PT lumber


In the Brooder
5 Years
Sep 19, 2014
Mass, USA
I'm designing a Lean-To style coop and run that will be covered with a metal roof that over hands about a foot on each side.

Besides the footings and verticals on the walls where do should I use PT lumber and where can I use the less expensive non-PT lumber?

Would you recommend using PT lumber in the coop if I leave the studs open on the inside of the coop?
I use PT on any wood touching the ground or concrete. Also anywhere that is likely to be in frequent contact with water.

You won't need it in the eves/rafters if the roof has adequate overhang and is water tight.

Some worry about it being toxic to chickens, but chickens don't eat 2X4s.

Simple contact with the wood shouldn't be an issue. Painting it will form a barrier if you are worried.

If the wood is new and fresh, it needs several months to dry out from treatment so the paint will stick well.

Recycled PT wood will have far fewer problems, if any really exist.
Modern PT lumber is not a hazard to the birds, the warning you see are for the old-style lumber treated with arsenic or petroleum-based preservatives. So, you can use it everywhere, but it is more expensive and heavier. Anything in contact with moisture should be PT. If it touches the ground, or any masonary like concrete or cinder blocks (wicks water from below), it should definitely be PT.

Flooring is also prone to getting wet with water the chickens spill or manure. Wet manure will rot wood very fast, protect your flooring with a watertight barrier or use PT plywood (or both).

I avoid PT lumber for roosts and feeders, not that I don't trust the PT chemicals, just rather not have them there.
I live in the Northeastern US so it isn't unexpected to see a foot of snow on the ground so the verticals will have to be PT. It isn't so much about the chemicals as it is about the price difference.

I plan on attempting the deep litter method for the coop because I have a piece of very thick rubber membrane to protect the flooring.

so looking at this very crude picture red being PT and black being Non-PT do you think this is the right type of lumber for each part of the coop

As said by others, any wood in contact with the ground should be pressure treated. But anything above grade does not need to be. A simple coat of paint will preserve any wood above grade - that's how houses are built, so it will certainly work for a coop. Your vertical posts do not need to be PT, but I would paint them.
If the wood is new and fresh, it needs several months to dry out from treatment so the paint will stick well.
I've been told that this isn't true of the newer PT, and that letting it dry before painting will just cause more cracking/splitting.

People need to be careful and make sure they know which type of wood they're talking about - the newer stuff is very different than the older stuff (CCA)
Perfect. This answers my question of safe use of PT lumber. But has anyone considered using PT privacy fencing for sides of coop? Just nail it to 4x4s and leaving tops open a bit with hardware cloth meeting roofline for ventilation is my idea. Cut windows and doors ,etc. Anyone think this is doable?

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