Can I Topcoat Log Siding with Polyurethane?

I would like to have your take on using oil-based polyurethane on exterior log siding. I have made a test on a piece of log siding (pine) and left it out on the ground face up for the last two years and so far it has weathered quite well. I am in northern Maine where the temperatures are extreme and very wet at times. Any comment(s) would be appreciated for using it on my log siding home, for or against it. – Frank

Chris Marshall: Sounds like your experiment is proving its own answer for you, Frank. If you feel the amount of weathering that’s happened is within your expectations after two years, maybe poly is the right choice. I’m surprised that it’s worked as well as it has in your test, because typically the “go-to” varnish for exterior applications is spar varnish. It offers better UV protection and stays more flexible as the wood expands and contracts to keep water from penetrating. I would be concerned about how you’ll “refinish” the siding when the poly wears out — and of course, eventually it will. If it peels, you might have to remove it all to get back to a suitable surface for a fresh re-coat. Maybe other eZine readers have given oil-based poly a try as a siding topcoat too? How about other options for a clear, long-lasting exterior wood finish that’s also easy to maintain? If you have a product type to recommend to Frank, please share your opinions!

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