span

[kchill78]

what is the reccomended size joist for a 5 meter span

[harryagain]

If you are talking about a floor, ie lots of joists side by side.

In imperial, the rules of thumb is:- depth of joist in inches = half the span in feet+2

So half of 16' is eight plus two =10" deep. (ie 50mm x 250mm) Assuming 2" joists @ 16" centres.

For domestic loads only.

It will need two rows of braces to prevent disortion. Joist offcuts, timber herringbone or metal strutting. Last can be bought and is easiest by far.

Might be more convenient to have an RSJ down the middle and smaller joists cut into it @ rt angles.

[John Rumm]

Depends on what loading you are sticking on it...

A quick set of calcs in Superbeam suggest:

For a normal floor with a uniformly distributed load of 0.8 kN/m on the joist, long term load configured for load sharing (i.e. more than 4 joists in total), you would need a 50x220 timber with a C24 spec.

If you want to use C16 timber, then you would need a 75x220 timber to meet building regs specs.

[Capitol]

The timber dimensions are specified in the building regulations, or at least they are in my very old copy! John's figures are pretty similar, but you may be able to get away with 50 x 200 if using SS timber and the loading is low enough. Harry's suggestion of an RSJ may well be the easiest solution, 203 x 133 seems about right for a span of 6M.

[John Rumm]

Another option if you want to get the height down is a flitch beam...

[harryagain]

Oh and use metal joist hangers, don't build into the wall. Much better/quicker/easier solution.

[paddygreen007]

snip

Never heard them called that before. I usually think of them as laminated or engineered beams.

Was just thinking about making up a ramp for loading a lawn mower into a trailer and was considering making one up out of something like this.

A flitch to me is a side of bacon !

[John Rumm]

;-)

Flitch seems to be a fairly common term for a pair of wood beams bolted side by side with a thin steel plate between them. However they may well be regional variations.

Picture of the end of one with a 8mm plate here:

[Tim Watts]

For a long time I kept calling them "filtch beams"

[John Rumm]

The cheaper version?