[Post updated Dec. 2017] Most chicken coops are made of wood, and all wood eventually rots. Our coop designs feature overhanging roofs to protect the structures and their occupants from rain. But your coop will still get wet and be exposed to humidity, insects, and UV light. To protect the wood from the ravages of being outdoors you have a few options:
- Build with wood that’s infused with pesticides (pressure-treated)
- Use a naturally rot-resistant wood (like cedar, redwood, or tropical hardwoods)
- Choose a softwood (like Douglas fir, hemlock, spruce, or pine) and apply a nontoxic sealer or treatment
- Choose a plywood designed for exterior use and stain or paint it
In this post, I’ll go through each of these options, weighing the pros and cons. I’ll start with my least favorite and end with my preferred approaches. For a quick overview of our 10 tips and takeaways click here.
Anything that’s put into or onto wood may find its way into your chickens, then into you. So let’s first consider the reasons to avoid using pressure-treated (PT) lumber.
- PT can leach copper and other potentially harmful stuff into the soil where your chickens will be. I say “potentially” because the preservatives currently used in PT (alkaline copper quat, or ACQ) is said to be safer than the stuff they used to use (chromated copper arsenate, or CCA) in that it doesn’t contain arsenic. That said, the EPA still advises against using any kind of PT where the lumber contacts soil, crops, or livestock in an organic production area.
- PT requires more expensive fasteners designed to be used with ACQ, such as stainless steel or hot-dipped galvanized screws and nails. (Regular galvanized fasteners aren’t designed for the increased level of corrosion that comes from contact with copper. Read more here.)
- PT is softwood lumber injected with chemicals that render it pest-proof, maintenance free, and water resistant for many years.
- It may be cheaper than other wood types.
- Where it actually makes the most sense to use on a chicken coop is at the bottom of the frame, yet that is precisely where your hens will be scratching around and rubbing their beaks. Leaching of toxins can be minimized by priming and painting the lumber.
- If you prepare it right, treat cut edges, are careful in collecting sawdust, and use it appropriately, PT might make sense for you, especially if you’re in an unusually humid or termite-prone area.
Cedar, Redwood, and Tropical Hardwoods
If you’re wary of pressure-treated lumber, there are wood species that last a long time thanks to natural preservatives inherent in them. Cedar is the most widely available, though in certain regions redwood and tropical hardwoods are easier to come by.
- Using naturally rot-resistant woods, such as cedar, redwood, and tropical hardwoods gets you around the toxicity problem altogether. It is possible to use these products without sealants saving you time.
- Because of the demand for these woods, they can be pricey.
- Rot-resistance can vary from tree to tree. Also, while cedar is praised for its rot-resistance, this characteristic is true more of the heartwood than the sapwood. Most available cedar comes from second-generation forests and lacks the longevity of old-growth heartwood. You would have to seal it in this case, and if you’re sealing it anyway, you might as well use cheaper softwood.
- Sourcing heartwood cedar, redwood, and FSC-certified tropical hardwoods can be time consuming. You may be in for an expedition when looking for more specialized lumber products.
- Some people have concerns about the effects of the oil in the cedar on chickens. There is a lively, well-informed discussion in the comments below to help you learn more.
Softwood — Stained, Painted, or Preserved
This is my preferred option for lumber to frame up a chicken coop. Using standard softwood lumber (fir, spruce, hemlock, or pine) and sealing or treating it with a nontoxic paint, stain, sealer, or preservative takes a little more time, but it gets around the potential toxicity issue of pressure-treated lumber and is usually more affordable than a naturally rot-resistant option.
- By sealing/treating lumber with a nontoxic product, you can transform less expensive, off-the-shelf lumber into a long-lasting, weather resistant building material.
- My preference for preserving softwoods is TimberPro UV’s Internal Wood Stabilizer (IWS). It brushes on like water and reacts with the wood to harden and densify it. One application (2–3 coats) is all it takes. Wood treated with IWS stays bright for a year or two, then fades to a silver, naturally weathered patina. As of this post update in late 2017, our coop has lasted nearly a decade in rainy Portland, Oregon, where it gets soaked in the winter and baked in the summer. It has shown no signs of rot. Unlike with PT, standard fasteners still work with wood treated with IWS.
- If you prefer a splash of color, it’s possible to paint over the top of IWS as long as you wait the proper time to let it cure (at least 3 weeks — see manufacturer’s site). The manufacturer does not recommend staining over IWS, as the IWS seals the wood too well, preventing the stain from soaking in. You may, however, do a combo, staining the outward-facing sides of the boards while using IWS on the inner faces. Give extra attention to the bottom of the frame (the sole plate), all the cut ends, and any horizontal surfaces. Those are the areas that will be most exposed to moisture.
