Solid wood flooring expansion

[NelsonR]

Hi, there,
I'm about to lay a floor using 90mm solid oak T&G with a lacquered finish.
It's in a loft bedroom, and is going onto nice, clean, level chipboard.
What I don't understand get is the need for 10-12mm of expansion gap all round.
I understand that the wood will expand/contract (mainly widthwise), but if the
planks are fixed with secret nailing how can the overall expansion be that large?
Surely the outer planks would be torn from their nails!
I'd be really grateful for an explanation...

 

[WoodYouLike]

Wood works, always. No matter how you install it.
Rule of thumb with Solid Oak floors: 3 - 4 mm expansion gap per meter width of the room, minimum 10mm total.

This doesn't mean that all planks will expand 3 - 4 mm individually, but planks over the width of 1 meter can expand 3 - 4 mm together. Not enough individually to lift out of the nails or 'break the bonding' with adhesive when you glue it down, but together enough to need that expansion gap.


BTW, it's never a good idea to nail on chipboard!

 

[NelsonR]

Hi, there, WoodYouLike!
That's a really quick reply, thanks!
I've had a good look at your website and it's loaded with
excellent advice: other posters would be well advised to look there
first.
I'm afraid I still don't get it, though. Suppose all the planks
are 100mm wide, and they each expand 0.3mm. If the whole
floor expands equally, a plank 2m away (i.e. 20 planks) from the middle
of the room has to move 20 x 0.3 = 6mm relative to its original position.
Whether it's nailed or glued down, surely something will tear?
Maybe it would be better to go with the floating method.

 

[WoodYouLike]

Trust me, it doesn't work that way. Every board will react differently to changes in humidity.
The nailing method, the glueing method and the floating method all account for this phenomenon, leaving an expansion gaps based on the rule of thumb will prevent big problems.

In your case floating would be a better option than nailing into chipboard. Use an underlayment for sound insulation that doesn't contain a dpm.

(And thanks for the compliment regards our website )
And as for quick reply, just happen to look at the DIY-not side when your question was published - pure chance)

 

[NelsonR]

OK, I give up
I still don't see how that works, but
I know when to take advice!
I'll go with the floating method, I think.
Many thanks for your valuable help.