Tiled my bathroom floor 3yrs ago but about a week ago when walking on floor heard loud crack,never noticed anything untoward,wife noticed hairline crack in 2 places from wall to wall when washing the floor ? (22mm chipboard Wooden floor,9.5mm ply ring nailed,floor bonded with pva before tiling,flexibond adhesive used),tiles are 600mm x 300mm,why would this happen 3yrs after laying.

Hmmmm...... it shouldn't really, 3 years on you say? and straight across? sounds like you ticked all the boxes, I’m stumped sorry! Lift & look? weak joists bouncing over time perhaps?

PVA is not suitable for using as a primer for the simple reason that it is a sealer and can react with tile adhesive. Whether that could take 3 years to show as a problem , rather than more quickly.

Could just be that the floor was not strong enough for tiling onto in the first place and it has finally decided to let you know. especially the case if the cracks are running parallel to joists.

Schluter Ditra matt is the daddy of all overlayments for tiling onto, if the floor has a fair amount of deflection.

Sounds as if it may be a case of floor up and doing again. If you overply for cheapness then use 12mm minimum, or use Nichols and Clarke plastic ply.

" especially the case if the cracks are running parallel to joists."

The cracks are running in opposite direction to the floor joists (300mm),this is the 3rd time the floor has been tiled (no probs berfore)however these are the largest tiles i,ve used.The only thing i can think of but unlikely is we have had temperatures of -15 but have kept heating on at a peep all through this

Is the bathroom on the ground floor, what size tiles, did you use a cement based adhesive?

Have you got a link you can put in here for the tiles?.

Could also be that you have a leak somewhere. Just replaced a tiled floor a few months back where that had caused cracking.

ahhhh..... Ditra matting, yes the orange stuff, many moons (20 years ago) it was then I learned I should really have sealed the porous hand made terracotta tiles before slapping black grout over them, they took longer to clean than they did to lay!
Live & learn eh? lol

Depending on where you live, there was an earthquake in England last week. Could have something to do with it, although it was only a light one and not felt, the same thing happened a few years ago and London was affected. Some of my sisters floor boards actually came loose and needed fixing back down during that one.

It is amazing what you remember whilst going to pets at home.

Earthquake ! ROYAL................. lol, I was just starting to trust you! now i'm back to square one!
P.S
I think you should post up a pic of when you were in Saudi? ect (can't remember where it was) I know this is a DIY forum, but you must of been proud of your time out there mate? besides...... im a nosey fkr!

It was on the news about the earthquake, last Wednesday or Thursday on the radio. We get a few of them here but not normally felt and only a minimal amount of damage.

Most of my pics from Iraq were lost on my old computer when it crashed. Still have the files but can't access them lol. They had all the pics of rogues gallery material from sites I visited when I switched roles during my last 9 months there. That is a different topic though.

Wasn't it in Cumbria (the earthquake, not your radio)?

_________________
Mike
http://rebuildingatimberbungalow.blogspot.com/
any advice welcome

I can't remember lol

Yep, Cumbria.

21st December.

http://www.bbc.co.uk/news/uk-12056634