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Treatment of exterior timber frame posts?

Cherilyn's picture

I am building a hybrid timber frame home, which will feature some exterior posts and beams for entry and porches, as well as interior timber frame portions. I am not as worried about finishes for the interior, as there are quite a few choices that will likely work quite well, but the exterior finishes I have had trouble with in the past.

I have used Sikkens Cetol 1 and 23 formulations for exterior timber frame posts and beams and found that this works quite well for up to about 5 years, and then it begins to peel and discolor with mildew and exposure to the sun. I have stripped these posts, sanding meticulously and reapplying both formulations carefully in the recommended conditions but find that the finish does not last long and needs to be refinished often.

Has anyone found a better product to use in this type of situation?  I am thinking of using a penetrating oil finish for the interior millwork and wonder if one designed with UV inhibitors would be appropriate for exterior use......Any advice on the experience of others would be appreciated.

"Log Oil" might work (post #187841, reply #1 of 5)

We use Duckback's Superdeck Log Oil on exposed exterior woods, such as shingles, decking and railings.  It is a penetrating oil finish available in several colors, and it can be tinted.  We actually manage to get it tinted a dark enough green to match the forest green trim paint we use.  So, it can probably be tinted to just about any color you desire.

Log Oil suggestion (post #187841, reply #3 of 5)

What length of time would the Log Oil typically last before reapplication?  Is sanding needed prior to reapplication or do you know?

Thanks for the suggestion. I have been looking into a product called Penofin which has UV inhibitors and is tintable so am curious about penetrating oil finishes.

My exterior DF 2nd floor deck (post #187841, reply #2 of 5)

My exterior DF 2nd floor deck of rough sawn 2x10s is open to weather (PNW rain and temp)and is going on 40 years, and still good shape except for a few spots that were sapwood.

I simply gave them 2 brush coats of 20/80 preservative mix, then stain, and has only needed one reapplication about 10 years ago.


OOPs, forgot to say I'd used penta, cant get that anymore I hear<G>  Only got a 5 gal can of concentrate left myself!

Have some posts in the ground I soaked in creosote - oops, cnat get that anymore either .....<:(>

Guess you'll just have to let the exposed stuff rot.....?   Honestly, have not found anything anywhere near as good as Penta was

Exterior DF deck (post #187841, reply #4 of 5)

Thanks for this info. I am going to be decking with DF also under my screened porch so will likely try the preservative mix first before I stain also. Good to hear you have had such good luck with your deck...that is pretty stellar performance.

If you find a source to buy (post #187841, reply #5 of 5)

If you find a source to buy pentachlorophenol without a special EPA license, please let us all know - I'd like to find a place to buy some myself without having to resort to a $1500 minimum pallet buy and EPA reporting. 

My post was somewhat tongue in cheek (the <G>).