Gluing 2x6 to OSB?

[John Pariseau]

I'm framing out some window boxes (see: http://www.greenbuildingadvisor.com/articles/dept/musings/installing-windows-foam-sheathed-wall) with 3/4" plywood. The plywood will screw into horizontal girts, and two uprights on either side. The 2x6 uprights will play a little role in some structural stability in this system. I've uploaded a render of the assembly:


340661

The gray beams are 2x6 white pine (actual thickness) and the inner, thin grey box is the 3/4" plywood. The ugly pattern is OSB. I'm going to be screwing through the OSB sheathing into the 2x6.

I was thinking about gluing the 2x6 to the OSB, but am wondering if the change in humidity over time will break the bond of the glue, since OSB probably expands differently than white pine. The area of wood glued will be 6" x 17.5".

Ultimately, the sandwich of Strapping+Foam+OSB will be sufficient to hold the assembly together - I'm just wondering if I can make it stiffer with glue all around.

For glue, I was going to find an "OSB compatible" solvent-based construction adhesive.

Thoughts? Am I overthinking this? The outside of the window box will have am 8" plywood flange, with 7" screws all around.

Thanks!

[Rick Fisher]

Any subfloor adhesive would work for OSB to lumber. I would probably use PL-Premium because of the small area.. OSB to Lumber is a very common thing to glue as OSB floor sheathing is so common in new construction.

[John Pariseau]

Ok - thanks. I'm probably overthinking it anyhow.

[John Pariseau]

So, making progress on the project:

https://c1.staticflickr.com/9/8271/28793418264_03dfc217d9_z.jpg

https://c5.staticflickr.com/9/8050/29331383780_5dba16fd97_z.jpg

All of my windows are in, just need to finish the exterior insulation.

[John Pariseau]

In the second photo, the larger window, the uprights haven't been fully installed, they are all just placed part of the way in. Yesterday I finished screwing it in.

[John Pariseau]

Also, as with this project, I'm questioning my choices. The top and bottom boards ended up being 2.5" tall, but the sides are 6". Part of me thinks I should have ripped the side pieces to 2.5" as well so that it was symmetrical. I didn't do this because I wanted as much wood as possible to screw into - both from the sides through the plywood, as well as from the back and a larger glue surface. Whatever moulding I put on the front will be enough to cover the 3/4" plywood and any accidents that happened when I was cutting the boards, it won't be 2.5".