Thermal break?
GBA Editor
| Posted in Energy Efficiency and Durability on
Remodeling a bathroom in Michigan — 3’x5′ shower, two walls of shower are exterior walls, wall composition is vinyl siding, 1/2″ foam board insulation, 1/2″ sheathing, 2×4 studs w/ 3-1/2″ batt insulation. New cement board and new tile to be put on walls and drypack pan with stone shower floor. What can be done to provide a thermal break so that in the winter the walls and floor will not be ice cold? Thanks.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Greg,
If you've only got 3 1/2 inches, the answer is clear: closed-cell spray polyurethane foam.
You could also surround the exterior shower walls and floor with styrofoam, I use foam under tubs and shower units with a thin mortar base for strength.
Combine answers #1 and #2 and you've got what you're looking for.
The spray foam will maximize the R-value of the stud cavities but not create a thermal break. The XPS foam board on the floor and walls will add R-value and offer a thermal break over the framing as well as reduce the air and vapor permeability of the assembly.