In article , David in
Normandy writes
Someone has asked me to help put in an upper floor in a farm
outbuilding. The room dimensions are 7 metres by 5 metres constructed
with a single thickness of breeze blocks. He is planning having 7 metre
long joists and fixing down traditional tongue and groove floorboards on
top.

Is this feasible? 7 metres sounds like a very long span unsupported,
assuming that you can even get 7 metre long joists? I would have thought
that at least one cross beam would be needed for such a span.

I'm happy to lay floorboards and do the associated DIY but I'm no
structural engineer!

Suggestions?

Might be a job for engineered joists but even then 5m sounds better than
7m which I suspect could get a bit expensive and bouncy.

This came up on a quick search (engineered joist span):
http://www.trussform.co.uk/
Useful data here on spans and rigidity:
http://www.trussform.co.uk/download/...ical_Guide.pdf
Note plenty of options at about 5m diminishing towards 7m.

Not local to you of course but I'm sure there will be outfits in France
too.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********