Garage Roof Joists

[Carl1973]

Hi all,

I am currently in the planning phase of a brick (self build) garage. The dimensions are 14 x 24 ft. I am curious what size roof joists i would use across a 14 ft span, I figure 6x2's but maybe 10x2's and then cutting the angle for drainage using a table saw, I figure this to be about 3" with a 1/60 drop.

Would seem to be a bt easier cutting down the one joist as opposed to cutting the angled joist (wedge shape over length of joist) and nailing onto a 6x2 but so far am not fully decided.

Thanks

 

[theoldun]

Say 4300 span.
Access for maintenance and repair only Dead load, 0.50KN.m2. Imposed load 0.75KN/m2, will require C16 47x200 regulised down to 195mm, at 400 centres.
Firings on top either 75 down to 5m, or 70 down to zero. for 1 in 60 fall.
Regards oldun

 

[joinerjohn]

Yep, as the old un says, firring strips fixed on top of the joists will give you the required fall. No need to have the joists cut to make the fall.

 

[Carl1973]

So 2x4's would be the order of the day then..

Answered 1 question...

I didn't know what the slanty bits are called.. Firings (every days a school day), means I can hopefully get some 2x3's and rip them on the diagonal to make 2 firings out of each bit of timber and save wastage.

Cheers theoldun, and thanks for the confirmation joinerjohn, answers now stored on "puter" for future reference..

 

[joinerjohn]

I think you'll find that 195mm are nearer 8" than 4" joists. The slanty bits are called firrings. Much easier to purchase these from a timber merchants than cut down 3" lengths ,diagonally.

 

[Carl1973]

Joinerjohn,

I concur, was having a mathematical moment (or lack of).. was just about to edit my post, will have a word with my timber merchant and see if they do the firrings etc... have a few good ones near by.

Update - They sell them, happy days.