Damaged laminate flooring over underfloor heating

[Bert Coules]

In fact I wasn't testing the right area. The board that shifted wasn't damaged at all: it's the adjacent board. Though its tongue appeared intact, one length of it is completely separated: it's held in place by the still-attached tongue either side of it which is why I didn't immediately notice it.

So a second plank has to come up, I think - a rather less daunting process now I've dome a previous one.

Another discovery this morning: there's no deflection at all in the UFH panel but one area of the flooring isn't laying flat against it. With the t&g intact it wasn't particularly noticeable but once one plank was freed to move independently downwards it became immediately apparent.

I wonder if laminate laid over UFH needs more expansion room than the norm? If that's the case, and if the fitters didn't leave enough space against the walls, then the problem becomes a bigger one, given that the L-shaped kitchen units are masking all the edges.

[Bert Coules]

Actually it was the right hand edge. But see my post a minute or so ago in answer to John Rumm for more details.

[John Rumm]

I had a feeling that might be the case...

Which kind of suggests the UFH is just following the (uneven) sub floor its sat on. Packing out under the new laminate boards in the low spots should fix it.

As long as it has some it should be ok. The total movement is not going to be much in absolute terms unless the floor area is huge.

[Tim Lamb]

Yes.

Can you see if the other end of the flooring is tight to the skirting/wall? It might be easier to adjust there than struggle under the units.

[Bert Coules]

Thanks for the thought, but unfortunately the other edges are under skirting. However, with a mirror, a stick and some undignified lying full-length on the floor, I've been able to establish that there's a good space on at least one of the kitchen walls. The other is hidden behind plumbing.

[Bert Coules]

John, thanks for that. A bit of experimentation has revealed that judicious packing does seem to eliminate the movement. The problem now is that the replacement plank, even with its t&g edging trimmed on three sides, doesn't want to go back into the space left by the old one, general movement over the whole floor being to blame, I suspect.

[John Rumm]

They are usually a fairly tight fit, so you may need to tap it into place with a block and a hammer.

[Bert Coules]

For fairly tight read impossible, and for tap it into place read shave a (very small) bit off one long edge. Fixing the deflection deprived the plank of its original full-width, non-flat-lying home, I think.

And now the job is done, everything is back in place and the floor doesn't flex beneath my feet any more. Many thanks to everyone who chipped in with ideas, thoughts and suggestions: all much appreciated.

There's still movement elsewhere in the area, caused I reckon by the un-flatness of the underlying floorboards; I wouldn't be entirely surprised if another t&g join were to fail some time in the future. But I'll be ready for it next time...