Overboard T&G floorboards with 12mm Ply or 6mm Hardie Backer Board

22 Nov 2016
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United Kingdom

ive overboarded t&g floorboards with 12m wbp ply before, however ive never used 6mm hardie backer board.

I was going to use 6mm hardie backer board this time.
18mm T&G existing floorboards.
glue the HB down with rapid set flexi powdered adhesive and screw down with 25mm stainless steel screws every 150mm.

is this just as good as using ply?
is this better than using ply?

is there any reason that either ply is better to use than hardie, or hardie is better to use than ply?

Cost wise, if i just use the Trade Point B&Q price for the ply, and tile supplier for the Hardi this is how much its going to cost.

Bathroom 2300 x 2050

12mm External Ply: 2x £21 = £42
Screws £2.50
Total = £44.50

Hardie: 6 x £9.6 = £57.60
Flexi rapid set tile adhesive 1x £12.50
Stainless steel screws £8.50
Fibre tape £5
Total = £83.60

Labour is more for the Hardie too.
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Hi @jasonss2016 Ply and tiles are not natural bed fellows, i would always point the clients into over boarding with a rigid backer board like Hardie or No More Ply.

I will add NMP to your price comparisons. The sheets are 600x1200x6mm so you would need 7 boards.

NMP is fixed using a special adhesive called Mega Strength, 2 rings of this below board, fixed to floor.

7 x NMP boards 7x£7.64 =£53.55
2 x 310ml Mega Adhesive @£6.09 = £12.19
1 x NMP box of 25mm screws =£5.92
Total £71.66

Ditra/Durabase matting is lighter, thinner, easier and healthier to cut, doesn't need screws, just flexi adhesive.. £6 a metre it's cheaper than nmp too and should lay faster

If you're considering underfloor heating wires, look at marmox style boards too.. available on eBay at 70quid for ten 10mm ones
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I didnt think ditra/durabase could be used for that for strengthening the floor?
I thought it was only a crack isolation membrane for going onto new screeds and across two different sub floor types etc?
Can it be usen on floorboards instead of ply or backer boards?

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