markk

iTrader: (2)

Ive had a materials list handed to me for my garage project for the roof,

now, I think it looks like this guy is planning to build a fookin arc on top of my garage with how much timber he's asking for, steel I can work with, timber I fookin hate.

So, lets spec a roof,

the building, 10m x 8m, the pitch is 1.5m from the eaves height, the materials are going to be marley modern concrete tiles, I have three fooking massive girders in the roof, one at the ridge and one on each side half way down, so these are going to support the most weight, not that its going to be that heavy compared to a conventional house size which would just use wooden purlins.

RSJ's are 203 x 133 x 30's.

so what size timers would we use for the rafters on the whole?

I dont want anyone going over board "just to be safe" I want the correct calculations for the right size.

Im sick to death of being told to over spec something on this job when its not needed.

cheers
mark

Lee Reynolds

Is that 8m front to back with the roof rafters going front to back also? That is a low pitch, without the drawings or anythng id guess at around 22deg?

I agree with using girders as the purlins on that span, but why at the ridge i dont know...doesnt need it.

markk

iTrader: (2)

yes Lee, that is front to back, the 10 meter is the width, and yes the pitch is low (feckin council regs), I have no actual drawings for the roof.

for what ive been priced in just timber alone, I could buy steel for the job and make the whole roof frame in steel never mind fookin timber !

Lee Reynolds

What timbers has the builder specced? At around 22 deg, with steel purlins you can use 100x50's at 400mm centres, with a 200x25 ridge board. Really no need for that ridge girder imo.
What about the ceiling joists? As you wont span 8m in one go, is he not installing a central girder to carry the ceiling joists?

markk

iTrader: (2)

he has specced a variation of 150x50's, 100x50's, 150x75's and 50x25's, and a lot of them.

We dont need a ceiling, so nothing needs to span the 8m, though I have put pillars in incase i decide to put steelwork in.

I have maintained I want the roof space open and free so I can do what I want with it.

CraigoScott

iTrader: (1)

off topic and sorry I cant help with the roof, but what length are your RSJ's and how much you paying for them, as I have had some of the same size specced to me today and need a ballpark figure? Cheers,

Lee Reynolds

Ah right, i then retract my statement over the ridge girder, as it will need this as you are not having ceiling joists to stop the spread of the walls with the load weight of the roof, so the roof needs to rely on being held up by its own structure and not rely on the down force of triangulation spread. I'd also say that i'd go 150x50 as the main rafters so that a good birds mouth cut, about a third depth, can be achieved onto the purlin beams to help stop spread.

Are the purlin girders/beams being sat on padstones and bolted down?

The Youth.

iTrader: (1)

lee you are talking goboldigook to a non builder like myself!! lol
I do find it fascinating that you can roll off the sort of calcs you are without seeing anything!
should a nice big work area when finished mark,

steve

Lee Reynolds

Lol it all breaks down into standard practice Really Steve! Most jobs are the same just on different scales
Tbh i thought i'd put it accross easy to understand?

markk

iTrader: (2)

9.750m long and just over £150 each

Cheers Lee, and yes, padstone ar going intomorrow and RSJ's bolted in

Lee Reynolds

Any progress pics Mark?

markk

iTrader: (2)

its a bit dark out at the moment, its about a course off to roof level, not bad for two lads in just over two weeks.

i'll update the other thread tomorrow.