Years ago I read somewhere about a building material described like this :
- a composite/synthetic material (not wood)
- available in traditional dimensional lumber sizes (e.g. 2x4)
- rigid enough to have roughly the load bearing capabilities of lumber
- allows drilling and using fasteners in much the same way you would lumber
- has a high R-value (more insulating than wood)
- likely patented and manufactured by a single manufacturer (as opposed to more generic technologies like fiberglass or polyurethane foam)
I've since tried to find out what it was but without luck.
My use case is to modify a chest freezer by adding a "collar" between the lid and the chest to allow for running beverage lines into the chest freezer. This is a common DIY project for homebrewers called a "keezer". Here's a photo of a typical example.
Often the material used to build this collar is dimensional lumber, which the builder then adds insulation to the inside of. I'd like to find out what this alternative building material is that I'd read about in hopes of using it instead.