Tiling Bathroom Chipboard Floor Floor

[Alexb]

Hi, I was told that the bathroom chipboard floor has to be laid with plywood of at least 9 mm thick, before tiles are laid. In my mother's house some ago the bathroom chipwood floor was overlaid with 5mm plywood. Is it mandatory standard to use 9mm ply on bathroom chipwood floor? Thanks

 

[Old Mod]

Hi and welcome to the forum Alex!
If u get a moment, it'd be kool if u were to introduce yourself to the members so that we know who you are and why you're here.
It also lets members of the public know also, that this is the right place to come with their problems, and it's not just for Proffesionals.
U can do that here:

Welcome Forum | New Members Say Hi Here

Anyway your question,
Sounds like u've been given common misleading info in the past.
If u are overboarding existing chipboard flooring, once you're convinced that it is sound and securely fixed (with no bounce!)
You can overboard with a product like Hardiebacker.
It's effectively a cement board that does not expand and contract with heat/cold and is water RESISTANT not PROOF.
Timber as a sub floor will do all of the above, typically causing your floor to de-bond and fail.
So covering your existing floor with this or similar products will help combat that!
These products are glued with tile adhesive and mechanically fixed with screws also.
BUT it will not help against deflection (bounce) the single biggest cause of failed flooring.
So make sure your sub floor is deflection free!

 

[Alexb]

Hi and welcome to the forum Alex!
If u get a moment, it'd be kool if u were to introduce yourself to the members so that we know who you are and why you're here.
It also lets members of the public know also, that this is the right place to come with their problems, and it's not just for Proffesionals.
U can do that here:

Welcome Forum | New Members Say Hi Here

Anyway your question,
Sounds like u've been given common misleading info in the past.
If u are overboarding existing chipboard flooring, once you're convinced that it is sound and securely fixed (with no bounce!)
You can overboard with a product like Hardiebacker.
It's effectively a cement board that does not expand and contract with heat/cold and is water RESISTANT not PROOF.
Timber as a sub floor will do all of the above, typically causing your floor to de-bond and fail.
So covering your existing floor with this or similar products will help combat that!
These products are glued with tile adhesive and mechanically fixed with screws also.
BUT it will not help against deflection (bounce) the single biggest cause of failed flooring.
So make sure your sub floor is deflection free!

3 Fall thanks for the reply and the advice, I will introduce myself properly once I have a bit more time.

 

[Alexb]

3 Fall thanks for the reply and the advice, I will introduce myself properly once I have a bit more time.[/QUOTE
But I still would like to know if there is any mandatory requirement in tiling over chipwood boards, and if there is, do I have a case to pursue it with trading standards?

 

[StevieBoy]

Or alternatively you could do it like I do.

Over board with 5.5mm plywood, screw every 100mm, prime with SBR, then tile with Toppfix 2 part flexible adhesive, making sure you back skim and finally grout with flexible grout.

Not had one fail in 8 years.

 

[Alexb]

Or alternatively you could do it like I do.

Over board with 5.5mm plywood, screw every 100mm, prime with SBR, then tile with Toppfix 2 part flexible adhesive, making sure you back skim and finally grout with flexible grout.

Not had one fail in 8 years.

Thanks mate

 

[SJPurdy]

Pursue what with trading standards?

I wouldn't recommend using thin (eg 6mm) ply for overboarding as:
1. if there is any movement the screws will pull through the ply;
2. it adds very little in the way of strength to the floor;

Some two part adhesive manufacturers do/did state that a minimum of 6mm for ply overboard, but they also say/said can fix directly to the wood (which I have done in the past without problems but would not (and do not recommend anyone else to do) now).
3_falls post #2 above gives good advice - if floor is rigid then overlay with correctly fixed eg 6mm Hardie board then tile with flex addy and grout.

 

[Alexb]

Pursue what with trading standards?

I wouldn't recommend using thin (eg 6mm) ply for overboarding as:
1. if there is any movement the screws will pull through the ply;
2. it adds very little in the way of strength to the floor;

Some two part adhesive manufacturers do/did state that a minimum of 6mm for ply overboard, but they also say/said can fix directly to the wood (which I have done in the past without problems but would not (and do not recommend anyone else to do) now).
3_falls post #2 above gives good advice - if floor is rigid then overlay with correctly fixed eg 6mm Hardie board then tile with flex addy and grout.

Thanks SJPurdy

 

[Dave]

Or alternatively you could do it like I do.

Over board with 5.5mm plywood, screw every 100mm, prime with SBR, then tile with Toppfix 2 part flexible adhesive, making sure you back skim and finally grout with flexible grout.

Not had one fail in 8 years.

The amount of times I hear that excuse for using incorrect preparation materials. I've done it this way for yrs and never had a failure ffs.

