Measure the eave length and soffit width
Cut soffit panels to size
Install J-channel or F-channel along the wall and fascia
Attach receiving channels securely with nails or screws
Fit the soffit panels into the channels
Lock panels together if using interlocking soffit
Fasten panels to framing as needed
Leave proper expansion gaps for vinyl or aluminum soffit
Cut openings for vents or fixtures if required
Install vented soffit where airflow is needed
Check alignment and spacing as you go
Secure all edges and corners
Seal gaps if required by the material system