? Interior Varnish on Covered Exterior Door??

[Patrick McCarthy]

Hello all,

I am installing 3 new exterior doors with a doug fir veneer. All are exterior doors but 2 are covered by a breezeway connecting the back door to the shop, and the 3rd is between the shop and garage so it is technically an interior door but neither shop nor garage are heated nor conditioned.

I understand that spar varnish is considered exterior and is softer, but this is California along the coast with the lowest temperatures in the 30's and the highest in the upper 80's and sometimes maybe mid 90's but darn few of those.

Since there is no direct sun exposure and unlikely any rain on the doors, would i be better using a non spar, but oil based, varnish . . .which i understand is generally harder and easier to refresh??

Similar question with the next project : the front door with an extended porch such that only bottom would ever get wet and then only with blowing rain, and minimal direct sun only early on summer mornings?

Again, thank you for your willingness to share your experience and wisdom, Patrick

[Todd Burch]

Along the coast, I would definitely go with the exterior varnish - California gets no exemptions! ;)

[Patrick McCarthy]

Todd, thank you for your input, but given its relative lack of exposure what would be the downside to using regular or non-spar varnish? Would lacquer be tougher?

[Todd Burch]

I suspect UV inhibitors would be missing, and the salt-air certainly would be tough on it.

Perhaps, do a test. Use spar on one and non-spar on another. ;)

Or, call the manufacturer's help line and ask them what they would recommend, and why.

[Howard Acheson]

Even in indirect sunlight, there is lots of UV. The appropriate finish would be a non-poly exterior rated marine varnish. Polyurethane is rapidly attacked by UV and will quickly become cloudy, turn yellow and then crack and peel. Go to a marine supply store and look for brands like Interlux, Pettit and, best of all, Epifanes. Good marine varnish is expensive. Follow the directions on the label as to surface preparation and number of coats.

[Scott Holmes]

As usual, I agree whole-heartedly with Howie on this application.

[Patrick McCarthy]

Howie and Scott, thank you very much; marine it shall be!