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Discussion Starter · #1 ·
Hello,

I have a rather large 20-year old wood Pergola (20 foot x 20 foot) attached to my house that is in need of serious repair. More than half of the wood is rotten. For some reason the original installers used custom size wood for the framing (posts are 8" x 8" x 12' posts that were milled down to 6" x 6" exactly rather than stock 6x6 which are actually 5.5" x 5.5"). All of the framing is similarly milled from oversized wood. The only standard components are the 2x3 boards used as the top. I decided I want to tear down the whole structure and replace it with a similar structure that is built with standard sized lumber. The two posts are anchored into a cement patio. I will upload a picture shortly. Here are the components I will need:

Posts: The current custom 6"x6" posts are set and mounted into a concrete patio. I plan to buy 2 new posts that are stock 6"x6"x12'. These new posts will be slightly smaller (5.5" x 5.5") than our current 6"x6" posts. We will add a 1/2" thick piece of galvanized metal or piece of wood so the new posts will form a snug fit with the current bracket that is set in concrete.
Framing: I will need three 2"x12" x 20' boards and ten 3"x 8" x 20' boards.
Pergola Top: Currently we have twenty 2" x 3" x 20' boards. I may want to have one small part of the Pergola roof to be solid so we can mount a TV underneath it. Thinking of swapping out the 2" x 3" boards with fewer 2" x 4" mounted face down.

One BIG question is what wood to use. I live in San Diego a few miles from the coast. The Pergola gets a fair amount of sun and a relatively low amount of rain (and no snow). The current pergola was made with green Douglas fir. Over its 20 year life, we repainted the structure probably 5 times and had to several times replace rotted boards. My wife and I want to find a solution that will be relatively low maintenance. The current pergola is painted white. We may paint the new pergola, or we may stain it for a nicer look.

My contracter was recommending green Douglas Fir, No. 1, Green, Resawn 4 sides from rough lumber, but I think this is what was originally used 20 years ago and the pergola has required way too too much maintenance. I was thinking about using Douglas Fir, Construction/Standard, Pressure Treated ACQ 0.4, Surfaced on 4 sides. I thought this more expensive option would be more durable and resistant to rot, but one person at a local lumber yard advised against it. He said that the pressure treated wood is really meant for wood that will be touching dirt, and that it can actually have a smelly offgas. He also implied that this wood better be painted and not stained. He recommended I get Douglas Fir, Select Common, Green, Rough Sawn, Resawn 4 sides. Another possibility is redwood, but I think it will end up costing twice the price of any of the Douglas Firs. I read some good things about Western Red Cedar and Pressure treated Southern Yellow Pine.

I really need some expert advice in selecting a wood. I need to balance price with durability as well as maintenance requirements. I realize the choice may change depending on whether we decide to paint or stain.

If we decide we want the new pergola painted white (or any color), what lumbar type do you recommend and what is the best way to paint it so that the paint will last many years?

If we decide we want to stain it (a redwood color whether or not it is actually redwood), what are the best wood species and why?

Would pressure treated wood be a lower maintenance cost option?


The lumberyard worker suggested that I dry the wood out. It is sunny and 80-90 degrees out every day, he said I should order the lumber and when it is delivered let it sit in the sun for a day or two to dry out before starting construction. Do you agree with this?


Thanks in advance for any quidance!!!

Chip
 

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The odd sizes you are seeing is because it is timber framed it is just timbers that were not planed down like normal lumber.

Do you have a plan or does it look easy to get the old posts out of the concrete.
 

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Discussion Starter · #3 ·
Hi Neal,
Thank you for helping me. I need to take some pics of it later today in the day light. I did not think there would be a problem removing the old posts. If I upload some photos of the posts, would you be able to give advice on what to expect?


Also, any recommendations about the wood? Pressure treated vs green? Which treatment requires the least amount of maintenance - paint or stain? I know there are different types of paints and stains, so any recommendations would be appreciated.
 

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If the posts you are removing are set in the ground they may be set in concrete (I believe you said "into" the patio) if so once removed you will have a large enough hole to accommodate any reasonable substitute.
You might think about forming and pouring concrete piers with posts anchors. This would raise the post butts above ground level where the mold and fungus rot occurs. It would be easy enough to clad the posts down to deck level with something (cedar?) sacrificial and easy to replace.
 

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How about mix the lumber? Pressure treated 6x6 for posts and select fir for other parts? In nj and pressure treated lumber is what I'd use but that's because I'm budget minded and my main source is homedepot. Some people in the forum have recommended untreated douglas fir and I assume that is because it works long term where they are. PT lumber WILL twist while drying. Your 2x3 for certain. Good standard lumbers may not be readily available also, but design can compensate - using built up beams instead of single solid beams, etc.



When setting the posts on the post base, add some washers (or other kinds of spacers) so the post end grain is not in direct contact with the base. I don't know how much precautions are taken where you are against water.


If you like the contractor, and you don't know much about the materials and such, best if you follow the contractor's advice.


Any wood lumber will turn gray if not protected. Stain is the best choice. Using paint could be one of the reasons for wood rot. Paint forms a thick film and water gets trapped under the film, accelerating the rot. I used solid stain, 2 coats, on deck rails. I had to restain the floor after 3 years but the rails were fine. Cabot is the brand I know and trust. Another reason for using stain is that it's lot easier to scrape if it peels.
 

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Discussion Starter · #8 ·
ChuckTin thanks for the advice, does my second picture clarify the situation? I am hoping we simply pull/cut out the old posts exposing metal brackets that are set in the concrete patio. Then the new posts can be slid in, with just 1/" of clading on two sides to get to the required 6x6 dimensions. Sound reasonable or do you see potential problems?


Carpdad, thanks for all of the insights. I am fine with mixing materials, but if we go with the stain option wont the pressure treated posts look very different from the rest of the pergola? The lumbaryard said i should buy the green wood and let it sit in hot sun for several days. Do you recommend this?
 

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I zoomed in on the post base and maybe you have anchors attached to slab and etc. Unless you know already you won't be sure till you pull that cladding off.
 

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Don't know your locale but here in FL. Pressure Treated wood is not insurance for early fail. (Isolating it from ground contact does help.)
None the less I would use it unless you are pressured into something else.
If you're really ambitious you could go for metal posts with full length cladding.
Anyway _if_ your mounts are post sockets or similar you won't know their condition till you view them up close and personal. Then you can R&R as needed. Firstly paint the post butts, top and bottom - use CAREFULLY CopperTox or similar, get it from a farm store smallest container you can find. If nothing else coat the endgrain with thin(!) topping of Bondo. And once the posts are replaced I'd paint the metal with high-zinc primer. If you splash over with the painting it'll be covered with the cladding anyway.
 
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