 

[StevieBoy]

The amount of times I hear that excuse for using incorrect preparation materials. I've done it this way for yrs and never had a failure ffs.

Proof is in the pudding pal.

And for the record who made you judge and jury ?

 

[StevieBoy]

Pursue what with trading standards?

I wouldn't recommend using thin (eg 6mm) ply for overboarding as:
1. if there is any movement the screws will pull through the ply;
2. it adds very little in the way of strength to the floor;

Some two part adhesive manufacturers do/did state that a minimum of 6mm for ply overboard, but they also say/said can fix directly to the wood (which I have done in the past without problems but would not (and do not recommend anyone else to do) now).
3_falls post #2 above gives good advice - if floor is rigid then overlay with correctly fixed eg 6mm Hardie board then tile with flex addy and grout.

Absolutely incorrect.

5.5mm ply, screwed at 100mm intervals stiffens the floor up like you would not believe.

What are you on about movement making the screws pull through the ply ???

Maybe if there was an earthquake then yes lol.

 

[Dave]

Proof is in the pudding pal.

And for the record who made you judge and jury ?

You've answered your own question lol.

 

[Ian]

Absolutely incorrect.

5.5mm ply, screwed at 100mm intervals stiffens the floor up like you would not believe.

What are you on about movement making the screws pull through the ply ???

Maybe if there was an earthquake then yes lol.

So what you're saying is, ignore what the adhesive manufacturers recommend and ignore British standards. Do you think these adhesive manufacturers test all their products for fun? I've seen plenty of floors that have failed on 6mm ply so I'll guarantee some of yours have, you probably just don't know it. How many of your floors have you revisited after say a year or so?

 

[Dave]

For others reading this ....

An exert from section 3 : bs:5385.


Quote:


 Ensure the sub-floor construction will be capable of supporting added load of tiling system plus anticipated static/dynamic loading in service.

 The sub-floor should be rigid and stable with respect to the normal humidity levels; noggings may be required between joists to ensure rigidity.

 Ventilation of the underside of the timber sub-floor must be adequate and effective damp proof courses correctly located.

 Select an appropriate sheet or board of adequate thickness to overlay the sub-floor. (15mm is the minimum recommended in Part 3 of BS5385)

 The wood-based sheets and boards should be conditioned to a moisture content appropriate for the ultimate service conditions, as detailed in 4.1.1.

 The moisture content of all wood-based products should be checked.
 The lower face and edges of the wood-based sheet or board should be sealed .


 

[StevieBoy]

For others reading this ....

An exert from section 3 : bs:5385.


Quote:


 Ensure the sub-floor construction will be capable of supporting added load of tiling system plus anticipated static/dynamic loading in service.

 The sub-floor should be rigid and stable with respect to the normal humidity levels; noggings may be required between joists to ensure rigidity.

 Ventilation of the underside of the timber sub-floor must be adequate and effective damp proof courses correctly located.

 Select an appropriate sheet or board of adequate thickness to overlay the sub-floor. (15mm is the minimum recommended in Part 3 of BS5385)

 The wood-based sheets and boards should be conditioned to a moisture content appropriate for the ultimate service conditions, as detailed in 4.1.1.

 The moisture content of all wood-based products should be checked.
 The lower face and edges of the wood-based sheet or board should be sealed .


Text book crap yet again lol

 

[StevieBoy]

So what you're saying is, ignore what the adhesive manufacturers recommend and ignore British standards. Do you think these adhesive manufacturers test all their products for fun? I've seen plenty of floors that have failed on 6mm ply so I'll guarantee some of yours have, you probably just don't know it. How many of your floors have you revisited after say a year or so?

Look let's not get into the first part, because that's being silly.

No, I don't make a point of phoning or going back to a customer after a year or so as you say, to ask - hey has your floor failed? - Who would?

All I can say is that none of them have been back in contact with me after I have used the plywood and 2 part addy method to say they have.

How much guarantee do you give with your work then? 20 years or so lol ?

 

[StevieBoy]

You've answered your own question lol.

Fine then isn't it?

 

[Dave]

Text book crap yet again lol

Ok Instead of sitting behind your keyboard , you explain why technically why your method works and will never fail , don't just say you've always done it that way crap , explain why it works and why every adhesive comp etc etc is wrong ?

 

[Ian]

Look let's not get into the first part, because that's being silly.

No, I don't make a point of phoning or going back to a customer after a year or so as you say, to ask - hey has your floor failed? - Who would?

All I can say is that none of them have been back in contact with me after I have used the plywood and 2 part addy method to say they have.

How much guarantee do you give with your work then? 20 years or so lol ?

