I have a small two-step 2 deck that comes off my sunroom, and due to the location, the deck never gets any sunlight so it's almost perpetually damp/wet during rainy spring and summer, making it the perfect place for a carpenter ant colony.

The sunroom itself is supported by short pressure treated 6x6 posts going onto concrete bases, and these get damp from time to time if the rain is heavy enough.

I plan on replacing the ant-infested deck with composite decking, but since the stringers will be made of wood, they are just as susceptible. There is also an exposed wood face as the final step up to the sliding door of the sunroom that is perpetually damp.

Aside from the composite boarding on the horizontal surfaces, how can I protect the other wood surfaces from carpenter ant infestations?

  • 2
    Colonize the wood with plumber ants. They don't get along. (Don't get me started on electrician ants.)
    – bib
    Commented Jun 26, 2015 at 12:46

2 Answers 2


Pressure-treated lumber, or one of the tropical hardwoods which develops its own insecticides, should be proof against both termites and carpenter ants for many years.

Outside of that, catch and fix rot early, since carpenter ants are most likely to move into wood that has already suffered some damage.


As keshlam mentioned, always start with pressure treated lumber. Beyond that keep it sealed/stained every year, it doesn't sound like you will have much wood left once you replace with the composite so it should be pretty easy.

This helps prevent rot and splitting and can keep insects away. It will also help prevent things growing in and on the wood.

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