How to join foam?

[Dougget]

I now have a layout plan that is larger than 4x8. So one piece of foam is not going to do the trick. What is the best way to join the foam and hide the joint?

I was thinking about using a 'biscuit' technique using pieces of lauan or something to reinforce the joints. Gluing everything together with latex caulk.

Is there a better way?

Thanks,
Doug

 

[diburning]

the biscuit method works, although if you are very careful with styrene cement, you can chemically weld the foam together.

 

[Trucula]

Liquid Nails works well and also they actually make a foam board glue. Name slips me now but I saw it at Lowes. Spackling for the seams. Also I searched foam board glue and found this:
http://site.iwebcenters.com/afoammart_2/foam.html

 

[eTraxx]

 

[kenw]

so i am assuming you are talking about joining edges of multiple foam sheets (each less than 1" thick)? even if you have a wood frame, the foam joints should be reinforced if the foam is not laying on a wood deck.

I would not rely on any adhesive alone, especially if tracks cross the joint. I would definitely place (glue, screw or otherwise) a thin wood panel under the joint (?5-6" wide, so that 3" is under each sheet) as reinforcement. 1/8" masonite or scrap Luan would more than suffice.

all imho, of course.

 

[UP2CSX]

I agree with Ken on this, if you are trying to bridge two pieces of foam with no other support. Foam without support will almost certainly fracture the first time it meets an inadvertant elbow. plain latex caulk works fine for me as an adhesive, although Liquid Nails for Projects will work well if you already have some on hand. I use wallboard tape and mud for the joints. Sand it down when it's dry and the joint will disappear.

 

[Beachbum]

I use a splice plate of Masonite glued under the joint if the foam is not laminated to some kind of wood deck.