upright and rafter spacing

[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!

 

[Raptor Chicken]

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....

 

[Raptor Chicken]

ETA- As far as the roof goes I used 1x4's for the purlins on a tin roof, which is pretty standard. If you're using a poly roof regardless of what you use for purlins you're not going to be getting on top of it. Just a FYI.

 

[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

 

[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.

 

[Raptor Chicken]

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

Thats a good plan but the overhang has nothing to do with needing a double top plate.

If the studs for your walls layout with the rafters you don't need a double TP. The reason for a double TP is for the possibility of a rafter falling in between studs on your wall. Proper planning can prevent this.

We have about a foot overhang on our coop that I showed above.

 

[mqoh]

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

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.

Stormcrow, Do I need to add a fascia board and drip edge to the high side of a lean to roof. I'm not worried about the low side as I plan to leave it open like your picture.

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.

Do I need to finish the high end of a lean to roof with a fascia board and drip edge. I plan on leaving the bottom open like your picture above.

 

[Egghead_Jr]

I love your roof and I’m going to do a take on it. I’ll send you a pic when I get done. But how many rafters do I need. Structure is 12 feet with a one foot overhang on each end. Every 2 ft would be 9 is 2 feet overkill or right

It's not about the load the roof will support it's about holding the roof down so it doesn't sail away in a wind storm. With strapping that's secured well to the rafters and the rafters extremely secured and the posts anchored down you'll be fine. Without load, Florida, the rafters and posts can be any spacing you want. The connections have to be secure all the way to the ground anchor system- concrete in sona tubes?

Being in Florida you should not be surprised what a good wind can do. Then think about a roof with no walls to stop the wind, it's a big strong sail that can tear your structure apart if the connections are weak.

 

[U_Stormcrow]

Stormcrow, Do I need to add a fascia board and drip edge to the high side of a lean to roof. I'm not worried about the low side as I plan to leave it open like your picture.

Do I need to finish the high end of a lean to roof with a fascia board and drip edge. I plan on leaving the bottom open like your picture above.

yes, I would fascia and drip edge the high side as insurance against windblown rains and as small deterrent against direct intrusion during high wind events.

 

[3KillerBs]

Being in Florida you should not be surprised what a good wind can do. Then think about a roof with no walls to stop the wind, it's a big strong sail that can tear your structure apart if the connections are weak.

IMO, if strong storms are a possibility then hurricane ties are not optional.