Garden arbor - material and finish

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Forum topic by Ben posted 04-12-2016 01:12 PM 424 views 0 times favorited 2 replies Add to Favorites Watch
View Ben's profile


244 posts in 2280 days

04-12-2016 01:12 PM

I’ll be building a small garden arbor for a customer.
Given the curved rafter design, it requires a 2X12. So I’d like to use conventional Doug Fir (select). I’ll hand pick every piece. No one stocks Cedar 2X12 and it’s literally 10 times the cost. I could get rough sawn Sapele/Mahog but that would be even more after my labor to surface it.

I made a prototype rafter.

I’m just wondering – is this going to hold up OK, or am I effectively exposing all the end grain by cutting the curve? Or is it a moot point because water will just roll off?
Assuming I am OK to proceed, what is the best oil finish I could put on this to preserve it all as long as possible?

I plan on capping the posts, and setting the bottoms on bases attached to piers. Half the structure will be attached to the house. Haven’t designed the whole frame yet, but fastening will of course be done in the least intrusive way in terms of moisture entering the wood.


2 replies so far

View JBrow's profile


750 posts in 342 days

#1 posted 04-12-2016 09:07 PM


I built a red oak picket fence which has held up well. My design covered all end grain and angled surfaces to shed water. I also feared water could be wicked into the end grain of the posts so I held the fence posts off the ground so the end grain at the bottom was suspended in the air and the tops were capped. The posts were hollow boxes that fit over and were mounted to PVC pipe. I apply a Sikkens brand product annually to the red oak. However, it seems to last longer than a year on various pines; about 4 years on my pressure treated privacy fence.

Although I introduced no cut curves in the design of the fence, I would have covered the curve-exposed end grain out of an abundance of caution. While the arch will shed water at the center, as the water runs down the arch, it has a greater opportunity to enter the arch toward the ends. A ½ thick (maybe even ¾” thick) with bevels cut along the face to shed water would probably have been my approach to cover the arch you are planning. If the width of the arch’s cap extends beyond the faces and ends of the arch by at least ¾”, these drip edges would help keep water away from the arch. When attaching the arbor to the ground, ensuring an air gap between the posts and the piers and that the piers shed water would help protect this vulnerable part of the arbor. Also, I would think that using a standoff of some type to make the house connection could increase longevity of the arbor and protect the house. My first thought is to use copper tubing or pipe as bushings. Copper will last a long time and weather nicely. Although more expensive and softer metal, stainless steel fasteners will not rust and should last a long time. I found that Twin Creek Log Homes, a Sikkens dealer, is knowledgeable of outdoor finishes. They may be able to direct you to the most appropriate finish. If interested, their web site is:

View CaptainSkully's profile


1407 posts in 2981 days

#2 posted 04-16-2016 02:42 PM


The fact that you knew to ask is the most important thing. Yes, do use some sort of sealer anywhere you’ve exposed end grain. The same as you’d paint on the post bases where they meet the footing.

-- You can't control the wind, but you can trim your sails

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