No universal winner
Compare insulation in the same assembly, under the same conditions.
These are conditional decision matrices, not product rankings. Repairability, drying, access, and skill matter too.
Spray Foam vs Cellulose: Air Sealing, Depth, Drying, and Retrofit
Compare spray foam and cellulose for attic, wall, and retrofit assemblies by air control, density, depth, moisture, access, and installation process.
Read the guideSpray Foam vs Fiberglass: Compare the Complete Assembly
Compare spray foam and fiberglass by air control, installation tolerance, drying, repairability, fire covering, thermal bridging, and access.
Read the guideSpray Foam vs Rigid Foam Board: Continuity, Joints, and Repairability
Compare spray foam and rigid foam board by continuity, thickness control, seams, substrates, vapor behavior, fastening, fire covering, and future access.
Read the guideA useful next step
Turn the reading into a plan.
Answer seven practical questions and see which conditions to investigate before choosing a material.