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How to Finish Rough Cedar Pergola

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Forum topic by stillwaters posted 12-01-2020 02:06 AM 425 views 1 time favorited 13 replies Add to Favorites Watch
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stillwaters

1 post in 57 days


12-01-2020 02:06 AM

I have an outdoor pergola structure, rough cedar, built mid-2019, so should be dry enough for finishing.

Currently no finish on it, would like to apply urethane or stain to protect wood (carpenter bees, weather).

Like the look of the raw cedar, prefer not to cover it or change color too much.

Which products would be well-suited to this project, and would it need to be applied with thinner in view of age of structure (1 1/2 years)?


13 replies so far

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SMP

3203 posts in 881 days


#1 posted 12-01-2020 03:29 AM

Are you saying you like the grey that cedar turns outside when left unfinished? Or you like the color it is when cut? I avoid poly outdoors as maintenance is a nightmare IMO. For exterior I like using a good exterior grade transparent or semitransparent stain with UV blockers. I usually get the Behr Premium Plus from Home Depot. The semitransparent tends to help homogenize the various colors cedar can be. The transparent will be more “natural”. FYI, their premixed “Cedar Naturaltone” is on the orange side IMO, and the “redwood naturaltone” is on the red side. They also have natural or you can get them to mix other colors. I just apply with a 3/4” nap roller, but you can thin it and spray also.

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Rich

6398 posts in 1565 days


#2 posted 12-01-2020 03:37 AM

General Finishes Outdoor Oil is a good option. You can check it out on their web page and decide if it’s a product you think would work for you.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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SMP

3203 posts in 881 days


#3 posted 12-01-2020 04:09 AM

I’ve personally never used the General finishes oil, but have used Penofin oil on exterior ipe decks and it works well. I love all the General Finishes products I have tried, so I am sure that would be good also.

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Kelly

3297 posts in 3920 days


#4 posted 12-01-2020 05:10 AM

ANY finish you put on it is going to be a nightmare, and will turn the gray a beautiful gold-ish.

It’s cedar, so it’s just wood. It will dry and shrink and in time give you that gray, ALONG with the shrinking that brings cracks and spits that make that gray a whole lot less desirable.

To stop the cracks and splits, YOU HAVE TO replace lost moisture. Any non-hardening oil will solve that problem. Even used motor oil. Even the ugly black stuff that came out of a big tractor trailer rig. Interesting, in spite of the seemingly pitch black of the used oil, you’ll still get a beautiful gold cedar finish.

Of course, you can use brand new oil too. It could be the cheapest Walmart stuff you can find, Chevron Shingle Oil, mineral oil, even agricultural oil for orchards (mineral oil with emulsification) or other, as long as it’s non-hardening.

To apply it, everything is fair game, be it brush, roller or sprayer. Regardless which you use, thin it about 15% to get max penetration. When done, if it soaked it, let it have more. Ideally, you’d penetrate the wood fully with it, but that would be a lot of gallons at once. Go for as much as you can, especially on the roof.

Interestingly, a very generous application subjected to hot summer sun will look like you did nothing in a few short months, a second coat will seem to not have fared much better, but a third coat would be evident years later. This is because the applications do not evaporate (thought the thinner does). Instead, they wick deeper into the wood and are cumulative. For this reason, the more aggressive you are early on the better the wood will hold up over the years, and the easier it will be to add maintenance coats later.

If aggressive early on, you can coast later, but will still need to get around to it to keep it all well and good.

I have done, for one example, fences that look FAR newer than all those around them ten years in, though they were all built at the same time. So too with a garage door I built using leavings in a cedar spalt pile from a buddy’s mill.

This all applies to cedar roofs too, of course. In fact, the oil, if it penetrates enough, keeps the shakes or shingles flexible enough that they can be walked on without breaking them in the middle of a hot summer. Too, a pieces of cedar saturated with oil will not take on water that, if it freezes, will contributed to the splitting and cracking.

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Aj2

3599 posts in 2774 days


#5 posted 12-01-2020 05:38 AM

I don’t have any recommendation for protecting cedar from Mother Nature. But the carpenter bees i recommend a shot gun.
I get them here in the spring and we do battle. One year I brought my shop vac in the house to clean up some and when I turned it on a big black and yellow carpenter bee flew out. It took me a few minutes of ducking and striking but I finally won. My living room look like a barroom brawl went down.
Good Luck

-- Aj

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bilyo

1256 posts in 2078 days


#6 posted 12-01-2020 03:13 PM



I don’t have any recommendation for protecting cedar from Mother Nature. But the carpenter bees i recommend a shot gun.
I get them here in the spring and we do battle. One year I brought my shop vac in the house to clean up some and when I turned it on a big black and yellow carpenter bee flew out. It took me a few minutes of ducking and striking but I finally won. My living room look like a barroom brawl went down.
Good Luck

- Aj2


Do a Google search on carpenter bee traps. They work and are easy to make. They work based on the fact that the bees go for existing holes before they drill new ones.

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Lazyman

6393 posts in 2363 days


#7 posted 12-01-2020 04:31 PM

I doubt that most finishes will deter carpenter bees. I’ve had them bore right into a board that was stained about a year before. You can buy a pesticide that targets them but I think that it has to be applied monthly while they are active. I don’t like to spray pesticides myself so I would try the traps before going that route. I think that you can buy a lure for “baiting” the traps to make them more effective.

Also, film finishes, such as a spar urethane, can be a maintenance nightmare. They tend to crack fairly quickly and then they trap moisture underneath leading to mildew and other nasty problems. Re-coating will probably require completely stripping off the old finish. A penetrating oil or stain with UV inhibitors will do a better job protecting the appearance and you can usually just apply a new coat when needed.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Bill_Steele

748 posts in 2707 days


#8 posted 12-01-2020 04:34 PM



I don’t have any recommendation for protecting cedar from Mother Nature. But the carpenter bees i recommend a shot gun.
I get them here in the spring and we do battle. One year I brought my shop vac in the house to clean up some and when I turned it on a big black and yellow carpenter bee flew out. It took me a few minutes of ducking and striking but I finally won. My living room look like a barroom brawl went down.
Good Luck

- Aj2

Here ya go > https://www.lumberjocks.com/projects/237738

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Aj2

3599 posts in 2774 days


#9 posted 12-02-2020 01:02 AM

I’m not building a house for bees. You gotta be out of your mind.
Thanks for the link
Good Luck

-- Aj

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Foghorn

929 posts in 362 days


#10 posted 12-02-2020 01:24 AM

Messmer oil every two years if you don’t like grey/silver.

-- Darrel

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Chenier

32 posts in 683 days


#11 posted 12-02-2020 02:23 AM

Thompson’s Water Seal

Thompson’s is clear and doesn’t tint the wood. It does darken it slightly – like the wood is wet. You can brush it on or apply with a common garden sprayer.

We have a dock whose deck is made of white cedar. It’s out in the elements 24×7. Thompson’s every 2-3 years works well. Refresh when water stops beading on it. The deck is now 13 years and going strong.

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PCDub

232 posts in 1220 days


#12 posted 12-02-2020 02:17 PM



I’m not building a house for bees. You gotta be out of your mind.
Thanks for the link
Good Luck

- Aj2


They are important pollinators; alternate living spaces would be better than killing them!

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Lazyman

6393 posts in 2363 days


#13 posted 12-02-2020 02:33 PM



I’m not building a house for bees. You gotta be out of your mind.
Thanks for the link
Good Luck

- Aj2

LOL. It’s not a condo. Think of it as a brothel with a vice squad waiting in side.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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