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

[NameIwish]

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?

If you're using 'new metal' the OSB would be wasteful IMHO. I used 1x4 purlins 24" OC in both my metal roofing projects and OSB or Plywood Sheathing for my shingle roofed projects.

Years gone by - no complaints or issues with the metal. Chickens don't need much in the way of shelter.

 

[NameIwish]

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.

Which is another good reason to pitch your metal so it runs down hill and out.
It is a Chicken Coop - birds roost in trees in the wind and the rain and even in the snow a little condensate's not going to bother them at all. We have bird the choose to roost in the peach tree even tough the coop is open long after they've gone to roost.

 

[NameIwish]

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

What predators are you proofing against? Curious, actually. Knock on wood (not the roof) I don't think we've ever had a predator in one of our coops. We've always had at least one dog and a doggy door that never closes! (flaps, of course. - home made with shower pan liner flaps - cheap, flexible and durable)

 

[mowin]

What predators are you proofing against? Curious, actually. Knock on wood (not the roof) I don't think we've ever had a predator in one of our coops. We've always had at least one dog and a doggy door that never closes! (flaps, of course. - home made with shower pan liner flaps - cheap, flexible and durable)

Mice, rats, weasels can easily squeeze through.

 

[3KillerBs]

What predators are you proofing against? Curious, actually.

Snakes and Least Weasels can get through remarkably small holes.

Also mice.

 

[avjudge]

Snakes and Least Weasels can get through remarkably small holes.

Also mice.

Assuming you are talking about the holes created by the roof‘s profile as the ridges pass over the bottommost purlin (or second from the bottom if your ceiling to the wall): A closing strip for your brand of roofing (so it properly matches the profile) should allow it to be sealed as well as any roofing material. This might be more difficult with salvaged material, if the profile can’t be matched, but if it’s a current popular brand that should be easy to find.

I’ll try to get pictures of my polycarbonate aviary roof to show the sealing — different material but similar issue.

 

[3KillerBs]

Assuming you are talking about the holes created by the roof‘s profile as the ridges pass over the bottommost purlin (or second from the bottom if your ceiling to the wall): A closing strip for your brand of roofing (so it properly matches the profile) should allow it to be sealed as well as any roofing material. This might be more difficult with salvaged material, if the profile can’t be matched, but if it’s a current popular brand that should be easy to find.

I’ll try to get pictures of my polycarbonate aviary roof to show the sealing — different material but similar issue.

The metal profile I used didn't leave significant holes, but some profiles do.

 

[LuciferRoo]

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

Why?
I am about to start building a new coup and plan on using metal roof without sheathing.
Maybe I am not anticipating something but I don't foresee any issues with predator proofing.

 

[3KillerBs]

Why?
I am about to start building a new coup and plan on using metal roof without sheathing.
Maybe I am not anticipating something but I don't foresee any issues with predator proofing.

It depends on the profile of the metal.

There are ones with deep corrugations that leave openings large enough for smaller predators to wiggle through and there are ones that leave only the smallest of gaps.

 

[avjudge]

Eek, I see I posted about 6 weeks ago about how closing strips allowed me to seal my aviary’s polycarbonate roofing that has the same profile issue, and promised pictures - and then completely forgot about it. Rather than try to remember again, I went through my photos and found a few that may work to illustrate.

Here you can barely see the ends of the strips on top of the two lowest purlins. Predator proofing is to the 2nd purlin. Since it’s an aviary I don’t need to provide soffit ventilation so it’s all solid construction there.

(If this were a solid structure and I wanted soffit ventilation I’d skip the second purlin and either put hardware cloth from the bottom of the fascia back to the outer header, or wrap from the purlin down around to the header without a fascia board.)

I took this picture to show 2 of my pigeons, but you can see a bit of the closing strip on top of the 2nd purlin (and the blocking - the wood between the rafters - that goes from the purlin to the outer header so the entire structure is solid.

This last picture was to show the setup for my chickens that spring, but the aviary is in the foreground. Here the closing strip/bottom purlin/fascia make a solid seal with no voids. In my structure thus is purely for aesthetics but in a different structure it could be the predator-proof layer.