Roof truss question

[Zebedeewesty]

I'm gonna be building the trusses for my garage.
They will be of the king post type like this with a 4/12 pitch. Building regs won't let me have them any steeper as then the ridge would be higher than allowed.

Would 2x6s be OK for the tie beam and king post with 2x4s for the rafters? Or do i need 2x6s for those aswell?

The span is only 10ft and the roofing will be corrugated steel with an anti drip (condensation) lining which is pretty light.
We don't get much snow on the coast either.

 

[Jhoff310]

Yes 2x6s for the tie beam will be fine with 2x4 king post...unless your local building code says otherwise.

Jeff

 

[Gone2Far]

I have been designing trusses for over ten years and maybe once have used a 2x6 web. Ten foot span you should have no worries. If you want you could run to your local truss plant and have them run one truss through their engineering program to see if you can use smaller lumber than 2x6 and save some money.

 

[gpflepsen]

10' span? I'd drop the king post.

 

[Kevin54]

If it is only a 10' span, all you need are your trusses and a ridge beam with nothing underneath at all except for maybe two ties from wall to wall.

 

[joe_padavano]

If it is only a 10' span, all you need are your trusses and a ridge beam with nothing underneath at all except for maybe two ties from wall to wall.

At which point they aren't trusses, they're just rafters.

 

[gpflepsen]

The point is, the king post offers no structural benefit to this design, and actually just adds more weight and cost.

The only reason to keep it is if you would be hanging a point load that the 2x6 tie joist can't support.

How long is the ridge line? If it's not too long, use a ridge beam and just have the rafters form a vaulted ceiling. No tie joist to even consider then.

 

[Kevin54]

At which point they aren't trusses, they're just rafters.

Very true and a mistake on my part by calling them other than what they truly are.

 

[Zebedeewesty]

Garage is 20 foot long.
If i was to just build the trusses (without the king post) could i just tie them together with purlins instead of a ridge beam?

The original roof trusses were all angle steel with wood purlins similar to this one:

 

[Kevin54]

usually you set your ridge beam first, then you have something to fasten each rafter to. Your purlins are going to give you something to fasten your sheet metal to. If you have a ridge beam, you will already have your rafters stabilized as far as front to back movement. Your bottom chord will keep your walls from bowing out.

As I take it, you are only 10' wide and 20' long, so each rafter is going to be roughly 6+ feet/side, correct? This is including a 1' overhang. At a 4/12 pitch, using a ridge beam, the length of each rafter is 6' 4 3/4" using a 2x6. My shed is 12' wide and they used 2x4 rafters and it has never sagged.

Check out this site http://www.deplans.com/plans/gardenShed/tenFooter.php

Now go here http://www.deplans.com/plans/ And on the far left you will see where it says "Download Garden Shed Version 1.0.0.3". Click on that and another window will open up where it has a small folder that says "Garden Shed" Open it up and you will see this.......

This will let you input all of your sizes. Then when you click on "DRAW PLAN" it will give you a list as to what you need and the dimensions to cut everything to beforehand.

This is what you will see after you click on "DRAW PLAN".....

This should be able to walk you through everything you need as far as getting your building framed up. If you have any questions about it, let me know and I can walk you through it as I have played around on the program quite a bit.

BTW......the "Component" button you will see just gives you a detailed larger drawing of your rafter cuts along with the "birdsmouth" cut that you would have to do.

 

[Zebedeewesty]

Cheers.