Customer is not taking advice.

[TheTiler]

Calling all good tilers out there please! I have a situation with a friend. He has had an ongoing extension project harboured by bad weather (rain and freezing temps). However, a fairly large (30 sqm) solid T&C floor had been prepared for tiling with 8mm ply on T&G prior to heavy rains which caused the unfinished roof to leak and took down the ceilings with extensive water hitting the plywood floor. Added to this is that plasterers have since contaminated the floor with a millimetre or so of plaster dust and dirt. There has been a large de-humidifier and a couple of small heaters in the room, but no central heating to the house. Even though the customer (my friend) thinks that a scrub of the plywood and a general heating using electric heaters would be enough, I think the whole of the plywood needs to be stripped up, the boards completely dried, kitchen fitted and room acclimatised once the C/H is in, then re-plywooded and tiled then and only then. Can you please advice (he's fitting 600x600 polished porcelain!).

 

[TheTiler]

P.S - He wants it laying in temps barely above 10 deg C. please give me some back up that this a bad idea!

 

[nybor62]

1st thing 8 mm ply is no good for a starter, min 15 mm wbp ply over laid with min 6mm cement boards,
its not a problem that the kitchen is not fitted ,as the tiles can be protected before fitting commences, but as you say it is freezing at the moment and set to get colder. get some heat into the building

 

[jay]

You are the tiler he is the customer if it cant be done to your standard (re prep work) then leave him to it
remember your name is on the finished job

 

[DHTiling]

Not sure where you are getting 10dgs cel at. Bloody freezing this week. Lol.

That substrate is crying for a disaster, as above min overlay with ply is 15mm BS5385.

You say T&G ? , is this floor boards or chipboard ?

Is this onto joists ?

How thick is this ?

 

[Qwerty]

I have just finished a conservatory (with fan heater in) at 5 degrees c.......which is the min temp alot of adhesives can be used. It dried overnight (rapidset!), but the grout took forever :mad2:

Do not tile in these temps!..... and do not tile onto 6mm ply either. Can the client not replace the T&G with 15mm+ ply? This could then be overboarded with backer boards ready to tile

 

[TheTiler]

Hi Dave, thanks for getting back to me.

It's about 10 degs, but only for the heaters which would be on of course.

The floor is T&G floorboards onto joists which are overlaid with 8-9mm plywood screwed down every 150mm (not done by myself). I think we're all aware of the BS's, and adhesive manufacturers requirements on the thickness of plywood, but I've always used 9-12mm plywood ON THE CONDITION that the floor doesn't show any bounce in it when carrying out a walk/jump test with a glass of water resting on the floor. I also look at the size of the customer and his family :lol:. If I'm concerned, I'll up the grade of adhesive I'm using to a 2-part rubber crumb. Although this may triple the price of the adhesive and grout, it works out about the same price of going the route of overlaying with 15 mm and creating a 30 mm ugly step into the next room (I've also found that planing that much off the bottom of a cheap non-solid door means that effectively the door no longer has any supporting timber at the bottom left any longer!)

Anyway, that's not what I'm concerned about. I'm properly concerned about the contamination of the floor with plaster dust (beyond the quick clean that the customer thinks will make it good), and the fact that the floor may still be retaining moisture, which I suspect will shrink back once the house if fully centrally heated and cause an already weak tile-adhesive bond to completely fail.

I talked to him again about my concerns, and he just said he needs to get them down.

So I've and cleaned up a patch of the floor in question, dried it, primed it, dried it and fixed a tester cut tile to check in the morning. I'll be surprised if it gives up much resistance, but if it does, what do I do? Write a disclaimer with him?

Arraagh!

 

[Mike]

Hi Dave, thanks for getting back to me.

It's about 10 degs, but only for the heaters which would be on of course.

The floor is T&G floorboards onto joists which are overlaid with 8-9mm plywood screwed down every 150mm (not done by myself). I think we're all aware of the BS's, and adhesive manufacturers requirements on the thickness of plywood, but I've always used 9-12mm plywood ON THE CONDITION that the floor doesn't show any bounce in it when carrying out a walk/jump test with a glass of water resting on the floor. I also look at the size of the customer and his family :lol:. If I'm concerned, I'll up the grade of adhesive I'm using to a 2-part rubber crumb. Although this may triple the price of the adhesive and grout, it works out about the same price of going the route of overlaying with 15 mm and creating a 30 mm ugly step into the next room (I've also found that planing that much off the bottom of a cheap non-solid door means that effectively the door no longer has any supporting timber at the bottom left any longer!)

Anyway, that's not what I'm concerned about. I'm properly concerned about the contamination of the floor with plaster dust (beyond the quick clean that the customer thinks will make it good), and the fact that the floor may still be retaining moisture, which I suspect will shrink back once the house if fully centrally heated and cause an already weak tile-adhesive bond to completely fail.

I talked to him again about my concerns, and he just said he needs to get them down.

So I've and cleaned up a patch of the floor in question, dried it, primed it, dried it and fixed a tester cut tile to check in the morning. I'll be surprised if it gives up much resistance, but if it does, what do I do? Write a disclaimer with him?

Arraagh!

you're right to have concerns but if you're that bothered, walk away. I can't see your mate changing anything and I've heard a disclaimer isn't worth the paper its written on



tapatalk on my HTC

 

[Ian]

Do you have to do the job? If you feel uncomfortable doing it, discuss it with your friend and tell him you aren't prepared to do it. If he's a good friend he'll understand, surely?

 

[Dan]

If you write a disclaimer you're still liable for the failure. (Double check that but I'm sure we've had this a few times on here.)

