Hope someone out there can help me with this one. I’m building a house and its a weekend project, so to save some money, I decided to use metal joists and rafters instead of engineered lumber (TJI) type. The metal was less than 1/2 the price (1.10 vs 2.50 per ft) so it seemed like a good idea at the time, and it went pretty smoothly with the floor joists (although they don’t feel quite as nice as the wood “I’s” under foot).
Here’s the problem, I’m now framing the roof and I have two large dog house dormers to frame. Has anyone out there ever framed a dog house dormer with metal studs and rafters. Due to the climates in our area, the roof rafters are 12″ So I’m looking at making compound Miters through 12″ metal rafters in the valleys . The problem is that the channels that they typically frame into are a fixed dimension (12″) so they won’t accept the mitered ends at the valley. The backing cuts on the valley jacks that I have always spent most of a day figuring out and cutting when framing a dormer with wood can’t be cut into metal. etc, etc, etc. If some one feels that they have some good experience here and wants to help, I will be glad to detail each problem for you to address.
Otherwise, If anyone can refer me to a prescriptive method for framing a dog house dormer with metal, that might help. The prescriptive methods book that I have (from USS) does not have these details.
Thanks in advance for any help that you can offer.
Peter
Replies
Perhaps you can cut the rafter, say 12" longer then needed, then, on the "cut line"( as if it were a piece of wood) bend, instead of cut, to an angle in line with the other member, and join with several bolts/ screws. You may have to cut some of the channel to do this.
Red,
Thanks for your suggestion. I had thought of that and I actually tried soemthing like it around the stair openings on the second floor. Basically frame the thing like you whould do a door opening if you were framing with metal stud and channel. The problem is that were talking about 16 Ga x 12" deep joists here. They dont bend that easily, and when they do bend they don't make a nice sharp straight corner like lighter gauge metal. Also, you can't really cut them with a snips. The only way to cut this stuff is with an abrasive blade in a cut off machine, or with a torch.
Even if you could bend the metal along the cut line, it would leave the bent end sicking out above or below the roof. Also you would end up cutting the channels at every rafter. It would be a lot of work, weaken the channel and proabably not come out so good anyway.
I've been thinking a lot about ways to do this and my solution seems to be to frame the valleys with wood.
Thanks again
Peter
Perhaps you can cut the rafter, say 12" longer then needed, then, on the "cut line"( as if it were a piece of wood) bend, instead of cut, to an angle in line with the other member, and join with several bolts/ screws. You may have to cut some of the channel to do this.
didn't think so (bend) easy, thought I'd suggest it anyway.
plan "b" ..... attach together with clip. lousy angle, I presume, not something you can get at Home Depot, maybe your supplier can order from a mill. or....
plan "c"...... get a mobile welder on site, have him fabricate clips/ hangars/ gussets/ whatever.
or.. plan "d" . use wood as you mentioned, problem solved.
Thanks
For making the cuts, you need to use a 4 1/2" grinder with a fine cut-off wheel. They are about 1/8" thick or less and will cut 16 ga. material with ease. As far as attaching the members together, we use 110v mig welders to make the connections.