walls greater than 4x8?

[GSP848]

Hey, My idea for a camper is one with side walls 10' long and 5' high but foam sheets are only in 4x8' so I was trying to figure out how to join an extra 2 feet to the existing piece. I was thinking of maybe cutting the pieces to interlock kind of like big jigsaw puzzle pieces and glue the seams together as well and then PMF over all of it. Then on the inside using paneling and just make sure the seams in the paneling don't line up with the seams on the foam. Would that work? Has anyone ever made a foamie of a similar size and how did you do it? Thanks!

[QueticoBill]

Since the strength of pmf is the fabric skins,v I believe a simple spline joint (tongue and groove like) will suffice. Maybe just glue square edges.

[Pmullen503]

The walls on my foamy are 10 feet long, so I added 2 feet. Splines are exactly the way to go. Mostly to line up the edges while the glue dries. I clamped with rope and wooden cauls to protect the edges.

Another tip: the joints won't be perfect so you want to sand the joint flush. Be careful to keep the glue away from the surface of the joint. The glue is harder to sand than foam so the joint will more obvious after sanding. You'll want to carefully trim off any glue squeeze out with a razor blade before sanding.

[GPW]

Considering that the strength of the wall is not the foam but the covering , it seems fine that a simple Butt joint would work . The foam will let go before the glue joint will ...so is essentially "one piece" after being glued together ... No worries !!!

[KCStudly]

My foam came with a cove and bead edge. Where I had to butt cut edges I just glued it with GG. A spline would probably been good (I had at least one joint where the foam thickness wasn't equal, so had to sand some. 2nd that the foam sands easier than the glue, so mask well, shave as noted, and try to avoid miss matches if covering with fabric (... if concerned about finished appearance). Rather than a spline, you could probably just butt and stick some bamboo skewers through the joint at oblique angles to lock it up. If the skewers don't pull out easily just trim them slightly below flush and fair with filler.