Metal roof rafters

[Greg in RI]

Well, I've finished my oven!

Now I?m ready to build the enclosure. I plan to use 4? wide block and ?? Hardy Backerboard for the side walls and pitch the roof using metal rafters. Coat the vertical walls with Quikwall colored red and maybe experiment with some decorative tile, although I?ve been warned about the freezing cracking them. I have reclaimed roof slate for the roof which I?ll wire to hat channel using no sheathing.

My problem is coming up with the layout for the rafters. I have searched the FB site and the web and haven't found any instructions on using metal studs to make rafters. I live in RI and worry about heavy wet snow buckling a metal stud (even 2 together, making a solid beam). I?ve thought of using some stops between the rafters and some metal plates used for wooden truss fabrication. Has anyone come across instructions on how to build rafters from metal studs? Each half of my pitched roof will be about 5?x7?. I guess I could use wood but I?d prefer not to.

I posted my question yesterday to a thread started by Jaronimo last year with two gracious replies by Gulf and Tscarborough. I thought I would re-post and see if traction goes up.

Any thoughts?

Thank you,

Greg in RI

[Tscarborough]

Re: Metal roof rafters

What will the pitch be?

[Ken524]

Re: Metal roof rafters

Hi Greg,

I used steel studs to make trusses for my metal roof. I'm very happy with the strength and shape (7/12 pitch). We get an occasional heavy snow here in Louisville and I've never thought twice about the structural integrity.

Here's my thread: http://www.fornobravo.com/forum/f21/...sure-3002.html

Roof pics on pages 1, 2 & 5.
Warning: I'm an amateur. I made up my design as I went.

[vtsteve]

Re: Metal roof rafters

If your sidewalls rise above the dome, you could use kingpost trusses (that's what I did, using 18 ga. studs at a 6/12 pitch). If your dome goes above the sidewalls, use a ridge & rafters. Make the ridge as a box, using a stud nested into a track, then use a short vertical piece of stud as a clip angle between the ridge and the plumb-cut rafter end.

I built a prototype truss with 24 ga. studs, then laid it on a sheet of plywood and screwed down blocks against it to make a jig. Then I used the jig to make half a dozen trusses in 18 ga. structural grade. The short vertical pieces near the rafter tails bear on the sidewalls, to keep the stud web from collapsing under the point load; you can run these past the bottom chord, cut the flanges flush, and bend the extra web into a hold-down.

The bottom chord has the flanges trimmed so the web can lap the rafters; the rafters are lapped at the top - just cut away as much flange as required. Do *not* cut the flanges on the rafters anywhere else, or you will *severely* compromise their strength! Even this 24 ga. version easily bears my full weight.

[Greg in RI]

Re: Metal roof rafters

Way cool! Thanks for the instruction. I plan to mess around with metal studs this weekend. I've never used but I think I'm a quick study and believe I have all the right tools.

Thank you.

Greg

[Greg in RI]

Re: Metal roof rafters

My pitch is going to be 8:12 to accommodate a 3" head lap needed for my slate roof. This translates to about 35 degrees which will be easy to accomplish when I build the walls. I will have to add 12" to my terracotta chimney but I will make the joint just below the roof line.

Ken, thank you so much for the link to your site. What a wealth of information! I think I'm off and running now with what I need. My only fear is that I'll change my mind on something as I go along. I know already I need to adjust the placement of my walls to accommodate the access I made for the wiring.

Thanks again everyone.

Greg

[PizzaIdiot]

Re: Metal roof rafters

I used steel studs for the walls, but wound up using wood for the roof joists. I just didn't feel comfortable with the Home Depot steel studs for the roof joists. Since I'm in South Carolina and it's only a 6' span or so, I used 2x4s on 14" centers. I topped this 3/4" plywood
Think it will be a metal roof. I like your idea for slate.