Tiling on wooden floor expriencing movement

[AndyS]

Part of the area I wish to have tiled experiences some "bounce" in the floor. I would imagine that floor movement would not be good for the life of tiles so I am wondering what my options are to resolving this.
Other info;

- Our house is around 50 years old, double brick.
- There is access under the house although it would be reasonably cramped. It used to be the back verandah area.
- Only this area of the house appears to have a significant issue. The house sits on sandstone and has brick piers.

A

[Bleedin Thumb]

Not good. FC sheeting underlay will be requied.

Posted by a fool who didn't use it.:doh:

[AndyS]

Not good. FC sheeting underlay will be requied.

Posted by a fool who didn't use it.:doh:

Oh dear, to avoid that experience :) could you or someone clarify the implications of FC sheeting underlay? Ie presumably the sheeting would provide more rigidity but how thick would it need to be?
Also I would imagine that there is a limit to how much bounce can be eliminated before more serious work is required. I am not saying we have a trampoline but I would hate to go to work only to find the solution insufficient. How would you begin to determine whether you have too much bounce? My 'gut' is telling me that the answer is probably down to experience and how paranoid you are but if there are some thoughts out there I would be interested to know.

Ta muchly

A

[myla]

hello,

treat the bounce as seperate issue to doing the tiling

you can get tile underlay from bunnies etc, i think normally around 4 or 6mm, would say this will do nothing about bounce, cement sheet underlay is nailed down with lots of nails (no glue)

with the bounce you need to get under the house and see whats happening

the span may be too big, you may be able to put "stiffer" joist next to existing ones to stop or reduce bounce

thankyou

myla

[bitingmidge]

Andy,

If you have ANY bounce, you WILL get cracks.

Assuming a VERY rigid structure, you'll get away with a tile underlay, but that's not what you have here!

You can reduce the deflection in bearers by bunging in a post mid-span.

You can reduce the deflection in floor joists by bunging in a bearer mid-span.

The only way you can reduce the deflection in floor boards is by replacing them with something thicker!

In the good old days, we used to build a small suspended concrete floor in the wet areas to tile (or pour terazzo over). Then along came this magic stuff called Compressed Asbestos (now fibre) cement and we used to use 18 mm thick sheets that three grown could barely carry.

Then some bright spark realised that you could probably get away with a bit of plastic over the ply floor, lay a tile bed, and she'll be right.

So: Reduce the deflection in the structure as much as you can. Consider replacing the floor boards with CFC but remember you WILL get cracking in the tiles over the joints if you haven't got the bounce out of the structure.

Or think about how nice the floor will look in polished timber! :wink: After all, that's what the structure is best suited to.

Cheers,

P

[mic-d]

I agree with what Midge says, resolve the bounce by looking at the underlying structure. When you have solved that, then lay 6mm tile underlay over the timber before tiling.

Midge, I still do mortar beds in wet areas - I'm such a ludite ;)

Cheers
Michael

[bitingmidge]

But you don't get cracks across the joints do you! :wink:

P

[pawnhead]

Agreed, you have to get the bounce out if you're going to tile.
Then along came this magic stuff called Compressed Asbestos (now fibre) cement and we used to use 18 mm thick sheets that three grown could barely carry.Scyon (http://www.jameshardie.com.au/Products/Flooring/ScyonInteriorWetAreaFlooring/) is a fair bit lighter, and you can nail it down instead of drilling and screwing.

[bitingmidge]

Thanks John, I must get myself into the 21st century! :- (watch the joist spacing though, in the old verandah it may be more than 450 which is what it needs to be for Scyon.

I reckon there'll be a bit of rebuilding happening here!

Cheers,

P
:D

[billbeee]

Andy,
Midge spot on about stiffening up the floor.
If you go the way of lifting the flooring, then access to stiffen it up will be a lot easier.

I had a kitchen in a high set house, that had 125 x 50 HW joists at 450 ctrs. spanning about 3300.
That sprung a bit, I should have used 150's. (first house, strapped for cash)
The flooring was pre-loved form ply.

I put in about 3 rows of noggins to stiffen the joists. Noggins, herringbone bracing, call em what you want will stiffen up any floor.

I nailed 6mm hardiflex to the ply and I used a rubberised tile adhesive.
The floor was still perfect after twenty years when we sold the place.

Cheers
Bill

[AndyS]

Thankyou for all the responses and advice. Plenty to go on with :) .

Andrew