I'm in the middle of my thoughts on this one. on one hand, I am sympathetic for the stress you and your wife are going through. The amount they are trying to claim is totally inappropriate and disproportionate in my opinion. And as above, by law, they cannot make any claim against you unless they have given you the opportunity to resolve and you refuse.
But this is a specialised tiling project. Not one I would personally suggest a plumber take on without sufficient training specifically in thin porcelain and the correct knowledge of what preparation is required, no matter how much the customer leaned on you. Hindsight is a wonderful thing, and in hindsight, you'd have walked away on the understanding that you yourself knew before you had started, you were not experienced enough to take it on.
Only the wall fixing code of practice (
BS5385 Part1) was updated to eliminate ply as a suitable substrate. But for floors, 9mm ply is still not recommended as per BS5385 Part 3:2014 and never has been in past editions as far as I can recall. WPB ply of 15mm minimum thickness, screwed at 300mm intervals, is still allowed for floors although cement board would still be a better option. And for thin tiles, I'd be more comfortable with using 12mm Hardie instead of 6mm, purely for the rigidity required for the type of tile being used.
As above, for Ditra, the minimum tile thickness allowed is 5.5mm (as per Schluter's Ditra25 installation instructions). So in the knowledge that the tiles should have been between 4.8 and 5.5mm, fixing on Ditra was a significant risk. Before fixing, the tiles should have been inspected to ensure they are of suitable dimension/thickness for installation on the intended prep, before possibly going back to the supplier to resolve if the were not fit for the specific installation, or adjust the preparation method to suit (an alternative decoupler for example, or not plywood). If they were only 3.8mm you may have had a case for false advertising or being given incorrect information, but you've fitted them now, you've accepted them for what they are. By law, the supplier or factory is under no obligation to provide a resolution once the product is used, although they may offer assistance with a replacement product as goodwill.
Thin porcelain tiles are quite bendy over the length/width of a tile. I remember an image that someone posted a while back showing how flexible a 1200x600 can be under force. The adhesive is not designed to stretch to that extent, so under point loading, if the floor is not braced sufficiently or under the Ditra compressing, you are at risk of the adhesive shearing around the area of pressure.
If you can get it in writing from BAL or Schluter that the tiles were suitable to lay on Ditra, and 9mm ply, you may have some form of defence, but I fear even they would struggle against the TTA as they are both members, and BAL's head of technical is on the TTA's board of directors.
Although you haven't made it easy for yourself, I do wish you all the best in getting this sorted.
Thank you very much for taking your time to respond. It really is quite humbling and I am getting more answers to questions on this forum that anywhere else, including my solicitors, who I am paying £270 an hour plus VAT.
My solicitor is adamant than the customer does not have to give me the opportunity to put things right, especially when he has a TTA report stating that a tap test assumes all tiles may have debonded. Only 2 wall tiles in 3 bathrooms have moved, there does not appear to be any signs of movement to any floor tiles at all so I think that the Ditra 25 is fine.
I appreciate that Ditra 25 requires tiles at least 5.5mm and I did not measure them as I did not supply them, I also did not own or carry a digital caliper, but have bought one since.
Both of the massively expensive quotes that the customer has obtained from large organisations both also specify using the Ditra 25 with the replacement tiles!
Despite my email contract stating that I must be informed of all aspects of bathroom products/tiles etc that is intended to be fitted before starting works, so that I could ensure that adequate time and costs are allowed to protect both parties and indeed that I was familiar or skilled to fit whatever was being supplied, the customer NEVER provided this information, despite various reminders and requests. His response was always "well it is what it is"
As the first stage of works was undertaking the heating & hot water, pressure boosting, water softener etc, which would take a few weeks as it was a big property on 3 floors plus cellar, I had to remove one bathroom upstairs and take up the floor to adapt all hot & cold pipes plus install new heating pipes for different zones, so in effect, I had already started on 1 bathroom without still knowing what was going to be fitted.
As you say hindsight is a wonderful thing and being a trusting person I have always got on well with customers but this client seemed hell bent on not giving me any information at all. I never found out who the tile supplier was until I received the legal papers in the post.
The boxes containing the tiles said Porcelobobo or similar but they were supplied by Porcel-thin.com in Rotherhithe London
The tiles are manufactured in the far east and imported by Porcel-thin.com
I first contacted Ray Smith the MD of Porcel-thin after receiving the TTA report and stated that I have 3.81mm tiles but he immediately said that they couldn't possibly be his tiles as all their tiles range from 4.8 to 5.5mm. He assumed that they were his competitors tiles which are cheaper mesh backed and advised me to avoid them as they would be too fragile and possibly lead to de-bonding!
When I phoned him a second time and made it clear that Porcel-thin had supplied the tiles, he changed his position stating that the tiles would be fine, although he still didn't believe that they could possibly be as thin as 3.81mm.
One company that I called, when searching for a tile expert, advised me to check if the tiles were CE certified, which they are, however all tiles sent for testing were between 4.78 to 4.93, therefore the tiles I was using were up to almost 30% thinner than those sent for CE testing.
The really annoying thing is that Porcel-thin show on their web-site that he provides free in-house training, taking just a couple of hours.
Had I known in advance, I could easily have attended and learnt more about these specialist tiles, rather than learn on the job
Looking back, I think that I have been played all along
As for what happens now, I'm advised to make a Part 36 offer which, if is accepted, will put an end to the matter before Court costs and barristers costs spiral out of control, although if i do this, i am also agreeing to pay all his costs, including expert fees for the past year.
I have and have always had public liability insurance of £10m but I do not know anyone other than doctors, architects etc that have professional indemnity insurance, which, when started must continue for 6 years regardless if you stop trading.
I would urge everyone to simply set up a limited company