Solid Oak Flooring - nail straight to joists ?

12 Jan 2009
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United Kingdom
I am about to embark on laying an oak floor in my house. This will be partly on a concrete sub-floor and partly on joists.

Regarding the joist areas, I really wanted to remove the existing floor in the two rooms (nailed pine boards in one room and chipboard in the other) and then secret nail the oak floor directly to the floor boards. Unfortunately, the manufacturer states that this can only be one where maximum distance between centres (?) is 300mm, whereas my joists appear to be approx 380mm apart judging by the nails in the existing floor. The solid oak I want to lay is 140mm wide and 20mm thick. Height is a bit of a premium in the rooms, hence wanting to remove the existing boards and so I have a dilemma. I am considering laying thin plywood (say 9mm) and then nail through the ply into the joists. Is this a good idea ? Are there alternatives ?

Also, is the use of DPM necessary with or without the plywood ?

Many thanks for any help

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Normally the heart-to-heart distance between joists should be maximum 350 - 400mm (35 - 40cm).
The 38cm is that the space between joists or hear-to-heart?
9mm plywood will hardly add anything to the load-bearing capacity, perhaps you're better of nailing strips of wood to the joists first to reduce the 'open space' between them?

Never use DPM when you are working with plywood and/or onto joists!
Thanks for the advice.

Infact - the distances are measured from the nails in the existing floor, so I guess this is heart to heart rather than space between.

Thinking about this - the weakpoints will be where the ends meet, and so I could add support in these areas only as a compromise - such as using noggins or just flat 18mm strips between the joists in these areas but flush to the joists.

If using no ply underneath, would you advise some sort of insulation ?

Thanks again


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