Callum wrote:

I think probably the best course of action will be to install the 6x2s
in between the 3x2s and attach them to the walls with hangers. Would I
require an inspection from the builder officer for this, even though it
matches with the rest of the room (and the house come to think of it).

The trickey bit is that it will need to comply with current building
regs. The old floor may not meet them. There would be no need to bring
the old floor up to spec, howevfer the new one would have to meet the
spec. Hence if calculations show that you actually need deeper beams to
keep the deflection under the required limits you may have a matching
problem!

Though to be on the safe side I'll probably be looking in the yellow
pages for a structural engineer tomorrow!

You could have a play with the demo version of superbeam:

http://www.sda.co.uk/sbw.htm

and see what sort of answers you get first - that may give you a good
indication of how difficult it is likely to be.

(You can just model one beam to start with - enter the dimensions, and a
uniform load of say 0.8kN/m, turn on "load sharing", and see what
happens. If you are having difficulty getting in spec then you can
experiment with wider beams, better timber (i.e. C24 instead fo C16), or
even flitch beams (i.e. with steel plates in them).


--
Cheers,

John.

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