wrote:

Oooer John , the roof has been up for over 35 years so clearly the
joists are enough for current use. I have checked and there are 2

They will be "enough" but I would not risk putting much load on them!

lateral 6x2 runninng across the width of the roof space (5.2m). There

Right - that will help a little.

If I put a long beam across the garage (5.2m), at 90 degrees to current
4x2 joists, what size beam/rsj is required. (I would prefer wood is it
can be strong enough). Then can I put additional 6x 2 above and meet
the deflection requirements. (I would leave the 4x2 in place to save
work).

5.2 is going to be too long for wood or flitch beam - given that it will
be carrying some 26 joist ends if my sums are right... (at about 1.3 kN
per joist end)


Alternatively what would be the effect of 1 x rsj below the 4x2, then
additional 6x2 lateral beams on top of the existing 4x2 (90 degrees to
current joists) ? Not sure of the engineering effect, but very easy to
do.

You could do a RSJ below (perpendicular to, and at the mid span) the
4x2" and then new 8x2" or something poarallel to the 4x2"s but
interspaed between them.

--
Cheers,

John.

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