In message , John
Rumm writes
On 16/11/2017 18:55, Bert Coules wrote:
Well, after some stop-and-go cutting with the plunge saw I've managed to
remove the suspect plank (and without flooding the kitchen):

http://bertcoules.co.uk/non%20websit...%20removed.jpg

(Short version: https://tinyurl.com/y9ytyasp )

My initial reaction was that I was surprised to see those particular UFH
housing-boards: I expected to find the ones for straight pipe runs,
which would surely give slightly more support. Of course I don't know
what's happening at either side of the exposed section: I suppose the
pipes might well be turning back on themselves there. You can see that
the pipework runs in two different directions and the two runs at the
bottom of the image do indeed turn through 180 degrees so the layout
isn't as straightforward as I would have thought.

The next thing I noticed - annoyingly - is that the plank I removed, the
one which dropped when weight was put on it - doesn't have a damaged
edge. And bafflingly, neither does the one next to it. Not only can I
see no reason why the depression was happening, I can't see *how* it was
happening.

More investigation tomorrow...

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

If you get a long straight edge, you should be able to see if there is
a low spot somewhere there.

If the problem was the left hand edge in your picture, the board has
less support there because it coincides with a pipe run.
Now you have it exposed, I wonder if some sheet aluminium could be
inserted as additional support.


--
Tim Lamb