On Jan 13, 8:08*am, harry wrote:
On Jan 13, 1:23*am, NT wrote:

On Jan 12, 2:54*pm, "Man at B&Q" wrote:

On Jan 12, 7:36*am, harry wrote:

I have seen plenty of excessively notched out joists (even from one
end of a room to another) but never seen one actually break as a
result.
The floor just becomes springy.
The cure being to bolt doublers on the sides with glue and/or timber
connectors.
Timber floors are massively over engineered. *They are sized to
prevent excessive deflection rather than actual failure as is a lot of
building material.
I wouldn't have thought that 20mm off a single joist would make a lot
of differerence.

You can saw a joist in 2 and no-ones going anywhere. You just get a
patch where its a bit bouncy.

And it's an old property, probably even more over engineered as they
didn't have the skills to cut everything to the bone like we do today..

MBQ

Actually joists on Victorian properties are way smaller and weaker
than modern houses. Its normally a complete non-issue in practice.

NT

They had better wood in them days than we have but otherwise exactly
so.

Yes. BR today are excessively tight on permitted sag, with Victorian
ceilings routinely grossly violating the pointlessly tight 3mm figure
(IIRC). Modern ceilings rely largely on stiff wood to limit sound
passage, whereas victorian ceilings relied much more on thick heavy
plaster to stop noise.


NT