Stains on white limestone floor

Hi all

Got a bit of a problem with a limestone floor and hoping you can advise and help. Here's the story...

I laid 50mts of 600mm sq honed limestone tiles at the end of November in a full house refurb. Heated screed had been down 4 months and fully tested. Screed was almost level so no SLC used. Instead spread adhesive - rapid setting white flexi - to back of tile and screed using a square 10mm notch. Nice bed with plenty of scope for the odd bump. Sealed once with Lithofin stain stop and grouted. All spot on and no probs. Customer happy so job complete.

Had a call from client yesterday. In mid December the decorating/building contractors covered the floor with Cordek, taped the joints and carried on with their works. However it seems they forgot to turn off the underfloor heating! (as advised to client and contractors) Needless to say that when they have taken up the sheeting there is puddles of condensation, what looks like scorch marks and its a right state. Pics attached.

The client has come to me asking for advice and I don't really know what to suggest. Looking back over old posts on here it seems the floor is ruined and no chance of salvage. Is there a product that would help remove the marks? Would re-grinding and honing the tiles help? I've gently sanded a tile with marks on and they don't seem to be just on the surface marks. The contractors have admitted liability so no probs there. We are just looking for a solution that doesn't involve ripping it up and replacing it. . . if there is one?

Thanks in advance

dont look good pal, im sure the stone experts will have some answers for you , what i will say is one coat of sealer was not enough imo, how soon was ufh heating put on after tiling was finished

Not good ,how long since the floor was uncovered (as it may and i state MAY) dry out .

also was the floor run up to temp then cooled down before tiling
or is that what you mean by fully tested

Yeah I was due to return to add more sealer once the sheeting was up. I was put on a tight deadline due to stairs and a flash glass walkway going in above so I had to be out. I thought one heavy coat of sealer would give it some protection especially as it was being covered over.
Floor was uncovered Sat and I took the pics last night. I'm not sure its damp marks so much as staining. The marks are like brown water marks/rings.
I'm not sure about the heating after tiling. Client doesn't know and contractor said it was brought up slowly but who knows.
Yeah the screed had cooled before I tiled.

Had a similar situation years ago when i was a contracts manager for a tiling contractor, the floor had been "protected" with hard board by the main contractor, when the hard board was lifted there were similar brown stains on the limestone. If my memory serves me right the main contractor got a specialist stone contractor to buff/polish away the stains and the floor was perfect. This was in Edinburgh and i'm sorry i dont have any info on the specialist stone contractor, but it was possible to remove the stains, how long it took and how much it cost was never disclosed to us. Hope this helps good luck.

Thanks for the advice.
Yeah I'm starting to think either re-honing the surface might do it or a total rip up and replace.
Lithofin have nothing that might help remove the stains. I'm waiting for a company to come and see the floor regarding re-finishing the surface but they don't seem too hopeful either. It all depends on how deep the staining is and unfortunately you cant tell without trying. They wont advise of cost until they see the floor/work out how much needs to be removed to get to clean fresh stone. Sounds like it could be very expensive if it goes deep into the tile and an easy way for the price to go up and up.
Maybe it would be easier to just rip up and replace. Atleast that way we can work out the total cost and know where we stand. Also this way we know the time frame of works whereas we could wait 2/3 weeks for the re-finishing to be done only to find out it isn't going to work and then be waiting again for new tiles to arrive and struggling to fit it in before client moves in on April 1st!
Does anyone else have any ideas? I've got to get back to the client on Monday with a plan.

Hi..

So you only sealed it once..?

just picked this up.
I had a similar problem last year where I had finished a job with polished jura.
I told contractor to only cover with building paper to let floor breathe.
They duly covered whole floor with building paper, no problem.
Building works went on for another 6 months.
about a month after paper down, the floor got covered on top of paper with cordex, the other half with hardboard.
heating got turned on for four months .
when covers removed the area with cordex had sweated and moisture got trapped under paper and cordex on top . this created zebra stripes all over floor recreating rucking lines of paper .
Stangely the area covered by hardboard did not get affected but usually it would if moisture gets in to harboard the resin bleeds through and is impossible to remove.

I was not at fault as advised whAt should have been done but wanted to help main contractor who is a great builder and long term customer.
I really looked in to this problem and it was actually more complicated tah yours as I have found that dura limestone actually gets affected by oxidation and this naturally cahnged colour of stone.
but for this purpose for you, I have been in your position and i think it is redeemable.
I had experts that had poultices/experts at cleaning with best products/experts at steam clean. none of them worked .
the only thing that worked was repolishing stone floor. but this is not as simple as it seems .
there are various methods of doing this, dependent on what stone this is.
Some methods can create the orange peel effect and i tried a number of contractors before the solution was found .
Ironically they were no where near the most expensive but it is alll about experience with this type of problem.
I have restored stone for 20 years and I was well out of my zone.
Dont panic . I did and was envisaging a £ 50.000 dig up /replace for my contarctor and was so worried even though this was not my problem I wanted to sort for him.
we got result and just finished another very high end propery together.

can give you more info if nedd

Yeah sealed once because I had to get out so the next trade could come in. It was being sheeted over anyway and so would be protected. I was due to return to finish sealing when the stairs were in. I had no choice in the matter. Client had booked a time slot with the stair people and that was that. You know how it goes, client is always right! lol
Would more sealer of stopped this from happening? To me it looks like burn/steam marks. I've sanded a tile and the marks seem to run deep. The covering was down a good few weeks I think.

Thanks Jonny. Any extra info would be great!

I've been told by the client that its Moleanos white honed limestone. The other side to this is the stairs are fitted and come down onto the tiles. If they re-hone them how much do they take off? will there be any lippage? Can they get in close to the existing stairs/obstructions with the machines?

dont worry about only sealing once .
One mans one sealing coat might be equal to anothers 3 coats.
Some people seal once or twice after fixing when stone dry before grouting.
if you are worried you have not sealed enough, just take a look at your photos .
these stain marks do not correlate to lack of sealing alone.
the staining or rather lack of would be uniform if you had not sealed enough.
This is a moisture issue and covering problem.
I dont really know what general advice to give because every case is individual .

I just asked as i thought you meant you had finished totally...

Was there moisture still in the stone before they covered it..? from the grouting..

Just trying to make sure no blame comes back to you..

Thanks. I have been worried about it to be honest. Tiles were all dry and fine when I left. Client and contractor have agreed its nothing to do with me so I'm pretty clear of the mess I hope.
I'm just trying to fix this for the client and earn brownie points.

This problem is typical for me as a regular stone fixer in the end of market that i work in ,that requires a temporary floor covering for perhaps 6 months before completion. Every job we do is different.
We are dealing with a natural product , but this product differs hugely .
Gone are the days when fired earth delivered terracotta/slate tiles that were dry and could be presealed on the floor of a garage or outside before fixing.
Few stones come dry by dint of fact that they are cut from block and crated instantly.
We should adapt to every stone as they show themselves to us .
I fear that there seems to be a generalisation developing that all stone is the same and can be treated as such.
But as all we stone members know, we need to treat each stone with respect as they have more quirks than we ahve to offer.

This might ruffle a few feathers but, If the floor wasn't finished as in two coats applied for full protection then is there a chance that some of the problem is also the tilers fault