Be careful that stuff goes soft and gooe in the heat i had a door card and in summer it all came unstuck i found the best glue called ninja glue from screw fix sticks like shiiiiiit purpe tin
I used to use this type of adhesive on foam at work https://www.ebay.co.uk/i/1716469042...3D710-134428-41853-0%26rvr_id%3D1463968138035
I would suggest you glue two and a half inches to each side. That way, any irregularity in texture caused by the glue/foam interface will be too near the edges to cause any discomfort.
I just used a heat resistant spray glue. Push together and pinch the surface where it meets to get a good contact. I went from 3/4 to full width no problem. I also glued the new scrim with it and the ends of the stockinette cover. Its been absolutely fine.
Go to a proper upholsterers that does camper beds or car headlining or boat headlining. . and buy a tin of their preferred high temperature spray adhesive. Or pay them to stick it together. Locally I use Totton Upholsterers for foam and sticking it and Hawke House near Lee on Solent for headlining and glues. One tip I got was if sticking foam to a flat surface was to use contact glue that you spread from a tin on the hard surface and the spray stuff on the foam.
That Red Trim-Fix stuff peeeeved me right off because I used it to trim my dash in leather, however after about a year in the heat & sun the glue became fluid again and unstuck. The Screwfix "Nemesis" contact adhesive is the best I have come across. All my door cards and seat foams all have been holding strong with this stuff.
Yep I agree craaaaap but the screw fix glue nemesis. thats what its called could rember it the dogs bollooooocks.
