Skinning and working 50mm extruded polystyrene foam insulation panels

[ian maybury]

I've projects to build cat accommodation and a drying kiln on the go and can't seem to source ready skinned weather proof insulation panels to build them from - only the basic styrofoam panels. Sheet metal skinned construction panels would be overkill, hard to work and very expensive. So the plan is to if possible skin panels myself.

Not too sure what to use for this purpose. Cheap, easily worked, ready finished, weatherproof, no unhealthy smells or fumes, 75 deg C plus temperature resistance, UV resistance and easily worked are requirements that come immediately to mind - might something like a thin weatherproofed ply, PVC plastic or formica like (but softer) sheet or signboard work?

Polyurethane (the foaming liquid type?) is usually listed as the recommended adhesive for styrofoam, but i'd rather use something like a contact type that can be rolled down and doesn't require heavy pressing. Longevity, heat and water resistance are problematical with most contacts though...

There's fasteners about with a very large diameter head and a large plastic screw that can be used to screw panels to each other (not the more common type used to secure insulation panels to walls etc), but no sign of a source or manufacturer coming up on Google.

Not too sure about shaping panels beyond using woodworking machines and a track saw either - maybe there are some convenient fixes/important considerations?

Thoughts anybody?

Thanks

[Mark Kornell]

The adhesive you want is Loctite PL300 or equivalent from another manufacturer. Meant for adhering foamboard to just about anything. It isn't a contact-type adhesive, but no heavy pressure required. Apply the adhesive to one of the materials, squish them together and let sit overnight.

I'll suggest fiberglass sheets for exterior use. Light, waterproof and reasonable cost. Not particularly UV resistant, but paint will fix that. Cuts easily with a jigsaw or bandsaw. Probably good on a table saw or with a circular saw, but haven't tried those. A rasp or file is handy for dealing with sharp edges.

[ian maybury]

Hi Mark, thanks for that. The adhesive looks like it could do the job. Amazed to see Loctite offering a relatively commodity product like that - not a hope back in the 80s when i worked for them when the motto was 'drop by drop'. They snickered at a product selling for only $60/kg - back then. They weren't awfully interested unless there was tons/year of business involved either. How times change, but actually a very healthy development. It probably originates with the Henkel side of the business.

I had a look locally for fibreglass sheeting, but it's very expensive here in Ireland - maybe €250 for an 8x4 sheet from the various refrigerated truck fit out and custom panel people offering it. Guess i was hoping to find something much more budget priced. Not much coming up though short of 4mm marine play and the like - but it's not confidence inspiring regarding weather resistance.

I'd hoped that maybe there might be some sort of foam board used for signage, but it seems expensive and may not be very long lived.....