Ken Basden, P.E., S.E., Structural Engineer
Case Description: A structural engineering opinion was requested on a residential storm damage claim referencing “damage sustained to the rear porch of the property causing separation at the rear door, wall and rear window.”
Upon arrival to the site, a wide crack in the masonry veneer at the rear porch was observed. The crack was in a horizontal mortar joint about half-way up the wall and extended from the door frame to a nearby window.
The general structural condition in the vicinity of the rear porch was then documented. During documentation, it was observed that the brick veneer had also separated from the bottom of the porch door and the bottom of the porch window. Furthermore, there was a gap at the bottom of the wall between the brick veneer and the porch slab. Out away from the wall, a crack in the porch slab was also noted. The crack ran full length across the porch.
Expert Analysis: Based on observations, it is opined that the damage to the brick veneer and porch slab is due to downward movement of the porch slab relative to the main structure. When the brick veneer was constructed, it was built on top of the porch slab and tied to the stud walls. As the porch slab moved down relative to the main structure, it pulled away from the bottom of the brick veneer. The weight of the unsupported brick imposed vertical tension stresses in the veneer, and the stresses were relieved at the mortar joints. The horizontal mortar joint crack between the porch door and window, the separation of the brick from the bottom of the porch door, and the separation of the brick from the bottom of the porch window were all caused by downward movement of the porch slab relative to the main structure. The downward movement also caused the crack in the slab out away from the wall.
Confirmation of a storm in the area on the reported date of loss was noted; however, the maximum recorded sustained wind speed and gust speed of 18 mph and 35 mph respectively are well within building code requirements. It would require significantly higher wind speeds to exceed the presumed allowable masonry stresses. The damage to the brick veneer was unrelated to the storm.
Ken Basden, P.E., S.E., Structural Engineer with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.