Can anyone recommend a good treatment to prolong the life of cedar fence posts? I’m specifically interested in applying something to the part of the post buried below ground.
Also, anyone got advice on whether or not to set the posts in concrete, gravel, or just dirt?
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Replies
I'd suggest green Cuprinol #10 http://www.sherwin-williams.com/apps/PickPros/SWDisplay.asp?ProdID=521 .......... any Sherwin Williams store should have it. If it were me, I'd treat the entire post but at least treat it to a point somewhere above grade level. Most wood posts fail right at ground level. The green color (it's from the copper fungicide) will fade in a matter of months. I wouldn't use concrete- it traps water around the post. At the the fence company I worked for many, many years ago we used well tamped crushed stone (for drainage) followed by topsoil and that's what I still use for my own work.
Thanks JC - great advice. Please clarify a couple of things for me.
1. are you talking about finely crushed stone like the stuff that's used as patio underlayment?
2. can I stain over the Cuprinol witha solid white stain?
3. can I treat the posts and set them quickly or do I need to let the Cuprinol dry for a long time?
1
It needs to be a well draining soil that can compact and stay there. Inch minus works good
2
It might take a couple coats or seal over it with a shelac based sealer first, like Kilz or BIN
Another treatment option is injection with Borate treatment and wrapping the post base in plastic to keep oxygen out. Not as toxic and it is pretty clear.
3
Dip and sink..
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It may bleed through. If you're using an oil/alkyd stain to topcoat, they recommend one thin coat of Cuprinol followed by 24 hours of drying time. For latex/acrylic stains, they recommend waiting 6 to 12 months. A link to their data sheet................ http://www.sherwin-williams.com/apps/PickPros/display.asp?type=data&id=521
If you're going to stain, I'd shy away from treating the whole post. Most wood preservatives use paraffin as a water repellent and the waxy surface will hurt the stain's absorbtion/adhesion. You can mask off the area you want to treat to provide a break between the stain and the wood preservative. You can set the posts in a pail or tub filled with a couple of inches of Cuprinol- the end grain will really soak it up. Two coats and you can set them right away- a little messy tho'. 3/4" or less stone or gravel will work fine. The important thing is to tamp it in small lifts (layers) and not fill all or most of the hole and try to do it all at once.