Gluing Treated Wood

Article - January 7, 2008

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.
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.

Discussion

Vic January 7, 2008 10:57 pm

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…

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- Bill Blefere June 7, 2017 12:23 pm
  
  I use to have one head but after sanding without a mask I have 2. The moral quit while your a HEAD
  
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Mark January 8, 2008 7:54 am

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.

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- Pasqualey March 7, 2015 7:39 am
  
  I believe stainless steel would be over kill here. PT lumber will eat away aluminum but exterior grade screws and nails would be fine. I hope so or my deck is going fall down!!:)
  
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tom hunt January 8, 2008 9:03 am

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

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Steve Quillian January 8, 2008 9:51 am

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?

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Keith January 8, 2008 10:27 am

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

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robert January 8, 2008 2:56 pm

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.

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Tom January 8, 2008 9:19 pm

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

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

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matt January 9, 2008 6:58 am

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.

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Robert January 9, 2008 10:36 pm

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

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- Scott July 7, 2015 9:34 am
  
  Don’t built furniture your gonna sit/eat on with treated wood
  
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  - Sal November 26, 2017 4:47 pm
    
    I love the grain on 3/4×6 weathershiled boards:
    I made a desk 5.5ft x 30″ glued them together with Gorilla Glue stained and used polyurethane finish. I love the finish but problems arose as warping resulted and gaps opened up. It seems that this wood is too soft and not resistance to indoor temperatures.
    
    Reply
alexander January 12, 2008 8:22 am

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

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alexander January 13, 2008 11:24 pm

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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Greg Niederhaus September 8, 2009 7:46 pm

I would like to use the planks from a deck I built to lay an interior floor. My thought is to run the under sides through a planer, make lap joints to hide the gaps, and glue the planks to each other as I screw them in. Being that we typically leave a gap between planks for exterior use, can I get away with this idea if I leave an inch gap around the perimeter? It is for a restaurant and they don’t want food to build up in gaps. Dimensions are 12 by 12 feet. Any advice would be appreciated!

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- thewoodwhisperer September 8, 2009 8:32 pm
  
  Hey Greg. As long as you allow some room for expansion and contraction of each board, you should be fine. I don’t think you need a full inch around the perimeter. 3/4″ should be more than enough for that size room. And just keep in mind the time of year and the relative humidity. If its humid right now, you can install the floor nice and tight because the dry winter heat is on its way.
  
  Also make sure you let these boards acclimate. I would bring them inside for as long as you can before the installation. The outside humidity level will most likely be very different than the inside. So its important to get the wood acclimated properly before the install.
  
  Hope that helps.
  
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- Ken Farris March 8, 2019 5:40 pm
  
  If you did not leave the wood in the dryer area that you installed it in for at least a couple of months to give the wood time to dry out it will 98 percent of the time shrink and bend after application due to the monster leaving the wood. I do not know of any thing that would hold it togather at that point due to the wood has to eather shrink and pull the joints apart or if the joints somehow hold then the wood would split in half to give it the movement required. You need to buy pre dryed lumber or give it time to do it natrully to prevent this.
  
  you need to put any lumber that has not been dryed as tight as possible because it will swrink always.
  
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george nimo June 17, 2011 6:18 pm

will like to know the best glue to use to glue down treated wood to basement concrate floor .i am going to put a plywood on it as a sub floor for laying a hard wood floor .thanks.

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- thewoodwhisperer June 17, 2011 6:33 pm
  
  I think you just might go with construction adhesive George. But you may want to double check with some flooring experts.
  
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Sammy Little July 16, 2013 3:00 pm

I just bought some “F-26” adhesive at Lowes and it says on the front: SUPER For Deck and Treated Lumber. It is cheaper than many of the gun adhesives, $4, and it is made by Leech.

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Tony Allen July 18, 2014 8:00 am

I am custom building 26 porch columns. 8 foot tall in the past I made some with 10 2 x 4 s not treated for the tapered staves… now the customer wants treated wood …..it has to be strong and not come apart under pressure …what will be the very best Glue for this application

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- Marc Spagnuolo July 20, 2014 11:56 am
  
  I don’t know about the very best, but there are some decent glues recommended in this article that you might want to consider.
  
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Charles C. Lloyd April 3, 2015 2:56 pm

Titebond III anyone?

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- Thomas Payne September 22, 2017 2:12 pm
  
  I’ve had great luck using Titebond III on treated lumber. The trick is to use kiln dried PTL and make sure to plane both sides. I made 4 post caps and 2 gates(2×6 laminated to 1×6) with no issues so far and they get full sun all day.
  
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Jim Pelletier February 17, 2016 2:24 pm

Could you please speak English? Just tell us what glue works and what glue doesn’t.

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- Marc Spagnuolo February 18, 2016 11:46 am
  
  Hey Jim. Sorry you’re having trouble understanding the article. As I stated pretty clearly, I don’t have personal experience with treated lumber. So I posted an excerpt from an article which states that treated wood is difficult to glue. I then threw it out to the audience to see what glues they recommend. There are quite a few recommendations. Fortunately, it’s all in English so all you have to do is take the time to read it. :)
  
  Reply
  - Ambiguous Sloth March 8, 2019 3:55 pm
    
    haha
    
    Reply
Dave Milden February 28, 2016 12:30 pm

Hi I am hoping to make 2 x curved timber beams for the top of a pergola with 8 x 2 running the opposite way out of 4 x 1 treated timber. As anyone got any advise on this especially the right type of glue to use.
Thanks

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Ray January 7, 2018 8:46 am

Hi ! After sanding pressure treated wood my deck fell off too !!

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- ericson osorio June 8, 2019 6:17 pm
  
  are you serious ?!
  
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Ryan April 3, 2020 8:20 pm

Dude, if your deck fell off, I’m sure it wasn’t because the glue you used failed lol. To be honest, most outdoor construction projects don’t require a ton of joint strength besides decks and playgrounds (garages and sheds are usually kept covered by exterior materials like siding and roofing. I wouldn’t worry about gluing a pergola unless you’re going to put a spare bedroom on top of it. Learn how the professionals do it and why they do it that way. I’ve never used glue on a deck. I’ve never met anybody that did unless they are gluing planks to add protection against bowing and crowning. If you use proper fasteners, it should last for years with the right design. Essentially, there’s no use in adding the extra strength of glue to a joint that would never be strong without glue in the first place. Screws and bolts, when used correctly, can hold up to a lot of abuse. I’m not saying don’t use glue, but ask yourself if what you’re gluing will still be strong in 5 years of normal use without glue. If yes, then you can decide what glue to use. If not, maybe just go back to the drawing board and design something more effective. Don’t get upset with the people on here sharing what’s worked and not worked for them. Nobody is going to jump in your face and say, this is the product for you! But if you’re polite and explain what you’re building with as much detail as you can, I reckon one of these people would have a few helpful suggestions.

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All Angles Carpentry May 20, 2020 11:15 am

Standard pressure treated would need to dry out good prior to face gluing. If it isn’t kiln dried before and after treatment then you can expect warping and shrinking, making face gluing as a sole means of adhering the two boards not optimal. Perhaps the usage of screws, nails, or dowels with wood glue or thicker adhesive recommended for pressure treated lumber would result in a better bond. As stated use hot dipped galvanized fasteners or stainless. The coated fasteners for pt are okay, but it’s just paint; some comes off upon usage allowing for areas of the fastener to corrode over time, and eventual failure. It’s always best to try to build in a way that doesn’t leave loads depending on fasteners alone. Notches in posts acting as pockets for horizontal framework are great for this in general.

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Gluing Treated Wood

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