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Weather proof untreated lumber

Hello, I am building a very large Pergola (800sqft) over my patio of mostly red oak & white oak that I timbered off my property. I am concerned about preventing wood rot, which I understand is highly likely where ever the wood overlaps and creates an area where wetness can build up and not dry out creating an area that can start to rot. Before I complete the building of this I would like to make sure that I do do whatever I can to help prevent any wood rot, I know I probably can not stop it completely, but I would like to do what I can to slow it down. Can you please give me some ideas, products to use, or and advise to slow/prevent wood rot.

I have heard that I probably should not have used red oak, but this is the tree of abundence on my property.
I have read that I could use something like: Bora-Care is a concentrated termiticide, insecticide and fungicide treatment. That should prevent the Fungi from forming and rotting the wood. I also read that I should also use a water sealant over the Bora-Care type product.

I also read that you can use something to keep the wood separted, one suggestion was torch roofing membrane to put on the top edge so when I put my top 2x6's on the top there should be no wood on wood where it will retain wetness. Along this line, I thought about the product that is used for bed liners. There is some of that rubberized product that you can get in 1 gallon cans, I thought that maybe I could apply that on on the top edges. On the main beams and then on top of the 2x6's that will top, so when the whisteria grows and covers the wood that maybe the wodd would be protected somewhat.

Other than starting over due to the fact that I used red oak what are my options to prevent/slow down any wood rot that is going to happen. Any assistance or suggestion would be greatly appreciated.

Thanks, Dave

Re: Weather proof untreated lumber

Traditional pergolas would not have any kind of roof on them, but be an open trellis to allow vines etc. to grow on them. Several years ago I built a 10 X 10 pergola out of douglas fir here at my home in Portland, Oregon. I elected to put a corrugated plastic roof over the entire structure, as I like to sit out there and hear the rain falling on the roof as I drink my coffee. The point is though, that all the joinery is protected from the constant rain and drizzle during Portland's long, wet, mild winters. After several winters, with nothing more than paint on the wood, there is no sign of rotten wood anywhere. The paint itself also holds up better since rain never touches most of the structure.
The milk glass plastic roofing also protects against the hot summer sun while leaving it bright and cheery underneath.

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