Biscuit jointing Pressure Treated 2x4 's

[Clarence Martinn]

Anyone know if Pressure Treated Lumber can be glued up together , using Biscuits ?

[Marc Rochkind]

Can't think of why not. What issues are you thinking of? Toxic sawdust? Chemical reaction with glue?

[Jamie Buxton]

In my area, pressure treat is sold soaking wet. I'm not sure ordinary yellow glue would be able to lose enough water to harden up.

[Clarence Martinn]

Can't think of why not. What issues are you thinking of? Toxic sawdust? Chemical reaction with glue?

The type of glue needed for gluing up the biscuits to PT lumber. Was thinking of Titebond waterproof glue. While I was cleaning up the backyard, the BOSS let me know he needs a new roof on his Dog House !! :D75MPH winds in a recent wind storm ripped off the Cedar Shingle roof on the right side of the Dog House

[Mel Fulks]

I wouldn't attempt glue just because the PTW might twist so much that it breaks the bond. I would use the polyurethane
cartridge adhesive.

[Sam Murdoch]

GRK screws and - if you really need adhesive - (as Mel writes ^) PL Premium PolyUrethane Construction Adhesive (caulk) - or Locktite or a similar product.

[lowell holmes]

IMO, biscuits are fore alignment. The strength of the joint is derived from the glued surfaces. Dominos might add strength.

[Curt Harms]

Normally biscuits are used with PVA glue so the water swells the biscuits and makes for a very tight fit in the pocket. Unless the PT was air dried all the way through, I would be doubtful about PVA glue. Plus most PT lumber isn't smooth enough for a good joint unless you plane it. I think the suggestion for construction adhesive is a good one.

[Jim Becker]

Yea, biscuits or other splines/tenons/Dominos are great for setting things up, but gluing PT lumber can be a major challenge for the reasons stated. And even with construction adhesive or moisture cured polyurethane glue, it would be best to stack and sticker that PT lumber for a long time to get it "less soaking wet", before trying to assemble it into whatever it's going to be. Consider alternative weather/insect resistance wood, too...such as white (not red) oak, mahogany, etc.

[Mitchell Ristine]

Have you ruled out mechanical fasteners for a reason?

[Edwin Santos]

The biscuit joiner is an excellent tool, but not designed nor intended for an application like this. There's little information provided on what you are building and use/conditions. I am thinking construction adhesive and GRK structural screws may be one avenue.

[Dave Cav]

Simpson Strong Ties.

[Mitchell Ristine]

Just a thought ... (I would NOT use this for furniture or tables or the like, but this is a dog house subject to the elements):

Dado room for rails that sit flush with the surface out of 2"x.75" material. Affix with screws and glue. (sorry, I don't know all the correct joinery terms yet)

383956

[Phillip Gregory]

Gluing pressure treated wood rarely works well as it is typically sopping wet (as in flings drops of water as you cut it) and warps like crazy. I use screws, and if it really needs to stay put, through bolts.

I really do not like pressure treated, it's miserable stuff that is miserable to work with. It's not square, it moves a lot, it smells bad, and it clogs any tool that touches it with pitch and sap.

[Dave Zellers]

I think if I needed to join two 1 1/2" thick PT boards together permanently I would use a full length 1/2" spline and poly glue.

For 3/4" PT, which might be your situation, biscuits and poly glue 'might' work. But I would never do it. I would make a 1/4" PT spline.

But really, for a dog house? Who cares? Certainly not the dog.

[Peter Kuhlman]

So the roof is covered with shingles? I would just use 3/4 PT plywood fastened to 2x4 structure and cover that with roofing of your choice. I did this with our last doghouse and it is still doing fine after 40 years. No need to overthink this.