Gluing Treated Wood - Question of the Week

January 7, 2008 by thewoodwhisperer
Filed under: Question of the Week 

This week’s question comes from Brian. He writes:

“Quick question on joining treated pine - I would like to face glue surfaced 2×6 treated pine boards. Does the fact that i am using treated lumber reduce the strength of the joint or make the glue less effective somehow? This is for an application that will have to be waterproof.”

My reply is actually an excerpt from an article I found a while back from Iowa State Univeristy. Full Article Here.
Treated Wood“Deposits on the surface of treated wood present problems in gluing. Oil-type preservatives typically present more problems than waterborne treatments. Wood treated with very high retentions of creosote or pentachlorophenol in heavy solvents is essentially non-gluable. Low retentions of penta in light solvents may be somewhat more readily glued than wood treated with creosote. Wood treated with waterborne chemicals usually can be glued without major problems, if properly dried. Planing or sanding the surface before gluing is recommended to enhance bonding. Select the adhesive appropriate for the exposure condition among conventional wood adhesives. Only resorcinol resin glues provide completely waterproof gluelines with wood; urea resin glues and polyvinyl resin adhesives generate only modest water-resistant glue bonds. Some types of elastomeric construction adhesives offer good resistance to moisture and are much more tolerant of high wood moisture contents and low temperatures than conventional wood adhesives.”

If anyone has anything to add, please do so in the comments section. I personally have very little experience gluing treated wood.

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Comments

11 Comments on Gluing Treated Wood - Question of the Week

  1. Vic on Mon, 7th Jan 2008 10:57 pm

    2. It probably goes without saying, but wear a dust mask if you sand or are exposed to the dust of treated wood in any manner. I’m not sure of the newer treated woods, but all of the older methods used some pretty nasty stuff and better safe…

  2. Mark on Tue, 8th Jan 2008 7:54 am

    3. No, you can’t glue it. However when you nail or screw into it be certain to use stainless steel. Regular steel will fail in a much shorter time, due to the chemical reaction with the preservative.

  3. tom hunt on Tue, 8th Jan 2008 9:03 am

    4. I’ve had pretty good results using polyurethane glue on outdoor projects built from treated pine.

  4. Steve Quillian on Tue, 8th Jan 2008 9:51 am

    5. Not being sure of what it is you are building, the strength necessary and all that, only that it has to be waterproof, there are other woods that can be glued. Cypress is a highly weatherable wood and while it’s not as strong as a treated pine, it will last just as long in many conditions and glues exceptionally well. I use it to make windows here in Tampa, Florida where moisture is a problem. Its an oily wood that grows in the swamps and doesn’t rot for years after it dies. Could you use an alternate wood?

  5. Keith on Tue, 8th Jan 2008 10:27 am

    6. I’m based in the UK where we have pretty well banned the use of creosote so our treated timber is now tanalised which can be glued. The only 100% waterproof adhesive easily available in the UK is Polyproof, this is a resorcinol/ phenol/ formaldehyde; I’m not sure if this is available in the US but you should find something similar. The only downside of this is the dark red glue line.

    Avoid polyurethanes, long term they do not like to be cycled between wet and dry and in my experience the bond fails after a few years.

    Epoxy is another option, not as waterproof as resorcinol but sets clear. The wood needs to be completely dry though if you want a decent bond.

    Hope this helps

    Keith

  6. robert on Tue, 8th Jan 2008 2:56 pm

    7. I have face-glued treated 2 x 4’s to make 4 x 4’s and had no problems. I don’t know the type of treatment. The boards were standard treated lumber bought at Lowes and were slightly green in color.

  7. Tom on Tue, 8th Jan 2008 9:19 pm

    8. Source for the tech note on gluing treated lumber is Iowa State U. Extension Service.

    http://www.extension.iastate.e.....PM1033.pdf

  8. matt on Wed, 9th Jan 2008 6:58 am

    9. I have never had to face glue PT lumber but when I finish a basement I rely on construction adhesive to do a majority of the holding on the pressure treated bottom plate. It may not be pretty but I am pretty sure it would hold up just fine.

  9. Robert on Wed, 9th Jan 2008 10:36 pm

    10. Personal experience with Gorilla Glue: it failed to perform; picnic table built with treated pine.

  10. alexander on Sat, 12th Jan 2008 8:22 am

    11. REcorcinol made by dap is very expensive but very effective! I does leave a red line adter cured. THe glue joints are very brittle; meaning they do not take shock very well. But the joint is bullet proof under the atlantic ocean. LOL. Since the red line it leaves is very hard to mask, use masking tape to protect the part of the project you want to keep clean. Another issue is: thoroughly scraping, sanding, and planing the glueline after fully cured. REcorcinol takes about 2 days to fully cure, after that your gold.

    hope this helps

  11. alexander on Sun, 13th Jan 2008 11:24 pm

    12. I know that PL premium or PL 400 holds extremely well of pressure treated lumber. Fills gaps, drys rock hard, and is 100% waterproof!

    peace

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