I'd like to think my work will last until the customer gets bored of it not because they have to change it because it's coming up. The thing that gets me is that you keep advising fixing methods that no one has ever recommended! Why would you make up your own rules? If you can find me any written document anywhere where it recommends fixing to 6mm ply or indeed using the cow pat fixing method, I'll take it all back. Simply saying that you've always done it like that and never had a problem, really doesn't wash, for all you know, your customers tiling has failed and they don't want you back in their home to rectify it. I get a lot of recommendation and repeat work, so I'm fortunate enough to get to see work I've done several years ago and guess what, it's all ok and further more, it wasn't fitted with cow pats over ply wood.

 

[StevieBoy]

Ok, providing the sub floor is sufficiently rigid first that's where to start.
If not, it needs to be. Then with the plywood screwed every 100mm, that strengthens the floor completely and ties everything together.

Prime with SBR, this gives the surface extra adhesion.
Tile using 2 part flexible adhesive. This type of adhesive is rubberised, and allows for any movement.
Cement based flexible adhesives, set hard - where as 2 part sets, but not rock hard so acts as a cushion for the tiles to sit onto.

I don't know how else I can make it any clearer.

 

[StevieBoy]

I'd like to think my work will last until the customer gets bored of it not because they have to change it because it's coming up. The thing that gets me is that you keep advising fixing methods that no one has ever recommended! Why would you make up your own rules? If you can find me any written document anywhere where it recommends fixing to 6mm ply or indeed using the cow pat fixing method, I'll take it all back. Simply saying that you've always done it like that and never had a problem, really doesn't wash, for all you know, your customers tiling has failed and they don't want you back in their home to rectify it. I get a lot of recommendation and repeat work, so I'm fortunate enough to get to see work I've done several years ago and guess what, it's all ok and further more, it wasn't fitted with cow pats over ply wood.

Who mentioned cow pats on plywood? I certainly never did, as usually plywood floors are pretty level, so don't require that skill full way of doing it.

So if you were fixing say 600x300's half bond onto newly plastered walls, you'd lay to a spread would you and not build out?
You have bigger lips than Elvis lol.

And also, most of my work is repeat custom and word of mouth so I must be doing something right.

You can think / say what you like, I'm not too bothered.

My methods work for me, always have upto now and that's what matters.

 

[Ian]

I think the fact that you've been pulled up by several members regarding your fixing methods, should make you think a bit more about what you're doing. Anyone with an ounce of professionalism or pride in their work wouldn't even dream of fitting tiles in that fashion. Whether it works for you or not is irrelevant, it's wrong and isn't recommended by any manufacturers. Basically what you're saying is you know what's recommended but, you don't give a toss. Why, when there are so many proven methods and products out there, would you choose not to use them? As I said before, find me any literature that recommends fixing tiles to 6mm ply and I'll take it all back.

 

[SJPurdy]

Hi, I was told that the bathroom chipboard floor has to be laid with plywood of at least 9 mm thick, before tiles are laid. In my mother's house some ago the bathroom chipwood floor was overlaid with 5mm plywood. Is it mandatory standard to use 9mm ply on bathroom chipwood floor? Thanks

Well the short answer is "no". British standards recommends 15mm (with suitable adhesive, grout and priming system.
I used to fix myself onto 9mm ply using the more expensive higher spec 2 part adhesive systems and as far as I know they didn't fail.
Before that I used the two part directly onto the chipboard (adhesive makers used to say it was ok to do it this way) it wasn't a reliable method. I have seen many fails on 12mm and thinner ply's when the cheaper less flexible adhesives were used (at one time adhesive makers said 12mm was ok but they don't now - I did loads of floors this way and had no come backs).
I have also seen a 6mm ply floor that was being replaced even though a 2 part adhesive was used - the boards could be easily lifted leaving the screws in the sub-floor.

BUT the industry has moved on, there are now the already mentioned tile backer boards which add stability to the floor in a much thinner format than the plywood (eg 6mm compared to 15mm). They are not affected by water (although obviously the chipboard below will still be). They have been designed for this purpose and have been tested as being suitable for this purpose. They are readily available and cost effective so why use Ply?

 

[One Day]

Threads like this make me moan about the tile association again. I respect anyone's right to tackle a job the way they want to. Fixing cow pats to 6mm ply if they want, so long as they take responsibility. But those of us who want to do things 'properly' and by that I mean no offence. (If you take offence at us using the word 'properly' then you really need to go away and think why you're offended by it!) any way, I joined the tile association hoping that it would help to differentiate me and my methods from the 6mm ply groups out there. It didn't. Total waste of time and money. They have no interest in the likes of us on here.
Arguing on internet forums like this is pointless. A tradesman is only as good as his last job.

 

[bcd-87]

@Dave @Bri @StevieBoy There's only one way to settle this