I had a pipe freeze & burst during our foray into zero degree temps 2 nights ago. It was the cold water feed to an upstairs tub/shower. I looked in my crawl space and can see there is no insulation between the fiberglass shower unit and the exterior walls. But I'm thinking the coldest air likely came in from roof soffets from the crawl space under the gabled (sloping) part of my roof and one of the pictures shows how I can see the tub from the crawl space. I do not see how I can insulate between the shower unit and the side of the house because I just can't reach that area. But I can at least put some insulation and/or a block-off board to prevent the soffett air from reaching the tub. I only have access to the end of the tub shown which is opposite of the end with the water controls. And the silver pipe shown is my dryer vent pipe. Thoughts? This is new territory for me. This is what I can see from my crawl space access Close up of the shower unit showing the rectangular "cutaway" where the tub was left exposed to the crawl space. I'm thinking I can just block this off with a sheet of plywood cut to fit, although the shower wall will still be adjacent to the exposed/uninsulated exterior wall that I can not access to add any insulation.