Cracked Tiles over Bonding Plaster

[Edd Barker]

Hi all,

We had our bathroom fully re-done approx 2 months ago. 1880's property, the previous tiles around the shower area had failed, due to water ingress. All tiles, old plasterboard etc were removed. The two brick walls were then bonding plastered. The side of the chimney breast was built out with marine ply. The final tiled surface around the shower was painted MDF already.

The bonding plaster was tiled directly onto, I would estimate with around 3-4 days to dry/cure before tiling took place. I know that in some places the bonding was an inch thick, due to very uneven walls. It was not tanked, I did query this but was told it was not necessary.

The plywood and painted MDF sections were also directly tiled onto.

Within a month, we had a long, hairline horizontal crack in the grout line on the brick, bonding plastered wall. The bathroom fitter applied more grout over the top.

Today I have noticed a single, long vertical crack through the middle of the tiles, from top to bottom. Same wall. The crack follows grout lines, then, the tiles have cracked vertically down the middle.

I am aware (too late!) that bonding plaster is not a suitable substrate for tiling onto. Could anyone advise the best course of action to remedy this problem. The bathroom fitter is coming round tomorrow to inspect, so I would like some professional opinions to present to him on how to move forward. If someone could tell me what should have been done to prepare the very old brick walls for tiling, that would be much appreciated.

I can attach photos if required.

Many thanks,

Edward

 

[WetSaw]

Bonding, plywood and MDF as substrates? All wrong.

 

[Old Mod]

Images would be helpful.

 

[Dumbo]

I'm not keen on thermonuclear approach of stripping it all out and starting again as is often said but I think the wall with bonding should be stripped down back to block and boarded and then retiled . The reason i dont say that about the other walls is who knows you may be lucky , I know most on here have stripped rooms out that in theory shouldn't of lasted as long as they have .

 

[Edd Barker]

Pictures to further illustrate:

Close up of the cracked tiles. Tricky to show. This carries on up the entire wall, alternating cracked tile, cracked vertical grout line.

These two walls in blue; the long wall and the wall with the shower & mixer on, were re-done in bonding plaster. Not tanked. primed with waterproof PVA.

This cupboard was here before the bathroom was re-done. It was previously just painted MDF at the end of the shower. We decided to keep it, and so the painted MDF was tiled over. It was not tanked.

This small wall is the side of the chimney breast, the bath is squeezed in the gap alongside the chimney breast. This return was built out (chimney breast made approx 25mm wider) over the bath, to allow the glass screen to be fitted along the bath line. The bath was fitted, and then plastered on to.

Any further questions please let me know.

Many thanks for the replies so far.

Edd

 

[Old Mod]

Have you paid the contractor?
That’s probably a daft question, shame.
I’m not sure if I can actually think of any others sins that could’ve been committed.
Sorry, not what you want to hear I know.

Tiling to bonding, NO.
Tiling to MDF NO
Tiling to paint NO
Pva is NOT waterproof and should NOT be used as a tile primer.
When PVA gets wet it becomes ‘live’ again and is useless as a primer.
A proper acrylic tile primer should be used if something needs priming.
Wooden substrates are now excluded from being used as tile surfaces, by BS5385, they should be overboarded with a 6mm tile backer board glued and screwed at very least, if walls are solid, and not just studwork.
How did they build out the 25mm one end?
Should have centred bath between two short walls and covered walls with 12mm tile backer board, glued and screwed.
Even plaster in a wet area is not a particularly clever thing to do without tanking.
Tiling to paint, you’re only relying on bond of paint to timber to hold tiles on, effectively you’re just hoping paint doesn’t let go of the wooden substrate.
Again, just over boarding with a backer board and mechanically fixed (screwed) would have solved this potential problem.
If this is a long term home, then I’d consider starting over.
Or at very least as Jerry above says, deal with the wall that is bonding only.
Should be hacked back to brick/block, and either studwork fitted. 300 centers and a 20mm wedi style board fitted.
Or strip back and dot and dab thick wedi board direct to brickwork. Sizes go up to 100mm thick at least. I’m sure you’ll find a thickness close to what you have know.
(and not a dab in each corner either, everywhere lots of dabs)
Stuck with tile adhesive NOT plasterboard adhesive.
Then use screws when adhesive has set.
Not sure how many per board with this method, but it’s not many, supplier should be able to help.

The others you may get away with for a time.

If you use Wedi style boards, these are waterproof and designed for tiles.
Spread adhesive on wall and fit like a big tile.
Then fix using screws long enough to reach either brick wall or timber, using wedi style washers.
The wedi style boards are made by many companies and are cheaper than wedi.
Google will help you no problem even using those terms.
The washers prevent screws pulling thro.
Then to totally waterproof it, tape all joints and over every screw, with suitable tape, then it’s fully waterproofed.
It’s a very simple operation.




Do you know what type of adhesive was used?
Tub or bagged powder?

 

[acaciaguy]

As above. It’s all wrong really. And all badly wrong. It should all come out and be redone for peace of mind and longevity. Things can last even when wrong but you have already had issues.

If you are going to redo one wall may aswell do all

 

[Edd Barker]

Hi 3-Fall,

Many thanks for the comprehensive reply. No, it is not what I want to hear, but to be honest it is what I expected!

The tile adhesive was Topps Tiles Slow Set Flexible Grey.

Thanks to others who have responded also.

Edd

 

[Old Mod]

For anyone who’s interested, I received a forum PM a few days ago from Edd stating that thanks to this thread, the bathroom fitter had agreed to rip out back to brickwork and re-install from scratch.
I did ask him to mention it in here, however it appears he may have forgotten.
So I just thought I’d mention it and say thanks to all those who contributed, even in the way of just likes or other ratings.
It’s just good to know that we sometimes make a difference.
Thanks again.

 

[Edd Barker]

Hello,

Not forgotten, I just thought I’d wait till it actually happened before I posted! Many thanks for the advice and suggestions given. Once work is underway I will let everyone know.

Thanks again,

Edd

 

[Old Mod]

Hello,

Not forgotten, I just thought I’d wait till it actually happened before I posted! Many thanks for the advice and suggestions given. Once work is underway I will let everyone know.

Thanks again,

Edd

Apologies for making assumptions Edd.
Thanks for coming back, look forward to hearing more.

 

[On one]

@Edd Barker
What was the reason for the blue and white tile grout joints being offset(horizontally)?

 

[Edd Barker]

3Fall - No apology required! As the bathroom is still useable, we have told the fitter not to rush to squeeze us in. So it could be a month or two before anything happens.

Wrighty - the blue and white tiles are different sizes! We did not realise this until the fitter told us. We chose the blue first, but did not like the whites that the same manufacturer offered, so we went with another that were (supposedly) the same size from another maker. Obviously the tolerances in manufacturing have added up to an offset. Lesson learnt on that one. As the two walls are only visible together from one specific angle, we will get over it.

Edd

 

[On one]

I see!
It's something I have had to tell some customers in the past.....not all tiles that are called 600mm x 300m are 600mm x 300mm!

 

[Tony_C]

When retiling the blue tiles you could also avoid those slithers at the ceiling by asking the tiler to go a full tile off the bath if its no longer to meet a bond from the white tiles. Just a thought if its being redone anyway. Unless it is just one wall being redone then nevermind