My chicken coops have always had metal roofs, and now I’m trying out metal siding, on the grounds that I want anything I build to last 20 years without maintenance, and the exterior plywood I’ve been using doesn’t deliver that.
[Update: Seven years after writing this blog post, the corrugated metal walls are holding up well. Seven years is long enough for plywood walls to start falling to pieces, but the metal walls are holding up well, with only a bit of rust here and there.]
Does Metal Promote Condensation and Wetness?
People will tell you that metal siding sweats, because of condensation. This is true if the inside of the house is warmer than the outside, since moisture from the warm house will condense on the cold walls and ceiling. But it’s not about metal vs. wood, since condensation forms on any kind of roof or wall, no matter what it’s made of. In marginal cases, it’s more visible on metal because it’s 100% non-absorbent.
A Fresh-Air House is a Dry House
But you can dodge the problem with a fresh-air poultry house. If you add enough ventilation, the inside of the house is just as cold as the outside, and you get no condensation. My metal roofs don’t have condensation unless there’s snow on the roof and temperatures are above freezing. The rest of the time, my highly ventilated houses have dry ceilings and walls.
This is one of the main points of Fresh-Air Poultry Houses, the chicken-coop book I’ve republished (check out the sample chapter if you haven’t already). It focuses on the advantage of well-ventilated houses, a concept that still needs to be repeated constantly today. You won’t read anything about metal walls or roofs in this book, since it predates their use, but it’s a treasure trove in other ways.
You can also prevent condensation with insulation, but I don’t do that.
Can you really prevent damp chicken houses through ventilation alone? Well, it works for me, and I live in Oregon, which has a famously wet climate!
Installing Corrugated Sheet Metal Walls
Back to the construction project. In keeping with my other rule of construction (never use a saw when you can buy stuff that’s already the right size), I ignored my existing stock of 10-foot metal roofing and obtained some cheap 8-foot corrugated roofing from Home Depot. My chicken houses are 8×8 feet.
Karen and I banged these sheets onto a couple of sides of a chicken house where the old OSB siding was falling to pieces. We used roofing screws. These are hex drive screws with neoprene washers. We used to use roofing nails, but they pull loose too easily and we hate having roofing panels flapping loose in the breeze! And using power tools instead of a hammer keeps my shoulders and back from seizing up. I bang the screw in a short way with a hammer, then drive it home with a cordless drill.
I’m told that roofing screws have three times the holding power of nails.
These panels went on very quickly, and if they ever rust through (which they will, at the bottom edges anyway, if I allow chicken manure to pile up against them), I can take the screws out and replace them just as easily.
So far, so good. The shiny metal really brightens up the interior of the chicken house, and because it’s non-porous, it provides no place for roost mites to accumulate.
Cheap Roofing is Good Enough
Plain old “ripple metal” (corrugated steel) is less rigid than V-channel roofing, but it’s proven to be stiff enough, even for a house that gets dragged around behind a tractor, which can put all sorts of stresses on it, especially if it gets hung up on holes and bumps along the way. So far, so good. That means that, so far, the cheapest possible corrugated metal has been perfectly adequate.
Watch out for translucent corrugated fiberglass. In my experience, it’s not very strong and becomes increasingly brittle over time. I’m sure it has its uses, but don’t think of it as being structural in the way that plywood and corrugated steel are.
You Don’t Have to Settle for Ugly
Of course, you can build a much prettier house with metal roofing with baked-enamel finishes in designer colors, and you should probably do this if you don’t want a silver house, since it’s hard to get paint to stick to galvanized steel. While I’m always looking for the cheapest, longest-lasting, easiest-to-build designs, there are plenty of other ways of approaching the problem of chicken-coop design.