrete.

Basin two-part primer (0200A and 0200B) is designed to prepare concrete with moisture content up to 4% for adhesives. You apply a coat of primer which penetrates the concrete and sprinkle with quarts sand, then apply another coat of primer. Basin also do excellent parquet glue. - I cant find a link as Googl thinks I'm looking for a bathroom sink.
You could try asking a specialist wood floor supplier such as http://www.naturalwoodfloor.co.uk/products.php?catID=3
They stock Lecol which is another good company for wood glues which may do a similar product to Basin.
Carver also do similar products.