Use metal conduit instead of lumber to frame light-weight metal roof?

[Mother of Chaos]

Morning, everybody (or afternoon or evening, depending on where you are)! The thread title is pretty much my question.

Background:
When we were building the chicken run, my husband objected to the look of the 8' high posts, thinking it would look too tall and looming. (We have a pretty small city backyard.) So it's 7' tall, next to but not attached to an old wooden shed.

Our three girls (three months old now!!) are living there pretty happily, but I'm planning an eventual roof. The footprint of the run is 8'x15', and I want a shed roof (not with the triangle gable ends, but just slopes in one direction, back to front in this case.) There's no way to have an overhang that is useful if it sits directly on the 7' high studs. Grrr.

So, I'm envisioning a triangular base that sits atop the existing lumber framing of the run, with the slope of the triangle allowing for the proper slope (rise/run) for metal roofing.

This is beginning to sound like a lot of heavy lumber. Can metal conduit be used, and if so, how do we attach the roofing to the conduit? I'm having trouble visualizing this.

PS: we do not typically get heavy snow load in these parts these days, but of course, who knows any more.

Pic from the construction days (there's a bit more there now, lol; also fewer random flower pots):

 

[Mother of Chaos]

I was hoping to catch @aart's attention here, because I value her experience and her sense of design, but she's been off BYC for a while, it appears.

In case it helps, here is a mutilated sketch of what I'm thinking of.

Anyone here use conduit as a structural material?

 

[Island Coppers]

ChaosMom​

One of the advantages of metal roofing is that it's rigid enough to not require much support. So, lowest part of the roof directly on your frame, highest part on a rectangular box using the frame as the bottom, uprights to the height needed and one cross piece with support midway between the front and back. I would use wood perhaps 2'x3's rather than conduit because they're easier to work with.

 

[Mother of Chaos]

ChaosMom​

One of the advantages of metal roofing is that it's rigid enough to not require much support. So, lowest part of the roof directly on your frame, highest part on a rectangular box using the frame as the bottom, uprights to the height needed and one cross piece with support midway between the front and back. I would use wood perhaps 2'x3's rather than conduit because they're easier to work with.

* blink blink * That's perfect! I didn't think I could get away with such a minimal structure. And thanks for the description - very easy to visualize how it would look!

The distance to span is longer than 8', and I don't want to pay the much higher cost per foot for longer panels. Is that one crosspiece with support in the middle the logical place to overlap them?

 

[Island Coppers]

Is that one crosspiece with support in the middle the logical place to overlap them?

Yes, overlap them as much as you can and perhaps add a support, front to back right at the overlap. *Not guaranteed against a large snow load.

 

[perkolator]

While I think it could technically work, wood would be a better material to support the roof. Conduit will bend/sag along their length, which definitely won't help with any roof loads like snow. You can build a roof structure with minimal lumber - my metal roof is supported by 2x4s spaced 24", and perpendicular 1x4 purlins spaced about 24" - but I have zero snow to be concerned with. Personally I would spring for the longer roof panels so you get less splash-back coming into the run. I'd also put a gutter or something to keep the water from that shed roof from just spilling into the run.

 

[Mother of Chaos]

You must be a mind-reader! I had pretty well thought to this point. I'm glad you mentioned the purloin spacing, because I was clueless on that.

And as it turns out, it was plastic corrugated panels that I remembered were so expensive. 12' metal wasn't as bad. Thanks!

 

[perkolator]

Yes, the two roof materials are fairly close in pricing, so I'd get metal - it lasts longer. Just make sure you orient your support structure perpendicular to the corrugations - lately I've been seeing a lot of coops online where people barely support their roof, and the supports are going parallel to the corrugations

 

[Mother of Chaos]

…Just make sure you orient your support structure perpendicular to the corrugations - lately I've been seeing a lot of coops online where people barely support their roof, and the supports are going parallel to the corrugations

That’s… interesting!

I favor having the corrugations running downhill,myself. Did they not have purloins?

 

[perkolator]

That’s… interesting!

I favor having the corrugations running downhill,myself. Did they not have purloins?

Yep, no purlins giving perpendicular support for the corrugated panels, and their 2x4 rafters were oriented the flat way!