On 18/11/2017 11:49, Bert Coules wrote:
John Rumm wrote:

You might only get deflection of the tongue when there is force
applied...

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.

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

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

Chances are there is a dip either visible at the top of the UFH
panels, or under them such that they can push down a bit when loaded.

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.

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.


I wonder if laminate laid over UFH needs more expansion room than the
norm?

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.

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.




--
Cheers,

John.

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