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I recently installed a tongue-and-groove floating bamboo floor over a concrete subfloor and almost immediately it began making an unbearable cracking sound whenever I put my foot on it. I used PVA glue to glue the boards. The concrete subfloor curves gently over a length of about 7 metres (with the height of the curves in the middle of the room) but there is no other significant unveenness. I also used a cheap 3mm all-in-one damp-proof underlay from B&Q.

Is there any way of addressing this short of pulling the floor up?

If I need to pull the floor up what is the best way of doing so to avoid damage?

When relaying the floor is there a better type of glue I can use or other precaution I can take?

Thanks for any help.

It's unlikely you'll be able to take it up without damaging the boards, how bad is the unevenness?...You might have to live with it, but maybe someone else can suggest a cure.

this is just an observation... you walk on it, you hear a crack - does the same area crack again when you walk on it again?

Just thinking that I laid an engineered wood T&G floor which had to be glued and also used thin foam underlay. I got a few cracks in selected places on that but it settled down very quickly and was fine after that.

maybe have a good old walk around it and see what happens

heeellloooo pete 1982 and welcome

have you left an expansion gap all round without pinch points !!!

you should have an expansion gap at the minimum required on the fitting instructions

Yes I did leave an expansion gap of around 1 inch all around - I just checked for 'pinch points' (places where the floor touches something immovable?) and there are none.

The cracking occurs everywhere - uniformly all over the floor - not a specific point - and to the same degree.

We left it for six months and it hasn't settled down.

The unevenness in the subfloor isn't noticeable when you walk on it at all. It's very gradual and there is no unevenness over any 2m length.

Any help on my original questions?

The cracking you can hear is the glue cracking in the joint. After time the glue will eventually come apart then the boards will work lose and you will end up with gaps in the boards.

The underlay you used may be causing this as it may be too soft to support the boards. I prefer to use floor levellers from floors 2 go.
Or your subfloor floor is too uneven, no more than 8mm over 1 meter for the tolerance usually.
Another posibility is that the boards have cupped. Run you hand across the width or lay a straight edge on the board. This would cause the glue to crack.
To take your floor up probably would not damage the boards but you would have to tediously clean the glue fromn the joints which could take days. If the joints are not cleaned out properly the boards will not go back together properly.

It was partially my suspicion that the underlay is too soft - it felt like the floor was depressing underneath my foot.

When I put weights evenly all over the floor then (a) the cracking disappears and (b) the floor feels 'firmer' to walk on.

As for subfloor evenness - I am pretty sure the floor is not as uneven as you say - but it does bow upwards slightly over about 7 metres.

Can anyone help me on point 3 - when I reglue, should I use a stronger /different glue. A friend laid a floor over a very uneven subfloor using a glue called STICKS LIKE SH*T (not a joke) and says he's had no problems...!

i am afraid the chances are are negligible that you will get the floor apart unless the glue is of a realy poor quality or off batch even then it will only "break" in some areas and not in others

Hi
I have good experienced in fitting floor and something that im starting to specialise in.
The most common problem that people cause is by fixking solid flooring using the floating method. I wouldn't reccomend this unless it was engineered flooring.
First of all you have used pva which isn't the correct glue to use on a floating floor. PVA glue on solid floors dry like glass hense the cracking noise. This is the glue cracking and crumbling as you apply pressure by walking on it. Has it not expanded yet and started to rise? It will if it hasn't already.
One of the more tempormental flooring is bamboo, so since u have used the floating floor method there is nothing that you can do since you have a concrete sub floor.
As suggested before when you pull this foor up it will come in a way where some are separate planks and other area will come up as a complete section. I am trying to find a company who will cut planks down e.g. 130mm wide boards to a 120mm board with new tongue and grove so it can be fixed correctly. Since this is such a common problem. I get on average 10 calls a month asking to sort flooring out which has been the same way as you have