John Rumm wrote:
Steve wrote:

Thanks for that Tony. I will download the demo and have a play with
various options.

I just did a quick calc in SB with a 1.3m 4x2" beam. Assuming a uniform
floor load of 0.8kN per joist, plus a worst case point load in the
middle of the span of 1.6kN (i.e. one piano leg), your current floor
fails to meet the spec in bending and deflection - but not by a huge
margin. Doubling up the exiting joists with another the same size sat
beside it (and nailed too it would probably be simplest at that size),
seems to make it stiff enough.


Thanks very much for that John.

I have downloaded the software from Tony's website and had a quick play.
But it is clear that I need to follow the advice on there and print
out the instructions! It does seem a very nice piece of software that
has the potential to teach me a lot more apart from this question... but
I need to learn how to drive it! Also I was very impressed that the only
feature 'nobbled' in the demo was the ability to print out the results -
fair enough. Nice not to have a time limited demo with lots of features
disabled as so many are.

So thanks also to Tony for generously making the software available to
non professionals like myself.

Coming back to the joists, I had a gut feeling that deflection would be
more than desired and your results back this up although you have quite
rightly taken the worst case with the load in the centre of the span. In
our case most of the load will be near to a sleeper wall for each leg.
But I would rather be conservative and use worst case!

One idea was to double the joists up i.e. putting extra joists in
between but in the areas of high load to have double joists joined, but
I had thought of glueing them together and bolting through the neutral
access. Any problems with glueing and bolting?

I also had an extension to this idea...I thought of cutting 8" strips of
18mm WBP, glueing two together and then sandwiching that between two
joists, all glued and bolted. In effect a 'T' beam. Obviously the ply
can't extend the total length because of the sleeper walls but that
would probably not matter as shear is unlikely to be a problem, I think.
Any comments on this idea?

Cheers

Steve