I'd say once that timber that's down got wet it needed to be replaced. And then there's the fact it's just too thin. Even a rubber crumb adhesive wont stop the timber falling apart under it. All that means is you'll just pick up lots of individual tiles with lots of timber attached to be back of them when it fails.

Let him get on with it and find a decent bit of work to be getting on with yourself.

 

[DHTiling]

Plywood thickness is also for extra moisture stability and not just deflection, if you want to proceed with 9mm ply , then i will leave you to it, we can only advice the correct way and not short cuts.. The sub-floor is goosed, simples as they say..

 

[kilty55]

if hes not going to listen then simply walk away.
i wouldnt risk tiling onto it you are correct not to also....bit concerned also that 9mm ply seems to be getting the go ahead...not thick enough and could also cause problems in the future as you know

it will be your phone that rings (friend or not) if it fails i would walk away mate

 

[TheTiler]

Thanks for the advice fellas. My gut feeling has been, and still is, to walk away. He's not an old friend or anything like that, just very know-it-all and what-with-the-fuss type bloke. Not had a failed floor yet in 7 years, and don't want one now methinks...

 

[TheTiler]

Just been thinking that the thickness's of (good condition!) boards used by tilers in reality, as opposed to those recommended by adhesive manufacturers might make for a good discussion? I'm not approving or disapproving anything by what I'm about to say, but...

When I was taught how to tile/prepare backgrounds at Leeds College of Building and when working for an old-timer master, it was accepted (but NOT in the book) that 9mm or even 6mm plywood would do the job providing that the floor was stable beneath. This wasn't a cost issue, but the fact that a hugely built up floor doesn't look good, and no customer will want a step out of choice. This was coming from a guy who had been tiling for 25 years and was very very good at it too, and a lecturer who tiled for 15 years and then taught (an unbelievable tiler for speed with pin-point accuracy). I didn't witness either of these fellas phones ringing for repairs and I've followed their "advice" for 7 years so far without any problems whatsoever. I made some friends while on my course, and they have never used any thickness above 12 mm, and I haven't heard them telling me of any disasters yet. I might add that when I was at College, we had a rep visit for tuition/promotion from Weber. He was an old fella who used to tile for 30 years and then went into using his knowledge for the development of their (then new) range of products. He didn't use 15mm during his career and was well aware that most tilers don't.

So here is my question. "Do you think that adhesive manufacturers recommend using vast thicknesses of boards just to ensure that they will never, ever, be to blame at the expense of a job not looking that great?"

I'd be really interested to hear from you please as it might just be stupid Yorkshiremen who do it! (me)

 

[Mike]

Just been thinking that the thickness's of (good condition!) boards used by tilers in reality, as opposed to those recommended by adhesive manufacturers might make for a good discussion? I'm not approving or disapproving anything by what I'm about to say, but...

When I was taught how to tile/prepare backgrounds at Leeds College of Building and when working for an old-timer master, it was accepted (but NOT in the book) that 9mm or even 6mm plywood would do the job providing that the floor was stable beneath. This wasn't a cost issue, but the fact that a hugely built up floor doesn't look good, and no customer will want a step out of choice. This was coming from a guy who had been tiling for 25 years and was very very good at it too, and a lecturer who tiled for 15 years and then taught (an unbelievable tiler for speed with pin-point accuracy). I didn't witness either of these fellas phones ringing for repairs and I've followed their "advice" for 7 years so far without any problems whatsoever. I made some friends while on my course, and they have never used any thickness above 12 mm, and I haven't heard them telling me of any disasters yet. I might add that when I was at College, we had a rep visit for tuition/promotion from Weber. He was an old fella who used to tile for 30 years and then went into using his knowledge for the development of their (then new) range of products. He didn't use 15mm during his career and was well aware that most tilers don't.

So here is my question. "Do you think that adhesive manufacturers recommend using vast thicknesses of boards just to ensure that they will never, ever, be to blame at the expense of a job not looking that great?"

I'd be really interested to hear from you please as it might just be stupid Yorkshiremen who do it! (me)

i bet they wouldn't tell you if they had a failure, like gamblers who only tell you when they win :smilewinkgrin: . there's many reasons as to why the boards need to be minimum 15mm and if you use thinner you're taking a risk of a failure. having a slight step into the bathroom is better than the tiles cracking or debonding

 

[JLM Tiling]

To be honest I'm interested in this too mate. I was trying to find out a few weeks ago about why weight limits are what they are and what are the actual results of the testing? And things like covering plasterboard in paintable waterproofer what are the weight limits then? It goes on. Basically we all know the rules and everything but even for the amount of failures we've all seen I've seen plenty of technically incorrect installations that haven't had any problems

 

[deankyall]

from a mapei technical evening,they told us that keraquick would go onto 6mm ply if mixed with latex plus,but not officially of course(how do they know this?)of course nobody on here is going to say that they do this,or ever tile on anything less than 15mm, or not agree with bs standards or manufacturers reccomendations,because just like them if it goes wrong ,and they gave the advice then .......!!!!!,but ive been tiling for near on 30 yrs and i would say i have only seen ply used at 15mm or above a handful of times,make of it what you will,bostik rep told me that they know full well that anything over twelve is hardly used,due to the reasons you point out,ie step etc,,anyway with new methods ie hardy backer board etc,then you can get a strong floor with less height.

 

[JLM Tiling]

Been subbing for a firm lately and the architect they are working for keeps speccing things like 25mm ply and other overkill requirements. From my point of view it's bloody marvellous!!

 

[jay]

Been subbing for a firm lately and the architect they are working for keeps speccing things like 25mm ply and other overkill requirements. From my point of view it's bloody marvellous!!

nice dream you can wake up now

 

[JLM Tiling]

You're just jealous Jay!! Lot of money over here and not been hit too hard by the economic downturn so fortunate in that respect