Building panels resistant to fire and vandalism 2

[briggs22]

I am considering designs for light weight building exterior wall panels which will resist concerted efforts of vandalism and arson. Weight restrictions preclude masonry. Have considered metal plates to resist impacts, mounted on corrugated venting layer for shock absorption. Also considering completely metal structure with noncombustible insulation and interior wallcovering. I have not found anything manufactured which can resist impacts followed by burning fluids. Does anyone here have ideas or experience which may be helpful? Thanks in advance.

 

[civilperson]

Insulated wall panels have stainless steel or baked enamel finish with 3 1/2 " of polyurethane insulation sandwiched in the interior. Lock together with patented hook system and can span 10-12 feet for 90 mph wind loading. Variety of manufacturers but pricey.

 

[valleyboy]

How about a timber studwork frame, exterior lining of marine quality ply, with expamet covering and sand/cement render?

VB

 

[briggs22]

Thanks for your ideas!

Polyurethane foam-core panels may not delaminate after many impacts, but may not respond well to extended exterior burning.

I have tested 1-inch exposed-aggregate hard stucco over expamet, and even without sheathing support it does stay together under sledgehammering and should resist burning for an hour or so, but is by then pretty much destroyed and must be elaborately repaired to resist further damage.
Have also tested heavy guage flat sheet metal with 1" OC perimeter nails over hard sheathing, which is tough enough to discourage abuse, and heavier plywood would resist heavier impacts, but the sheet metal provides only a little burn protection, so I think the impact resistant layer needs to be noncombustible and resistant to chipping.

One concept uses upper wall shutters which hinge down over the entire lower wall to expose noncombustible finish siding over the entire wall. With shutters up, the exposed back surface and lower wall is vandal resistant and may sustain cosmetic damage without requiring repair. But it must remain intact for many damage cycles to be cost effective.

 

[briggs22]

Have now tested Alcopanel, a 4mm laminate of noncombustible polyethylene between thin aluminum sheets, and following hammering with a 3/4 plywood backing it retains remarkable fire resistance, beginning to delaminate at the edges after 15 minutes of propane torch. The aluminum does not melt in this test, and neither the plywood backing nor the paper label on the other side of the panel are charred. But while hot the core is soft and the material is easily punctured with further hammering.

In comparison, Cempanel fractures fairly easily under hammering and chars through in 5 to 10 minutes under propane torch.