preserving inside of a cedar window box.

[joe milana]

Any ideas on how to preserve the inside of a cedar window box? I have read about copper napthenate but dont know where to get it. Also not sure if it would harm anything planted in the box or even do any good long term. The local sherwin williams dealer suggested painting the inside with roofing tar. Someone else suggested "pond liner", but what about drain holes.

-Joe

[Dell Littlefield]

I built one once and sprayed auto body undercoat on the inside. It lasted for years. No effect on the flowers that I could determine.

[Rick Thom]

Any ideas on how to preserve the inside of a cedar window box? I have read about copper napthenate but dont know where to get it. Also not sure if it would harm anything planted in the box or even do any good long term. The local sherwin williams dealer suggested painting the inside with roofing tar. Someone else suggested "pond liner", but what about drain holes.

-Joe
Maybe drill a few drain holes and paint the inside with several coats of Thompson's Waterseal or the equivalent.
and/or put your plants in pots inside the box,
or buy a liner which is readily available at most garden centers or stores that sell garden supplies.

[joe milana]

Don't think thompsons would hold up under direct soil contact.

[Jim Nardi]

I'd make a liner out of galvanized steel. Or head out and buy a plastic liner before you build.

[Kelly C. Hanna]

Leave metal out of the picture for sure....it will trap moisture underneath and rot the wood [seen this many times]. I drilled holes in the bottom and coated the inside with spar urethane. The holes were big enough for copper pipe so that the drain holes went through the railing. Flowers every year since the build did fine.

http://www.hannawoodworks.com/pergolafinished.jpg

[joe milana]

I agree with the concept of moisture trap with any sort of liner. Spar varnish was suggested by another paint store but I wasn't sure it would hold up "subsoil".

[Kelly C. Hanna]

Yeah I kinda cheated.....7 coats and all were very heavy. I am sure it will break down someday but so far we have 4 years under our belts.

[Mike Running]

Copper Naphthenate and Zinc Naphthenate are both available at the borgs. The sell it for treating fence posts (which it isn't really good for). Woodlife and Gibson Holman are two of the manufacturers. The copper version is greenish and the zinc version is basically clear.

[Dewey Torres]

Joe,
Let's not forget that cedar is going to last for a very very long time, even with no protection. That being said, go the cheap and easy rout by lining the inside with visqueen from your local BORG. Use a staple gun to fix it in place and drill your drain holes in the bottom. Should last as long as any would expect a window box.