Modern building materials in vintage restorations

[bredlo]

This may have been covered, I didn't to a thorough search.

As I'm looking down the barrel of a full frame-off restoration of a '63 Globe Trotter, I'm wondering about floor materials, insulation, etc.

The first thing that everyone says when you're considering an older model is to check the floor for rot. Another big problem is the insulation, especially in the belly pan where I hear it crumbles and compresses after decades of service.

It makes me wonder if there are modern alternatives to consider when replacing my floor and all insulation in the walls, etc.

First: Sub-flooring materials Aren't there formed, recycled plastic alternatives to 5/8" plywood by now? I'm aware of backyard decks which use 2x4's of recycled milk jugs rather than lumber. They look like wood, drill like wood, and never rot! Wouldn't this be a great alternative to plywood flooring, if weight was comparable? Even lightweight MDF which doesn't expand/contract in weather and is naturally more unlikely to rot would be better, no?

Second: Insulation I've seen half a dozen episodes of This Old House which uses a new kind of spray on foam insulation rather than the old "Pink Panther" Corning stuff. If one's inside skin were already off, wouldn't it make sense to spray on this stuff, which is superior to the old insulation in it's:
• heat retention
• flexability to move with the structure
• ability to seal out air leakage better than others
• completely non-toxic to the environment
• I imagine it wouldn't be prone to mold sitting in the belly pan like paper-backed fiberglass probably does.

There used to be a problem where this stuff would burst out of walls, etc. But newer kinds are slower to activate and don't create as much pressure on the walls, so one wouldn't need to have nightmares of rivets popping off and aluminum sheets flying across their backyard.

Just some ideas I'd like to bounce off everyone before beginning restoration. Lightweight, rot-proof alternatives to the stuff available in 1963 makes good sense to me, and would be appreciated by someone who didn't have to do it over again in another 40 years!

Brad