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Discussion Starter · #1 ·
Hi! I’m building a chicken coop/run, sized 10’x15’. I plan on building a 3/12 pitch gable roof, with the ridge running longwise, with metal roofing sheets. My question is about common rafters…what size boards will I need? Will 2x4, with bird’s mouth cut, 24” OC be ok (boy I hope so).
I’ll also put straps perpendicular to the rafters… the metal will me screwed to those.

I’d appreciate your advice!
Plant Wood Tree Home fencing Fence
 

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So the rafters will span 10’ , sure 2x4 will work .
you will need a few ceiling beams on top of the walls to hold the span .
A 16’ ridge board would sag over time and push your walls out in the center .
 

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Discussion Starter · #3 ·
So the rafters will span 10’ , sure 2x4 will work .
you will need a few ceiling beams on top of the walls to hold the span .
A 16’ ridge board would sag over time and push your walls out in the center .
Thanks for your reply! Are ceiling beams the same thing as a “collar tie”? (This is my first time building a structure— I’m learning as I go).
 

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collar ties could work allso , but a 2x4 rafter can flex in the center and would not be as strong
as 2 or3 2x4x10‘ going across from wall to wall holding the span .
A collar tie is set at 1/3rd down so 3on 12 Would be 5” from top of colar tie to top of rafter .
It looks like you have 8’ hight in the pic so you may not really need the extra height the Collar tie would give .
im sure the chickens won’t mined either way
 

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Go to your local library and you should be able to find a book that will show you how to properly build the rafters or roof trusses.
You really need to see some drawings, hard to explain in verbal typed format.
 

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what is your snow load ?

I wouldn't go longer than 6 feet unsupported with 2x4

here is a calculator


and span info
 

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Discussion Starter · #8 ·
what is your snow load ?

I wouldn't go longer than 6 feet unsupported with 2x4

here is a calculator


and span info
It actually never snows where I live.
 

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If you are running a peak down the Center (and not a single slope shed roof), the length of each rafter is only 5 feet. A 2x4 is plenty with no snow load. I don’t think you need ceiling beams with no snow load, although I might upgrade the ridge beam to 2x6. I think collar ties would be more than sufficient,
 

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Discussion Starter · #11 ·
If you are running a peak down the Center (and not a single slope shed roof), the length of each rafter is only 5 feet. A 2x4 is plenty with no snow load. I don’t think you need ceiling beams with no snow load, although I might upgrade the ridge beam to 2x6. I think collar ties would be more than sufficient,
Thank you- yes it’ll be two slopes coming down from a 2x6 ridge beam.
 

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what are you using for perlins ? 1x4 or 2x4

you said steel roof perlins and steel or are you going to deck it , tar paper it then steel ?

is heat and issue , a 1/2 inch foam board over your perlins and under your steel keeps the inside temp down considerably

the under side of bare steel cooks a building i have measured 144*f n a sunny day underside of a shed roof with an ambient temp of 86*f just can't move enough air to make the shed not hot the next building over has insulation not a lot and a decent ridge vent and it is only a little above ambient

the bare roof shed has 3 big power vents in the roof and 4 big barn fans it has 2 big overhead doors at one end and double walk doors at the other on 3 sides even all open with a barn fan in each walk door you cook in there it is about 140x80

the smaller building with the insulation has 2 overhead doors one at each end and no fans or power vents it is about 60x36
 

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Discussion Starter · #13 ·
Thank you for the note about heat— the building will be in light shade, but my area dies get very hot. I’ll look into insulating panels!
 

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the more overhang the better also

my parents house was about 400 yards from my grandparents house same siding , built a few years apart

mom and dads house needed painting twice as often as grandma and grandpas

the difference grandma and grandpa built their house with big eves 3-4 foot while mom and dads house 16 inches
grandma and grandpa also had a hip roof while mom and dad had a gable roof the gable end faced south and it needed to be scraped and painted more often that the rest of the house

their siding just got 1/2 the sun mom and dads did so it lasted longer

they even used the same brand in similar shades mom and dads house light grey and grandma and grandpas house beige
 

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Thanks for your reply! Are ceiling beams the same thing as a “collar tie”? (This is my first time building a structure— I’m learning as I go).
A rafter tie is in the bottom 1/3rd of the rafter, so a ceiling beam is a rafter tie. A collar tie is in the top 1/3rd, and much less ridged than a rafter tie.

In most cases I would do rafter ties/ceiling beams and no ridge beam.
 
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