Glue or screws? Or?
Use a plastic compatible adhesive. Most of the time, you can get what you need at any home improvement store. PL-300 is one brand. Get a caulking gun to apply it with and you’re good to go.
[tup]
When bonding foam to anything other than foam, I use Liquid Nails for Projects. It’s less than $2 a tube at Wal-Mart. When gluing foam to foam, I use thinned white glue, making sure to add weight in either case to hold it flat.
I 2nd the liquid nails. Works real good.
Screws won’t work, nor will nails. Gotta be an adhesive.
As for WHICH adhesive, go with something cheap & easy to find. I prefer silicone caulk to glue foam to wood and foam to foam, where you don’t have to carve through it. When I will have to carve through a glue bond, I use wood glue. To lay track onto foam (or anyting else) I use latex adhesive caulk. For scenery on foam, I use white glue.
Keep in mind that any glue you add between foam layers will take forever to dry (a week or more, depending on humidity) The ONLY way to avoid long drying times is to use foam-safe rubber cement, which can give you an instantly dry bond. But it’s not cheap.
I used yellow carpenter’s glue. Still holding good, and I’ve banged my head up against the bottom more than once.
I’ve had nothing but bad results with Liquid Nails, it takes FOREVER to dry, even when used for more ‘traditional’ uses like gluing a new toilet paper roll holder to tile in my bathroom. Tube says 48 hours. 2 WEEKS later and it still was not fully cured. My bathroom is huge - it wasn’t getting wet every time someone used the shower or
Two small additions.
Foam to foam, I use low temp hot glue gun. It cools in a few minutes not a few days. It holds almost as well if you use enough.
Caution - some silicon glue will disolve some foam. I use only latex to avoid a bad experience.
I’ve got to disagree here. If you use a large washer–say 1 1/2" to 2", a screw will work.
I 3rd liquid nails.
dekruif
Go to Home Depot, Lowe’s , Wal-Mart, or any hardware store that carries Liquid Nails. It works great. Just place down a sepentine pattern, then slide the foam back and forth a bit before placing into final position. I also place some weight on the foam until it dries just to keep some compression on the joint.
I’m for liquid nails. . .
Here is a picture of liquid nails and foam from my blog.
I used foam board adhesive combined with drywall screws for my first couple of layers. ( I used 1" board) The screws helped keep the foam board in place while the adhesive set up.
The trick was to not let the screws go all the way through so I used a drywall bit on the end of my drill while screwing the board down. All the screws were countersunk & I have had no issues with it in 5+ years.
Gordon