How flexible is flexible grout?

Hi,
My downstairs neighbours took down a wall that had become loadbearing 5 years ago, splitting my first floor stone kitchen floor from side to side as the beams it was holding up re-settled. An insurance claim followed and repair work completed, with over-loaded beams hung off other beams with face fixed hangers and others having new timbers bolted along-side them, for strength (the beams are a bit of a dogs dinner after the house was converted into 2 flats in the 60s - virtually no beams go wall-to-wall).
I re-laid my stone floor, instructing my builders to use flexible grout. I saw the bags of grout, and the flexible mastic, but 4 years later, my stone floor has split again in exactly the same place (I never saw a single crack in the 15 years before the load-bearing wall came down).
My neighbours' surveyor who recommended the patching up of the beams and told me to use flexible grout upstairs recently looked at my floor and told me that as he couldn't get a thumbnail into the grout, it wasn't flexible. I would have assumed that even flexible grout would cure and harden? Is that right, please? Is flexible grout actually soft? It isn't like latex sealant, right? Is there a way I can tell if the grout is flexible or not? I'm happy to lift tiles. MANY THANKS

Don't know how to tell if grout is flexible or not but would imagine it is designed to flex with changes in temperature rather than movement. Did the bags you saw have the words flexible on them anywhere?
If the floor has cracked along the same seam then its clear the original repairs were not up to standard.
Not much point in strengthening the original beams if you cannot re-lay a decent hard wearing floor on them.

Thanks for the quick reply, conny. Appreciated.
Yes, the bags I saw were Weber 'Joint wide flex' and I checked with the supplier last week - as I still have the delivery note - and they apparently only sell flexible grout. The only option is that my builders bought and had flexible grout in the house, but used different grout on the job. I rate this as very unlikely as I have known my builders for years.
To my mind, the repairs to the beams downstairs were not adequate if there is enough movement for the whole lot to split again.
The surveyor who orchestrated the repairs is blaming my split floor on the grout though. Very frustrating as I don't know how to prove this one way or the other! From what he was saying, flexible grout should be soft to allow physical movement (I presume new wood bolted to old wood would have different expansion and contraction rates, setting up stresses), and he was adamant that as the grout between my stone tiles (big tiles, about 2' long) was too hard for him to get his thumb nail into, I hadn't followed his instructions. I don't feel confident replacing them for a second time in case the same thing happens again.

Hi Joanne, please forgive me if I am wrong but I am assuming by your username you are indeed a lady?

How a surveyor can try to tell you that your grout has caused your floor to split is beyond me, (Unless you are blonde and he has a biased view of blondes). Its clear that the original repair was not up to standard. You make a very valid point about new timber bolted to seasoned timber having different expansion rates and, as you seem to be quite intelligent, I would suggest you write the surveyor a letter stating that you have taken advice on this matter and these are your suspicions. Also state that you would like a free written report of his findings and that when you receive it you will be seeking further advice based upon what he has said in the report. (Basically, turn the screws on him to prove he is right in what he says, not for you to disprove it). As I am not a builder I could not confirm what the problem may have been that caused this but you certainly seem to be on the right track

Hi,
Yes I am a girl I did ask this surveyor to put his findings in writing, which he duly did. He genuinely seems to believe that my grouting isn't flexible, which means my floor is one big solid sheet on top of a floor that is now more flexible since that load-bearing wall came down, making it "inevitable" that more damage would occur. I'm just not sure he's right about that! I expected the repairs to give me a solid floor to work with again, and I certainly don't seem to have that.
Am hoping a builder will be able to answer my question about grout hardness definitively, but thanks for the support. Appreciated.
J

I once used "flexible grout" and it was exactly the same as normal grout, so far as I could see.

Cracked all the same in due time too, due to weak floorboards.

Flexible grout will set rock hard, and will only cope with miniscule movement, It certainly won't stop cracking from say, a dodgy beam..

Ask the surveyor what his specification is for flexible grout, then email the company of the grout you've used to see if this complies with the surveyors recommendation, then take it from there !

As 'middleagedun' has stated, flexible grout is not a miracle product and is not a panacea for unsuitable floors, merely that it will absorb a bit of seasonal change or moisture content changes in timber products.

If your floor flexes or bounces then it will crack.

Often a ceramic tiled floor is simply not suitable for certain scenarios.

The time and effort I spent upgrading my suspended timber kitchen floor in order to have a trouble free tiled floor was considerable but worth it.

Forget speaking to the grout people, it's not the grout at fault and you'd get a cop-out response in any case.

Hi,
Thank you sooooo much to all of you for taking the time to reply. Very kind of you.
So it looks as if my neighbours' surveyor telling me that flexible grout would have stopped my floor cracking despite the beams (minus that load-bearing wall) now apparently flexing more than they used to was a red herring. The grout itself has not cracked, by the way (it's in immaculate condition), only my lovely stone tiles have split.
Surely a surveyor would know that flexible grout sets hard (?) - which makes me think he's not playing this entirely straight. He has also put in writing that the spitting could be because the stone tiles were laid straight onto the beams (they weren't - there is plywood there), because any plywood might be floating (it's screwed down) and because my builders didn't use a 'levelling screed' to check the floor was flat, which I thought was used for a concrete floor, not a wooden one?! Any thoughts on that one, please? My floor now has a 'low point' in it (confirmed by my trusty glass marble 'spirit level') that I am 100% certain was not there a few years ago. There is a slight, but none-the-less evident, sensation of walking downhill in my kitchen!! I had presumed the surveyor was responsible for restoring the strength of my floor back to what it was before that downstairs wall was taken down. Instead, I have been given what feels like excuses for why damage has recurred, and no solution to it occurring again.
I am pretty upset that because my neighbours took down a wall (without telling me they were going to do so) it sounds like I can't have a stone floor any more without suspending it. I had a beautiful floor for the 15 years before they did this work. I presume suspending a floor is expensive.......