Deflection issue with No More Ply down

[Deleted member 46792]

Hello

I am a DIYer and after a successful shower tile project set about tiling bathroom floor. Victorian terraced house, previous floor - exposed original floorboards. After research and consultation with a carpenter, I understood that the deflection wasn't bad and that I should screw down any loose-ish floorboards and overboard with 6mm No More Ply using the NPM mega strength adhesive. Having done this and having been pretty pleased with my efforts I asked a tiler (and paid for consultation services) round to give me his opinion. He said that my floor has too much deflection and that the grout and possibly the tiles will crack. He gave me a couple of suggestions - the most expensive being to start again and lay down 18mm ply. This could be tricky as I understand that even in the event of a nuclear war the NMP will probably still be sticking to the floorboards because of the strength of the adhesive. The other option he said was to get some expensive adhesive - bal single part fastflex I think it was - which has an elastic ingredient and get flexible grout that you can add an additive to that will make the grout very flexible.
This evening I have been wondering if it isnt possible to double up with overboarding with a layer of ply or another layer of NMP. I also did a test that I have read about which involves filling a glass of water and placing in centre of room and getting biggest person you know to jump about a bit. Well I fit that profile so I have done that and no water was spilt. I can see some deflection in the floor but I am not sure what to think now. I am not sure what is acceptable, what remedial actions to take..

Anyone got any thoughts on this? I dont want to do a cr*p job but I dont want to pull the house down!

 

[Kevbos]

Lol contraversial kev

They said they were not going to rip up the original 6mm .ply .I was trying to solve it from there

 

[Andy Allen]

Depending how much your floor is bouncing.....and less face it non of us has seen it so can't really give an opinion on that.....however you say you have had a tiler round to have a look . So all I can say is using bal single part fast flex and bal wide joint grout with GT1 add mix would certainly allow for some movement and as your using a porcelain floor tiles and not some cheap bct rubbish then you might get away with it ....just remember to use a solid bed..minimum 10 mm trowel and back skim the tile.......

 

[Stef]

So I really have three options: 1) The correct way - rip up the NPM which will probably also destroy the floorboards. Fix/strengthen the joists so no deflection and lay 12/18mm ply floor, overboard with NPM or Hardiebacker. Tile. Expensive, disruptive and will make me cry.
2) The risky adhesive option - bearing in mind that the deflection is minimal a very flexible adhesive might resolve the problem. Only time will tell. 2 or 3 tiles would be affected. One commenter suggests he doesn't think i have a deflection problem in such a small room.
3) The raised floor option - Ply or hardiebacker. Adds 2 cm to the height of the floor. Will it definitely stop bounce after all that effort?

I hope the answer comes to me in the morning...night all. Thanks for weighing in.

Do you have a self levelling laser?
If you do then sit it in the middle of the room & mark it on the wall, stand beside it & get someone to mark the wall again & that will show you exactly how much movement you have in your floor.
I think you may be over thinking this floor too much as you always do get slight movement in a floor, it's trying to assess how much movement you do have, it's all well & good us sitting here trying to offer advise but we can't see the floor so it's a bit of a guessing game.

 

[Dan]

Depending how much your floor is bouncing.....and less face it non of us has seen it so can't really give an opinion on that.....however you say you have had a tiler round to have a look . So all I can say is using bal single part fast flex and bal wide joint grout with GT1 add mix would certainly allow for some movement and as your using a porcelain floor tiles and not some cheap bct rubbish then you might get away with it ....just remember to use a solid bed..minimum 10 mm trowel and back skim the tile.......

You won't need to back skim with fast flex I don't think. Unless things have changed as I think it's one part now isn't it?

 

[Andy Allen]

You won't need to back skim with fast flex I don't think. Unless things have changed as I think it's one part now isn't it?

It is one part now Dan but as with all porcelain tiles back skim to achieve a strong bond.

 

[Dan]

Ahh okay. Thought it was squishy enough. Used to need the fast flex trowel with ribs on the end to ensure a flat bed before even sticking to it.

