Screw spacing for plywood overboarding

[Tim Lamb]

I have now reached to point of laying 12mm plywood over the underfloor heating grooved chipboard.

Any suggestions for suitable screw spacing?

[Iggy]

replying to Tim Lamb, Iggy wrote: For everything but tile, every 150mm at the board edges and every 300mm in the board field. This will and should match the subfloor's screw spacing. For tiled areas every 75mm at the board edges and every 150mm in the board field.

[Tim Lamb]

OK Iggy. Now all I have to do is avoid the pipes:-(

[Rob Graham]

Many years ago now I went to a Murrayfield rugby match with a friend's wife while he replaced the wire nails the plumber had used with lost heads so t hat the floor could be polished. We returned some hours later to find his b rother crouching on the floor with his fingers over as many holes as possib le while the husband had gone off to find the plumber to turn off the water !!

[Andrew]

?None. Can you not glue the overlay onto the chipboard ?.

Why are the heating pipes in grooved chipboard ?. Don't people normally use grooved insulation material with metal spreaders to transfer the heat ?.

Is there a photo ?

[Tim Lamb]

No:-)

There is a 3mm foam underlay and the pipes have aluminium spreader plates.

There are lots of ways to do this. I have to use an overboard set up because the builders used random joist spacing.

I'm taking shots as records.

[Tim Lamb]

Ha ha:-(

No water in mine yet but I will test with compressed air.

[John Rumm]

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.

[Tim Lamb]

I'm going with Iggy's 6" on the periphery but the pipe spacing is not a convenient 12" so the rest tend to be a bit random. Very stressful activity:-(

Full marks to Toolstation. 6 packs of screws ordered Sunday evening. Arrived 8.30am! today.

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