I’m agonizing over what to use under my metal roofing. I need something that will lie over my two layers of foamboard to take screws for attachment to rafters and also something to attach my exposed fastener metal panels to.

I’d like to avoid adding another 1.5″ using 2×4 but most furring strips I’m finding are total garbage and only come in 8′ lengths. Originally, I had planned on using 1/2″ OSB or plywood, but that will be very expensive and wont allow me to shim out any sags easily. I wish there was some affordable synthetic material I could use.

Any preferences for a strapping method here?