Measure the shed walls, roof, and floor
Choose insulation type: fiberglass batts, rigid foam board, spray foam, or mineral wool
Seal air gaps and cracks with caulk or expanding foam
Install a vapor barrier if needed for your climate and shed use
Fit insulation snugly between wall studs and roof rafters
Cut rigid foam boards to size and secure them in place
Tape seams between foam boards with insulation tape
Insulate the floor with foam board, batts, or underlayment if accessible
Cover insulation with plywood, drywall, or paneling for protection
Insulate the shed door with foam board or weatherstripping
Add weatherstripping around doors and windows
Insulate windows with shrink film or interior storm panels if needed
Check for ventilation to reduce moisture buildup
Inspect the shed for drafts after installation
Wear gloves, mask, and eye protection during installation