Is your porch sinking? Sometimes porches sink causing the columns and roof to sink as well which can lead to serious structural problems. This is a typical situation where the porch has settled about 4″ over time.
The bottom of the columns have rotted out causing further loss of support and the threshold step has pulled away from the door causing a large crack. The customer had not had jacks installed under the columns to keep the roof level so the roof sunk as well.
These conditions caused the porch roof to pitch outward creating a lot of stress on the front wall of the home. This resulted in cracks in
the siding materials which can allow water, pest and vermin entry into the home.
You can see from the picture below the pitch of the roof and the rotting column bases that contributed to the over problems. The columns had to be removed, a new porch poured and new columns installed after the roof had been jacked back up into a level position.
If you look closely 
at the picture on the right you can see the cracks in the trim abutting the home. This is where the most stress is and as a result where the cracking occurs.
