RobRing
New Member
Our master bathroom is located over our unheated garage, which means that all of the water supply lines and drains are over the garage also. We live in Rochester, NY, which is known to get chilly now and then. It’s a half-assed design, but it’s surprising the things you don’t notice when you buy a house. The floor joists are 2X10 and the joist cavities are filled with fiberglass batts. The supply pipes are also wrapped with black foam insulation, perhaps an inch thick. It’s all enclosed by 1-inch rigid foam 4X8 sheets and covered with drywall. The pipes have only frozen once when I left the garage door open for several hours on a sub-zero degree day. Nevertheless, I’ve never been happy with the design (not only are the pipes at risk, but the bathroom above is notably colder than the rest of the house).
I’m re-insulating the garage ceiling / bathroom floor with closed-cell polyurethane spray foam, but the supply pipes are an issue. They are located about 3 1/2 inches from the bottom of the joist. Currently the only insulation between them and the garage is the pipe wrap, 3†of fiberglass and 1†of rigid foam. Theoretically they benefit from residual heat loss radiating down from the room above – whatever makes it through the 6†or so of fiberglass above the pipes. If we foam the bottom of the subfloor (3-4†thick) we isolate the pipes from any residual heat from above. Even if we re-wrap the pipes , surround them with fiberglass, and reinstall the foam-board under the drywall I think we’re still a little worse off than before, at least as far as the pipes are concerned. Would we be better to box in the supply pipes with plywood – essentially creating an un-insulated void space between the pipe and the bathroom floor – and spray-foam the space between the bottom of the pipe and the ceiling? Or is the residual heat theory bunk? Are their other options we should consider? Or, since I have full access to the pipes from below should I cut them and shift them up closer to the floor? I’m not a fan of creating new penetrations in my joists, but perhaps I can sister them to compensate. Bottom line is I don’t want frozen pipes but I do want a better insulated bathroom floor (and a stable floor also).
Thanks!
Rob
I’m re-insulating the garage ceiling / bathroom floor with closed-cell polyurethane spray foam, but the supply pipes are an issue. They are located about 3 1/2 inches from the bottom of the joist. Currently the only insulation between them and the garage is the pipe wrap, 3†of fiberglass and 1†of rigid foam. Theoretically they benefit from residual heat loss radiating down from the room above – whatever makes it through the 6†or so of fiberglass above the pipes. If we foam the bottom of the subfloor (3-4†thick) we isolate the pipes from any residual heat from above. Even if we re-wrap the pipes , surround them with fiberglass, and reinstall the foam-board under the drywall I think we’re still a little worse off than before, at least as far as the pipes are concerned. Would we be better to box in the supply pipes with plywood – essentially creating an un-insulated void space between the pipe and the bathroom floor – and spray-foam the space between the bottom of the pipe and the ceiling? Or is the residual heat theory bunk? Are their other options we should consider? Or, since I have full access to the pipes from below should I cut them and shift them up closer to the floor? I’m not a fan of creating new penetrations in my joists, but perhaps I can sister them to compensate. Bottom line is I don’t want frozen pipes but I do want a better insulated bathroom floor (and a stable floor also).
Thanks!
Rob