Floor tiles on chipboard floor

[Bennyboy76]

Hi all

I'm hoping you can give me a steer on this one.

I have a 10-year old townhouse with the kitchen on the 1st floor. The builders (numptys that they were) laid the kitchen floor tiles staright onto chipboard. Yep, you guessed it, numerous lose and broken tiles 10yrs later.

Am in the process of getting quotes for new kitchen but want to ensure that I am getting the right work undertaken re the floor, or indeed doing the right prep. myself. I've already learned that asking a kitchen fitter for his advice re tiling won't get me the correct answer but before I approach a tiler I want to be sure on what the correct course of action is so I can make sure I'm not being told rubbish.

There is some deflection in the floor, although I've not looked at how far apart the joists are, I am guessing/hoping that Wimpey built the house with them the right space between them given that it's only 10yrs old? Most of the tiles that have cracked have done so I think because they have come away from the chipboard as it has moved over time.

So, questions for you guys if I could please:-

1. Is it ok to overlay the existing chipboard or best to take it up and replace with ply screwed directly onto the joists? From what I've seen of the floor it looks to be in reasonable nick - no flood damage etc.
2. If overlaying, best to use marine ply or one of the tile backer board products thats out there?
3. If ply, what depth?
4. If backerboard, what depth and make do you suggest?
5. If overlaying, do I screw the ply through the chipboard and into the joists or just into the chip? I've heard differing stories on this one so just want to check. For me just screwing into the chip is better as I don't have to locate all of the joists underneath...
6. If ply - do i need to leave expansion gaps around the edges and also between each sheet of ply? Size of any gaps?
7. Will the ply stop/reduce the deflection sufficiently? Not done the glass of water test yet but I can definitely see that it gives a bit.
8. Am thinking 60x60 polished porcelain tiles - not certain if that makes a difference of not to the recomendations from you guys.
9. Any appropriate descriptions for the original builders would also help please ;-)

Fortunately, in helping me with the above, you can rest assured that your advice will be put to great use as I also have a 2nd floor bathroom and ensuite to do due to the same issue.

Thanks in advance all

Ben

Ben

 

[peteablard]

Hi Ben, the first thing you need to do is make the floor deflection free, the best way is to remove the chipboard and put extra supports between the joists. Then ply the floor with ideally 18mm WBP ply but minimum 15mm, I'd screw it every 250mm. Then overboard with hardie backer, this needs to be set on adhesive and also screwed

 

[Perry]

have you joists or have you a floating floor ?

 

[Bennyboy76]

Hi pjc. Sorry Not sure of the question but i know that the chipboard under the existing tiles is screwed/nailed directly to the joists underneath. In the room underneath the plasterboard for the ceiling is nailed to the same joists.

 

[Bennyboy76]

Thank peteab. Is this what noggins are? Basically cut similar size wood to the joists and lay at tangents between each joist? How/why does that make the floor more stable? Cheers

 

[Ceramico tiling]

noggins spread the deflective force to a larger area on the floor.So instead of the single joist deflecting,, noggins tie that joist to the others more effectively.They also prevent the plywood from deflecting(when a big fat person stands on it) as it is supported more effectively.For them to be most effective cut them 1mm bigger than the spacings between the joists and force them in all in.This will tension all the joists up nicely.