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

 

[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.