- Many coop owners prefer simply priming and painting and skipping the IWS application. Paint will protect the outer surface of the wood from the elements. But consider that wherever a nail, screw, or staple penetrates the wood, water can get in. So once you’ve attached hardware cloth to your frame, you won’t be able to retouch the paint — neatly, anyway. Choose paint and sealers carefully to avoid toxic ingredients.
- As for stains, I like the offerings from TimberPro UV. Osmo brand stains are really nice too. For more about stains and sealants, see our Buyer’s Guide.
- It takes time to apply any of the above treatments.
- If you plan on painting over IWS, you have to wait three weeks after you prime and paint.
- Nothing in IWS repels insects such as termites. But it’s worth remembering that chickens are voracious eaters of termites, and they forage down low, right where termites would be of concern.
- You can’t easily repaint lumber once hardware cloth has been applied.
Grades of lumber
A note about grades of lumber. Grades indicate relative appearance and strength. The higher the grade (smaller #), the better. Lumber stamped “#2 or better” or “standard & better” is the way to go.
Unseasoned or “green” lumber has a high moisture content, which makes it heavier, and water in the wood creates a poor surface for products like paint and stain to properly bond. Instead, look for two-by-fours that have been kiln-dried. The drier wood will also soak up more of any stain or treatment you apply.
Some portion of your henhouse may require plywood. As with dimensional lumber, there are different options depending what you need and how much you’re willing to spend:
- Oriented Strand Board (OSB) is the cheapest form of plywood. OSB is engineered by using adhesive and compressing layers of wood strands together to form a solid sheet. OSB that has been sealed with primer and paint is a reasonable choice for use inside the henhouse. Seal it well or cover with linoleum if you’re going to use it for the interior floor. Do not use OSB on exterior applications where it will come into regular contact with moisture. It will swell and fall apart.
- Keep in mind that regular exterior plywood is also not meant for use as siding. The glues in exterior plywood are formulated to stand up to temporary moisture, but they cannot withstand sustained exposure to the elements. If you are going to use regular plywood on the outside of the coop, protect it well with a primer and at least two coats of quality exterior latex paint or a sealer. Inside the henhouse, it’s just fine to use.
- Even better for siding is to choose a product intended for that use, such as T1-11. This typically has a textured surface on the outer face (rather than sanded or bare) that won’t split or blister as easily and holds up better to the elements.
- A truly rugged option inside and out is marine-grade plywood. This is designed with water-resistant adhesives and more durable wood. Marine-grade plywood is significantly more expensive and harder to find than standard, exterior grade plywood.
- Instead of marine-grade plywood, I prefer medium density overlay panels (MDO). Their smooth, resin-soaked veneers make them ideal for outdoor applications, and their smooth finish accepts paint very well. Importantly, it is cheaper than marine-grade plywood and can be used similarly.
Remember to paint all outer faces and edges of the walls and doors as well as the inner faces of any doors. You can paint the inside walls and floor of your coop too, if you want. I like white for this, and the glossier and more durable the finish the better.
- For framing and roofing use standard softwoods and apply a nontoxic paint, stain, or preservative such as TimberPro UV’s Internal Wood Stabilizer (IWS).
- If you prefer more color on your coop or are concerned about greying wood, wait three weeks after the IWS application and prime and paint your lumber.
- Sand, stain, prime/paint all plywood.
- For siding, use a product intended for use as siding. Avoid using OSB as siding and consider medium density overlay (MDO) panels instead of regular plywood.
- Remember that the best wood may be what you can reclaim from another project. Make sure it is free of lead/toxic paint, seal it up, and you’re good to go.
- For health and environmental concerns, steer clear of pressure-treated lumber unless you live in a very humid environment or have termites. Even then, use it only where needed.
- Remember that once you attach hardware cloth to your chicken coop, you will likely never get the chance to paint or seal the frame properly again.
- Build so that you can replace pieces without having to dismantle the whole coop. This way, a rotten board every few years isn’t such a big deal.
- Mix materials based on how exposed they’ll be in your finished product, investing in longer-lasting materials where it pays to do so.
- The perfect is the enemy of the good. Don’t let your search for the ideal materials or design get in the way of building something. After all, it’s just a chicken coop!
What has worked for you (or not) in your coops and outdoor wood structures? Please leave a comment below. And visit TheGardenCoop.com to learn more about our detailed chicken coop and run plans and hardware kits.