What is the best type of insulation for ridged duct in an unconditioned crawl space with conc. slab floor? Is 1-1/2 " foil backed sufficient?
insulate the crawl walls -- including over the vents.
2" Styrofoam works well
harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!