If you’re a fan of fresh air, blue skies, and a lush garden, you may think that a home’s exterior is more attractive than its interior. It is not just the style and material you have to be selective about, though. Working on an outdoor project means having to work with pressure-treated wood.
What materials can you safely use on pressure-treated wood? Is gluing the wood safe after you have treated it? Which glue works best for pressure-treated wood?
We know the barrage of questions that flow into the mind of every person who undertakes an outdoor project. In this article, we will discuss at length all about gluing pressure-treated lumber.
Problems With Gluing Pressure Treated Wood
When you have treated your wood to make it suitable for the outdoors, you may have to face certain challenges if you try to glue the same wood later on. The surface of treated wood will generally contain substances from the chemicals and preservatives that might give you a problem when trying to glue the wood.
If you employ oil-type preservatives during the treatment process, you will face more problems when trying to glue the 
same wood later. Waterborne treatments are slightly less challenging in this regard. When you treat wood with high retentions of pentachlorophenol or creosote, the heavy solvents render the wood incapable of receiving glue.
You can expect your wood with low pent retentions to be more acceptable towards glue, but wood with creosote treatment will be impossible in this instance. You must consider using waterborne treatments for your wood if you plan to glue it later because this particular treatment does not diminish the lumber’s gluing potential.
Waterborne chemicals become responsive to glue once they have dried out completely. You can also sand or plane the surface first so that you encounter no problem at all in gluing the wood later. This step will only enhance the bonding potential of the lumber.
What Glue Works Best For Pressure Treated Wood
You will come across a wide variety of conventional lumber adhesives in the market. Still, you must try to get the one that is the most appropriate considering the exposure condition. The only waterproof glue line for your wood is resorcinol resin glues.
Polyvinyl and urea resin glues are the adhesives that will only give you a modest water-resistant bond. There are also certain types of elastomeric construction glues that give you competent moisture-resistance and prove highly tolerant of high moisture contents in the woods. The temperatures in these adhesives are also lower than the conventional ones.
To help you narrow down your choices, though, here are the four basic types of glue you need to always keep on hand for wood construction projects.
- POLYURETHANE GLUE
Polyurethane glue is a marvelous water-resistant adhesive. It works so well against water that material does even better when it is somewhat damp with moisture. This glue’s characteristics make it a fine choice when you have to work on projects featuring pressure-treated wood.
Pressure-treated wood is often damp, and using polyurethane glue on stock dried in a kiln means that you will have to sprinkle some water on it to make it work. It is mostly a problem when you want to join end grain to end grain in terms of strength.
Polyurethane is a winner in this regard because it handles porous end grain wonderfully. One of the most popular brands of this type of glue is Gorilla Glue (Amazon Link), which is what I use.
- TITEBOND III
This adhesive is water-resistant and has good sandability. It gives you approximately ten minutes of open time. This specific adhesive quality is that it is water-resistant only when it is dry, but you can easily clean its water when it is wet.
Titebond III (Amazon Link) makes an excellent choice when working on outdoor furniture, cut boards, or other items where moisture is present.
- YELLOW GLUE
People of every generation are perhaps familiar with the yellow glue, the carpenter’s arsenal. Yellow glue comes from the family of polyvinyl acetate and is an aliphatic resin. If you plan to build cabinets or furniture pieces, you can trust yellow glue to take care of most of your gluing needs.
The benefits of this glue are that you can clean it with water while it is still wet and it turns stronger than the wood you are gluing together once it cures. Yellow glue also sands better. However, it is not a good choice for damp materials.
- CYANOACRYLATE
This is another worthy candidate in the adhesives department. Cyanoacrylate bonds faster, and you can find it in various viscosities, from watery to jelly thick. You can use the thin variety for pouring into punky wood as reinforcement.
The thicker cyanoacrylate is good for filling gaps. CA, however, is brittle glue. This will not work for places where daily use can crack it down.
Can You Use Liquid Nails On Pressure Treated Wood?
Liquid nails tend to give you mixed results. In most cases, liquid nails dry out over time and very likely lose their adhesive power. You need to use redwood or treated lumber when coming in direct contact with cement.
In most cases, results have proved that treated wood does not take to adhesives including liquid nails.
Does Gorilla Glue Work On Pressure Treated Wood?
Gorilla glue has many exceptional qualities in wood projects, one of which is exceptionally strong. The gorilla glue label reads that it is the toughest glue on the planet, and most constructors agree wholeheartedly with this.
It is difficult to quantify the strength of gorilla glue in woodworking stations. However, if you apply it to a good fitting joint, you will observe gorilla glue as the strongest of the many wood species, you will adhere to it.
Gorilla glue undoubtedly creates an excellent. You can let go of your fear of a proper joint failure in adhesive where you use gorilla glue.
How To Join Two Pieces of Pressure Treated Wood
If you have wood pieces dried in a factory, you can consider joining the wood straight and gluing it together. However, you must be prepared for considerable pulls on the joints that will eventually occur from wood movement over time.
You can try drilling through the centre of the boards and running a couple of threaded rods through the wood when you join it together. You must countersink the ends where you could glue a plugin to cover the rod from plain sight.
Is It Possible To Glue Pressure Treated Wood Pieces Together?
You must be aware that the treated lumber you will obtain will surely have chemicals and preservatives injected for protection against the elements. Protection and treatment are necessary because the wood has to stand against the 
elements that could warp it and prevent insects and molds from destroying it.
Treated lumber is not uncommon in new homes, outdoor spaces, decks, fences, boat docks, etc. Pressure-treated wood has the potential to last for more than forty years, mainly because the pretreatment extends and maximizes its life. At the same time, the treatment of lumber can make it difficult for glues to adhere to it because chemicals from the moisture make the wood damp.
However, pretreatment may make gluing difficult but not impossible. You can follow the steps below to prepare for gluing:
- You must choose an epoxy. They’re available in wet and dry, but the purpose of both is the same.
- You must dry the wood thoroughly, for which you have to place it in a dry location. You can also make use of a dehumidifier in the room where you will keep the damp wood. If you plan to dry the treated lumber outside, you must only place in direct sunlight at the hottest time of the day and at no other time.
- You can use a dryer to blow hot air over your treated lumber from end to end. Store the wood in a dry place and allow it to rest for at least three whole days.
- Prepare the wood for gluing by sanding the surface of your treated wood, the area, especially where you plan to use the glue. You could begin by using medium-grit sandpaper and then turn to fine-grit sandpaper. Remove the dust from the surface of the wood after sanding using a tack cloth or a rag. Make sure the area is as smooth as can be.
- You can proceed with the gluing process now. It is important to use the proper tools, equipment, and safety gear during this process.
Final Thoughts
Treated lumber enhances the life and strength of your outdoor wooden pieces. Treated wood can last for more than forty years if you follow the right practices during your construction project, including gluing the wood in the right way.
