TL;DR: Expanding foam can be an excellent adhesive for delamination repairs if it is clamped.
As described in some of my other recent posts, I am in the middle of repairing a large delaminated area on my Class C cabover. I had seen a number of people mention using expanding foam as an adhesive for delamination repairs, so I decided to do a test piece using Dow Great Stuff Windows & Doors expanding foam, styrofoam (EPS), luan, and FRP paneling (orange peel surfaced stuff sold at Home Depot and typically used in bathrooms). Here is how I did it:
- Put on disposable nitrile gloves (a must!)
- Squirted the expanding foam on the styrofoam
- Squished the wet foam with the luan a few times to spread it around until it covered the whole surface of the styrofoam and the luan.
- Misted the wet expanding foam on both surfaces with water (expanding foam cures faster with water, like Gorilla Glue)
- Did the same thing on the other side with the FRP.
- Sandwiched the assembly between two 3/4 inch boards and clamped it for 24 hours.
The expanding foam oozed out around the edges and stuck to the clamping boards, so if I was doing this for real I would use masking tape and plastic wrap or parchment paper anywhere the foam could ooze. After it cured the excess foam was easy to pull off but left residue.
When I tried to pull the luan and FRP away from the styrofoam core there was zero give, and the styrofoam core was starting to break before I gave up. Some of the oozing expanding foam had gotten between the luan and the clamping board, and when I opened the clamping boards the expanding foam ripped off some of the outer surface of the luan, so it seems expanding foam is a better adhesive than what they use to make luan.
Based on this test I would not hesitate to use expanding foam as an adhesive to fix delamination in luan/EPS/luan/filon RV walls if I had a way to effectively clamp the area to keep the foam from expanding (if the foam freely expands it is relatively fragile). Although I did not test it with actual filon, the FRP is pretty slick and I figure anything that sticks to it will probably also stick to filon.
As described in some of my other recent posts, I am in the middle of repairing a large delaminated area on my Class C cabover. I had seen a number of people mention using expanding foam as an adhesive for delamination repairs, so I decided to do a test piece using Dow Great Stuff Windows & Doors expanding foam, styrofoam (EPS), luan, and FRP paneling (orange peel surfaced stuff sold at Home Depot and typically used in bathrooms). Here is how I did it:
- Put on disposable nitrile gloves (a must!)
- Squirted the expanding foam on the styrofoam
- Squished the wet foam with the luan a few times to spread it around until it covered the whole surface of the styrofoam and the luan.
- Misted the wet expanding foam on both surfaces with water (expanding foam cures faster with water, like Gorilla Glue)
- Did the same thing on the other side with the FRP.
- Sandwiched the assembly between two 3/4 inch boards and clamped it for 24 hours.
The expanding foam oozed out around the edges and stuck to the clamping boards, so if I was doing this for real I would use masking tape and plastic wrap or parchment paper anywhere the foam could ooze. After it cured the excess foam was easy to pull off but left residue.
When I tried to pull the luan and FRP away from the styrofoam core there was zero give, and the styrofoam core was starting to break before I gave up. Some of the oozing expanding foam had gotten between the luan and the clamping board, and when I opened the clamping boards the expanding foam ripped off some of the outer surface of the luan, so it seems expanding foam is a better adhesive than what they use to make luan.
Based on this test I would not hesitate to use expanding foam as an adhesive to fix delamination in luan/EPS/luan/filon RV walls if I had a way to effectively clamp the area to keep the foam from expanding (if the foam freely expands it is relatively fragile). Although I did not test it with actual filon, the FRP is pretty slick and I figure anything that sticks to it will probably also stick to filon.
