Building coop with metal roof...use purlins or osb decking?

[whitenack]

Building an 8x8 chicken coop/shed and plan to roof it with some extra sheets of roofing metal I have leftover from an old barn project. I already have enough 7/16" osb sheets on site, but I don't see anyone using that for metal roofs. I assume it is best to use purlins instead of osb?

 

[U_Stormcrow]

Purlins. Because its cheaper, and it lets you see the underside when the inevitable leak eventually develops.

HOWEVER!!! If you have OSB already, its no longer cheaper to use purlins (and you can't cut OSB into strips, it doesn't have the same strength). You can use OSB, and secure your metal to it, same as is done in a people house. its overkill, but its not wrong. In your specific circumstances, its cheaper.

 

[Ted Brown]

Ditto the above.

You did not say where you live? Bare metal in colder climates can cause humidity to condense and drip into your coop, not a good idea.

 

[Chicken Chow Man]

You want to talk about overkill...living in northern MA/NH border, for my 4 x 10 low pitch shed roof i put 3/4" plywood down, covered that with grace ice & weather shield. On top of that i laid some 2" foam insulation (because i had it laying around) and on top of that used my old steel swimming pool wall.

The 2" foam gave a nice gap so that i could put a cheap vent in the high point of the shed roof which is still covered by the outer most steel.

I had no issues whatsoever with condensation but we also had a relatively mild winter this past year.

I would imagine in much colder climtes (numerous successive days of below zero temps) condensation becomes a bigger problem.

 

[EggSighted4Life]

I already have enough 7/16" osb sheets on site

The OSB might be good enough insulation to stop the condensation dripping.. but it does NOT have to be a "cold" climate as mine is considerd "moderate" with average lows around 40-45 F and highs between 50-60.. Very very cold mornings here are 32, and very hot days are 75. Any cold enough morning (which is most of them) when the sun shines on the roof and heats up.. let the indoor rain begin!

No amount of ventilation by itself will prevent this.. my covered runs and patio that are fully ventilated on at least 3 sides still drip.

If the sun doesn't shine on, such as rainy days.. no condensation or dripping.

My pole barn was in place when we bought this house. I know plenty of commercial building have metal roofs without issues.. proper installation makes a huge difference.

Hope you build goes great!

 

[5Australorpasaures]

I sheathed with 1/2" OSB #15 felt then metal. I didn't want to waste time screening the voids and went full soffit venting. More money but less custom fitting.
.

 

[whitenack]

Thanks all. I'm in Central KY, so I get a little bit of every kind of weather. Very humid here, so condensation is a bit of a concern. Maybe I should do a little insulation too.

 

[aart]

I'm in Central KY

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[mowin]

I sheathed with 1/2" OSB #15 felt then metal. I didn't want to waste time screening the voids and went full soffit venting. More money but less custom fitting.
.

This^. It's a pain making the metal roofing predator proof if you don't use sheathing underneath.

 

[whitenack]

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Thanks!