Roofing failures are often blamed for many water intrusion and mold claims. Contractors often blame the roof and most homeowners simply do not know. Frequently, Cissell Investigative Engineering LLC (CIE) finds poor ventilation and/or insulation issues causing the problems. Our knowledge of roofing, HVAC engineering combined with thousands of investigations allows us to quickly and accurately determine the cause or often causes.
A claim we investigated was initiated by a new homeowner, the attic was a mess, heavy mold contamination on a newly installed roof deck, water was dripping from the shingle nail penetrations. The roof shingles were installed by previous owner the year before. Cause, inadequate attic ventilation. The roofing contractor was, in our opinion, responsible to inform the owner of the need, failure to inform is negligible.
Another claim found a converted cottage with an elderly couple using unvented propane and kerosene fueled heaters with extensive water dripping from the ceiling. The roof was nearly flat and recently shingled, CIE found evidence of some minor seepage through the roof due to ice dams, however, the saturation of the roof deck was extensive with frost and water dripping from everywhere. The unvented combustion was converting about 90% of its weight in fuel to water vapor!
CIE has also saved many insurers from needlessly replacing roofs and eliminating the problems with simple changes in ventilation or insulation. We have also found cases where the shingles are defective.
Common shingle roofing problems:
- Premature thermal cracking: Vertical cracks develop below and above butt edges of shingles. Shingles expand and contract with the climate. If the adhesive strength exceeds the matt strength, vertical cracks occur. A common mistake made is there is too much offset between rows. Too much offset reduces the number of rows of shingles between seams, causing less shingles to withstand the horizontal strain caused by the thermal movement. Result is a vertical crack prematurely occurring.
- High Nailing. Manufacturer’s recommend a specific pattern and location for the fasteners. The location is important as this is where the manufacturer tests against wind uplift and other storm related forces. A location too high causes the shingle to be less resistant to wind forces.
- Poor sealing. Edges and bottom of the roof need extra attention as these are the most vulnerable locations to wind. One common problem is too much overhang, using inadequate materials or materials not specifically designed for the application. If you can lift the bottom or edge shingles, it’s not properly sealed.
- Flashing defects. Flashing is intended to direct any seepage through the roofing shingles and off the edge of the roof. It is also used along the walls, chimneys and other penetrations to prevent water from backing up and under the shingle. We see caulk used liberally as a stop gap protection. Unfortunately, caulk has a limited lifespan and poor durability.
- Roof overlays with different sized shingles. Manufacturerls have recently gone metric and we are seeing overlays of standard shingles with metric, causing all kinds of problems with properly fastening the shingles. The top layer of shingles are becoming loose becasue the fasterners are poorly embedded and allow too much movement with storms, climate and other forces. The nails wear out the matt and cause damage to the shingles by rounding out the hole where the fasteners penetrate. With time these holes become large enough to allow the shingle to loosen and slip.
- Wear and Tear: Composite asphalt shingles exposed to the sun age and become more brittle with time. The aggegate cover becomes fragile and easily breaks off. When the aggregate breaks off, more of the asphalt is exposed to the sun and deterioration accelerates.