Solid beech flooring over very large concrete floor

[Andrew Haughton]

We hope to lay ex sports hall tongue and groove solid beech floor onto a concrete substrate. It is a huge space in an old warehouse with few straight lines but basically a level base. The total area to cover is about 250m2. My concern is how to lay them. Do we put down a dpm even though the floor seems dry year round? Do we use adhesive to bond the boards to the floor or is it better to glue the boards to each other and let the floor float?Should we strap the floor with 2" x 1" or worse still, 2" x 2" timber and nail the boards to that?
Any tips gratefully received.

 

[WoodYouLike]

What's the width of the boards? Sport halls normally had/have narrow boards so I think - if that's the case - it is best to fully bond them to your underfloor using flexible adhesive.

 

[Andrew Haughton]

Thanks for your reply. The boards were lifted from the demo site today!
They are close to 115mm x 25mm thick, tongue + groove including ends, lengths around 2.7m but a percentage of them are shorter and some boards have ends cut on lifting. It is very wet and needs to be dried (we are proposing to store it with sticks in between). It looks like Junckers floor boards I once used about 30 years ago though possibly thicker. - the boards are made from several strips bonded together. It was laid on 2 x 2 strapping. If you have further comments I would be immensly grateful as I fear it could be a disaster if we start this wrongly.
I'm aware we would still have to sand and finish the whole floor aswell. Perhaps it would be a bridge too far.

 

[mattysupra]

Is this warehouse heated and sealed? I.e windows doors etc that are to the quality of your house? What are you using it for? And when you say the wood is very wet, What is the reason for this and how have you tested it? You will have to do a moister test of the concrete base also as it may be wet, even tho it might look dry.

 

[Symptoms]

Andrew - a couple of observations:
wet boards - even with careful drying you may get 'cupping' across the width of all the boards even if carefully stacked. This can be addressed by planing the boards when flat(ish) after drying & before re-installation; as you've got a lot to do buy a half-decent planing machine for the task (sell it afterwards). If you don't do this you'll have great difficulty being able to get the finshed floor flat with a floor sander. Pre-planing then finish sanding is the approach to take. Also your reference to "ends cut on lifting" - don't waste these lengths, just re-cut the tongue & grooves on a router table.

How to fix? Well there was a clue in the original posting: "It was laid on 2 x 2 strapping". Presumably secret nailed. I've posted here before (do some searching via the Search in the Menu bar above) about reclaimed flooring (maple) over concrete, and I'm firmly in the batten (your "strapping") camp, although this should only be considered if you can accommodate an increase (25mm) in the finished floor height. Fix 25mm x 50mm treated timber (tile bats) to the concrete using a Hilty nailer, then secret nail your boards to these bats. Also, with such a large floor area, this method of installation would be the most efficient (quicker).

If you wish to take this approach and want more info then post again.