upright and rafter spacing

[mqoh]

Framing my walls for my open air coop in Florida 12x6.7 with a four foot area walled part way up on three sides. I know to put the uprights 24 inches apart in the "coop/walled area but is 48 too far in the 8 foot run area? Should I pop two more in there to make it stronger? I have 48 inch hardware cloth and was thinking that just adding a few crossbars would be enough. Is 48 okay for metal roof support? And how far apart would you space rafters? My friend builds houses and his advice is way overkill. I know we have a bobcat in the area. Plan on attaching hardware with screws and washers. Thanks for your input.

 

[mowin]

For the few extra bucks, I'd do 24" OC. Will make the structure stronger and less "give" in the HC.

 

[3KillerBs]

We did ours as a post and beam structure with posts 8 feet apart and 2x4 uprights to serve as "nailing strips" for the hardware cloth.

Build thread here: https://www.backyardchickens.com/threads/large-open-air-coop-in-central-nc.1443812/

 

[mqoh]

For the few extra bucks, I'd do 24" OC. Will make the structure stronger and less "give" in the HC.

Yeah I tend to cut corners to save dollars but I know you are right just needed to hear it

 

[U_Stormcrow]

If you were nearby I’d bake you some cookies. Can’t tell you how much I appreciate your help

I was last in the Lutz area about late October. Drove to Tampa, met some friends, then headed to Fruitland Park for a weekend. Used to live in Temple Terrace, had looked at a hobby farm in Brandon about 15 years back.

Honestly, taking the time to say thank you is more than reward enough. Good luck with your build!

 

[3KillerBs]

I’m doing a double top plate because I want an overhang of at least 1 foot maybe 2

Generous overhangs are almost always highly desirable.

They keep the weather out of your vents, shade the walls, and protect you from the rain while you're collecting eggs, etc.

 

[U_Stormcrow]

Since there is no reason to build it like a people house, it only need be strong enough that you can carefully walk on it occasionally for maintenance, I use 2' on center, purlins spaced approx 24" oc - and I use 5/4 x 6 pt deck boards instead of 1x4 grade 2s for my purlins. Locally, they are cheaper, pressure treated (in case there should be a leak), wider (easier to hit with screws from the top), thicker (more thread grip), and much less likely to have a knot in them which renders it structurally useless.

Did I mention they are often cheaper?

Here are some pictures of one I threw together in a weekend. That's the goat shed. I did something similar with the bunny barn I just extended off the shed.

/edit Thickness of your rafter is based on Span. For my purposes, I'll take a 2x4 to almost 10' unsupported length (meaning a 2x4x12, to allow me 1' of overhang on each end (roughly). I weigh about 165# and of course we have no snow loads. 2x6 for anything of greater span. Whether that's sufficient safety margin for you or not?? I can't answer that. they do make span tables.

 

[U_Stormcrow]

oh, and you want your roofing screws to have approx 3 full thread penetrations thru your purlin - because basicall they ifrst three threads constitue the point of the screw and have no effective grip strength.

Into purlin vs Thru purlin is the difference between your roof peeling in a summer storm and a cat 1 'cane. In theory, the roof is stronger than that, but the same excellent ventilation we provide for our birds also means a lot of air can get under the roof and push upwards. Those tiny screws have limits - as does the thickness of the roof itself. More purlins plus more screws = greater resistance to wind uplift forces.

 

[mqoh]

Since there is no reason to build it like a people house, it only need be strong enough that you can carefully walk on it occasionally for maintenance, I use 2' on center, purlins spaced approx 24" oc - and I use 5/4 x 6 pt deck boards instead of 1x4 grade 2s for my purlins. Locally, they are cheaper, pressure treated (in case there should be a leak), wider (easier to hit with screws from the top), thicker (more thread grip), and much less likely to have a knot in them which renders it structurally useless.

Did I mention they are often cheaper?

Here are some pictures of one I threw together in a weekend. That's the goat shed. I did something similar with the bunny barn I just extended off the shed.

/edit Thickness of your rafter is based on Span. For my purposes, I'll take a 2x4 to almost 10' unsupported length (meaning a 2x4x12, to allow me 1' of overhang on each end (roughly). I weigh about 165# and of course we have no snow loads. 2x6 for anything of greater span. Whether that's sufficient safety margin for you or not?? I can't answer that. they do make span tables.

If you were nearby I’d bake you some cookies. Can’t tell you how much I appreciate your help

 

[mqoh]

I built mine with everything 24" OC with the rafters laid out directly over the studs with a single top plate on the wall. If your rafters and studs aren't going to work out like that on layout then I'd definitely say you need a double top plate on your wall.

You certainly don't want any walls 48" OC if you're planning on getting on the roof, and even if not I'd still advise against just from a stability standpoint.

Here's ours....



View attachment 3398937

Very nice. Thanks for the input. It makes a lot of sense. Last week I had never heard of a purlin. I am going to do everything 24oc. I’m doing a double top plate because I want an overhang of at least 1 foot maybe 2