On 18/11/2017 20:25, Tim Lamb wrote:
I have now reached to point of laying 12mm plywood over the underfloor
heating grooved chipboard.

Any suggestions for suitable screw spacing?

If everything is basically flat, then I find 12" is normally ok. If if
its a bit more wafty, then come down to a smaller grid.

--
Cheers,

John.

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