To board or not to board - that is the question.

[TimM]

Having tiled my bathroom - onto chipboard - and boarded it out with ply first I am now looking to do my hall. We are looking for a cottage feel and so are using natural slate. It is about 8 metres in length with several twists and turns. I have decided that on this job I need a professional to ensure it is done right. The tiles will in the main be fixed to solid floorboards that are t&g, they are mostly in very good condition and have been down for some time. There is a small area of concrete screed. So far I have been told it needs overboarding with ply ( of varying thicknesses) , backer board 6mm depth and that neither is needed, using bal quickflex instead. I must admit being tempted by the quickflex option as it means less impact on height and also when you add in the costs of boarding (both material and time) it starts to look very tempting. Having had the fact that you always have to board out wooden floors beaten into me, I am hesitant about taking this route.

Any thoughts or advice please?

[faithhealer]

board it 100%
welcome to the forum

[kkoll]

Pardon the pun, but welcome on board! And yes I would also say board it, screwed at 300mm centres minimum and at least 15mm ply to ensure rigidity.

[doug boardley]

definitely overboard your T & G, make sure they are firmly screwed to joists first and that there is no deflection, ie "bounce" I'd overboard with hardibacker 250 for minimal height impact.

[TimM]

Thanks so far chaps. 2 for ply and one hardibacker.

I am a tall guy so the height issue is relevant - I already have to duck on several doors so the lower the solution the better.

No one seems keen on the quickflex option.

Nice taste in music Doug, although a little dark!

[aph257]

I'd use No More Ply

[doug boardley]

[QUOTE=TimM;401867]Thanks so far chaps. 2 for ply and one hardibacker.

I am a tall guy so the height issue is relevant - I already have to duck on several doors so the lower the solution the better.

No one seems keen on the quickflex option.

Nice taste in music Doug, although a little dark![/QUOTE]

lol, I didn't even post my goth stuff in my profile

[Dave]

Your over boarding is governed by the deflection in the sub-floor..

The more solid it is before hand ,then you can go the hardibacker 250 route..

[Ken Bruty]

woohoo!! fame at last Doug

[doug boardley]

Your over boarding is governed by t he deflection i n the sub-floor..

The more solid it is before hand ,then you can go the hardibacker 250 rote..

but hardie is no good for insulation is it, bearing in mind that Tim wants to have ufh

[Dave]

Not gunna loose a lot of heat on timber floors Doug..

[doug boardley]

Not gunna loose a lot of heat on timber floors Doug..

[doug boardley]

woohoo!! fame at last Doug

if only for my taste in music

[Phil Hobson]

Over board every time for me, any product that promotes' tiling directly onto t&g, is imo very bad

[doug boardley]

Your over boarding is governed by the deflection in the sub-floor..

The more solid it is before hand ,then you can go the hardibacker 250 route..

if you aim for zero deflection tho' Dave, (as you should), then surely an insulation board would be a better option in this case than hardie, especially as you can get ekoboard in 6mm thickness.

[TimM]

chaps,
Thanks for your time and thoughts, really interesting and giving me lots to think about- I never realised tiling could be so geeky! Which for me is a good thing. However not quite sure if I can see a difference between hardi and No More Ply
As further information:
No underfloor heating is required.
T&G floorboards are solid - well one squeaks a bit, I will be Going over them and screwing down anything a bit loose anyway. I think I am correct in saying that deflection is the amount the floor boards move and by over boarding you are looking to reduce this to the lowest level poss. In which case it is already minimal.

As the t&g have been down for about 20/25 years there is little moisture left in them, but there is about a 2ft void under them.

[Dave]

if you aim for zero deflection tho' Dave, (as you should), then surely an insulation board would be a better option in this case than hardie, especially as you can get ekoboard in 6mm thickness.

Insulation boards are no where near as sturdy as hardi..but if insulation is required then they can be used if deflection is at a minimum..

[doug boardley]

I've actually got this mixed up with another thread (patl's), my sincere apologies,

[TimM]

Too much Interpol.

[faithhealer]

I've actually got this mixed up with another thread (patl's), my sincere apologies,

lol you need a(another) holiday Dougie

[doug boardley]

lol you need a(another) holiday Dougie

14,000 plus posts, I think I'm allowed to slip now and again John (unlike Dave, who always has his eye on the ball)

[Daz]

However not quite sure if I can see a difference between hardi and No More Ply

In my experience, I have found NMP to be more solid than Hardie 250. If there is the slightest amount of deflection then I choose NMP in favour of Hardie 250. Hardie seems to be lower cost but NMP will add a small amount of rigidity to a floor IMO.

[TimM]

Thanks to everyone for their contributions so far. I was tempted by the non-boarding option, but that looks to have disappeared to the long grass with no one expressing a positive view. Now I have to decide the level to which I have to duck going through doors!

[Daz]

If height really is an issue, then take up the floorboards, add extra noggins to the joists and then fix 18mm wbp ply. Remember to prime the underside and edges before fixing. Screw the boards down and max 300mm centres and you should achieve a good deflection free floor. Depending on what tiles you are installing, you can fix directly to the ply. That'll save you 6mm .

[TimM]

Clever reply Captain, hadnt thought about that.

[boldydave]

To captain slow

If height really is an issue, then take up the floorboards, add extra noggins to the joists and then fix 18mm wbp ply. Remember to prime the underside and edges before fixing. Screw the boards down and max 300mm centres and you should achieve a good deflection free floor. Depending on what tiles you are installing, you can fix directly to the ply. That'll save you 6mm .
__________________

i`m not a pro tiler and was interested in why you seal the underside of the board?thanks, dave.

[Daz]

You prime the sides and underside of the ply to assist in the prevention of moisture ingress. You may need to prime the face of the ply too, depending on adhesive manufacturers instructions.