Gluing Treated Lumber

Preservative treatments leave wood wet. But once it dries thoroughly, adhesives should be able to grip. October 2, 2007

Question
Is there an adhesive, other than two part epoxy, that will bond pressure treated material face to face? If I finger joint, spline or biscuit joint 3/4 pressure treated plywood edge to edge, what glue can I use? I have used construction adhesive in certain applications that was successful, but I need a more fluid application for face to face and edge to edge finger jointing.

Forum Responses
(Adhesive Forum)
From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
The problem with PT wood, if they used a water-born treatment (green colored), is that the wood is still quite wet and so many adhesives will not work well. Once dry, just about any adhesive will work well. If they used creosote or oil-born adhesive, it is probably impossible to get a real good bond with the oil on the surface.

When machining PT wood, the risk from contamination of yourself, the workplace, etc. is extremely high. At the least, wear a respirator and throw your clothes away and take a very thorough shower.



From contributor B:
I've had success with Gorilla Glue when using lumber treated with the water based preservatives.


From contributor N:
I would be led to believe that if you're trying to edge glue treated ply, then it's in a weather environment. This I donít think I have ever considered but it might be the only product you can use. What is its application? If you're married to having to do this, I would consider having a facility treat some bc or better ply. This is probably out of the budget. At the least I would sticker it very flat and use whatever method to dry it out. Time, who knows, but get it as dry as you can. Dr. Gene probably knows the ins and outs to that. As for gluing it up, I would create a lap joint at least 2 inches and hopefully the plies afford a 3/8 even removal with not cutting halfway through a ply. Biscuits will never work. Spline the stuff. It will swell and won't work much better. You will end up fairing the seam. I would not interject a foreign species wood. Treated is psycho in how it ends up moving. With the lap, itís ply to ply. What is this for? Oh yeah, the glue. We use two part epoxy on treated; it's not so bad to work with. Not a good resorcinol application and for the most part the stuff seems to be losing its desire. If poly, make sure it is clamped for a good while, four days at least. It's still expanding at 2 days.



Form contributor B:
Have you tried Tidebond III? It should work when and if the treated lumber is very dry (at least 11-12%).


From contributor S:
I am building a house with pressure treated basement. We have to glue all the sheathing to the framing. The lumber yard sells tubes of caulking/glue made for P/T lumber. Not sure if it will bond surface to surface or if it is more of just a sealer. Might want to research that a bit.


From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
I believe that the adhesive contributor S is using is a mastic adhesive.