XPS insulation is extruded polystyrene rigid foam insulation. It is commonly sold as foam board.
Why It Matters
Rigid foam insulation can affect thermal performance, moisture behavior, siding details, window depths, and exterior trim transitions.
Common Problems
Common issues include poor seam detailing, wrong fasteners, trapped moisture, incompatible materials, and not planning trim or flashing depths around the added foam thickness.
Building Codes & Industry Standards
Rigid foam insulation should follow local code, energy requirements, fire-safety requirements, and manufacturer instructions for the assembly.
Exterior Echelon Notes
Exterior Echelon considers rigid foam as part of the overall building envelope, especially when siding, windows, and exterior trim are involved.