Do you still need that expensive trowel you only used once in a blue moon?

 

[Andy Allen]

Ahh okay. Thought it was squishy enough. Used to need the fast flex trowel with ribs on the end to ensure a flat bed before even sticking to it.

Do you still need that expensive trowel you only used once in a blue moon?

Not really....I use fast flex a lot on wooden substrate. I just use 10mm notch trowel and back skim the tile. as long as you achieve full coverage that's the main issue.

 

[Dan]

Could you still tile your curtains with it if you wanted to now it's single part? I used to need to throw away my work trousers every bloody time it went near it let alone used it lol

 

[Andy Allen]

Could you still tile your curtains with it if you wanted to now it's single part? I used to need to throw away my work trousers every bloody time it went near it let alone used

Not as bad.....but still gets everwhere and a nightmare to remove....gloves are a must.

 

[Flintstone]

The stuff is horrible to use, I haven't needed it for ages than god.

 

[Deleted member 46792]

Video of deflection.

 

[Andy Allen]

Don't look like you have enough screws in it..

 

[widler]

To be honest all I can think about is you, stood there naked with your penis bouncing up and down and you laughing your head off

 

[widler]

Ps I'm happily married

 

[widler]

Erm, to a woman

 

[widler]

Yes, it's needs either more screws of ripping up and re doing

 

[Deleted member 46792]

To be honest there hasnt been much laughing in that bathroom the last couple of days...let alone any 'Elvis Willy'.

If put down a few more screws and it seems a bit better. I would consider ripping it up and starting again but from what ive read NMP + NMP megastrength adhesive is not something that is going to come apart from the underlying floorboards...

 

[Andy Allen]

Go to screwfix get some 20mm turbo gold screws fix them every 300mm using an impact driver and see what it's like....should get rid of some of that bounce.

 

[Joseph Kover]

Take off floorboards, extra noggins, 25mm ply, lots off screws, Ditra mat

 

[Joseph Kover]

Go to screwfix get some 20mm turbo gold screws fix them every 300mm using an impact driver and see what it's l

These are all structural-statical problems.not worth to risk,its all the traders fault from the moment he is touching it.

 

[Andy Allen]

It's a DIY job.......the op has been doing the job himself...

 

[Deleted member 46792]

The bounce has definitely reduced with extra screws. I just used the No More Ply screws. I'm now thinking that maybe vinyl tiles is the only solution without ripping up the NMP and half of the floorboards they are now at one with.

 

[Andy Allen]

TBH mate its difficult trying to make an assessment with out being there ...your dancing video help a bit and to me it looks like the nmp bouncing on the floor boards......personally I'm not a fan of nmp prefer hardie stuck down with a full bed of adhesive and screwed...
Choice is yours mate.....good luck.

 

[Qwerty]

Personally I have never used NMP as I put my faith in other products. Strengthen the floor as already stated if you can and it should help massively

 

[White Room]

Used NMP once, you need more glue than they advise...I'll stick with Hardie.

 

[Deleted member 46792]

Used NMP once, you need more glue than they advise...I'll stick with Hardie.

Yeah i am surprised. I think this has been the problem. I have now added screws and there is very little deflection as far as i can see.

 

[Andy Allen]

Go for it then....I would recommend using bal single part fast flex and bal wide joint grout with GT1 admix and 10mm notch trowel and back skim the tiles.

BTW....don't blame me if it fails

 

[Deleted member 46792]

Did a test area using bal single fast flex...its messy stuff and quite runny but so far so good.

I try not to blame anyone for anything, it rarely gets you very far. Unless its a question of losing things, and then it's always the Mrs hiding my stuff.

 

[WetSaw]

She's not hiding your stuff, mine is the same. They call it "tidying up"..

 

[Dan]

Don't mind me while I bump up some older but good threads. If you can contribute to the thread, go ahead. But if it's nothing for you then don't reply and it'll soon drop off the What's New page etc.
Worth linking to our new forum structure while I'm doing stuff:-

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