Perhaps the most prevalent complaint of leaks in community associations are related to improperly installed roofs. There are two main roofing systems utilized for residential construction. Namely, asphalt shingle roofing and flat roofs. In this segment, I will discuss the proper way to install asphalt shingle roofing and the problems that result from failing to install a roof properly.
Perhaps the most frustrating part in dealing with roof leaks is the realization that installing an asphalt shingle roof is perhaps the easiest stage of construction to perform properly.
Ideally, shingles should be installed at temperatures ranging from 40 to 85 degrees Fahrenheit. Shingles become brittle and crack easily when installed in cold weather. If installed above 85 degrees, the shingles become too pliable and will tear or the granular surface mars too easily.
The first step in installing a shingle roof system is to install the proper underlayment (ice shield) and drip edge. The roof deck should be checked to ensure that it is sound and level without gaps before installing the underlayment. Fifteen pound felt is required by code in some areas. Whether or not it is called for, the underlayment is cheap insurance against water intrusion problems because it provides an extra barrier in case of shingle blow offs or water penetration through the roof flashings. At the very least, the underlayment should extend up the roof line 36 inch from the interior wall line due to the amount of ice and snow buildup in New Jersey. Drip edge should always be used along the eaves to kick water away from the fascia and rakes.
Once the underlayment and drip edge is installed, a starter course of asphalt shingles with the tabs removed is nailed along the eaves so the sealant strip seals down the first course. Successive courses should then be offset 6 inches (half the tab) on a 36 inch shingle in a stepped fashion. This allows the cutouts to align every other course and the butt joints align every seventh course. This overlapping pattern is followed to effectively resist leakage.
Unfortunately, in this day and age, roofers tend to install shingles straight up the roof with a half shingle offset causing butt joints every other course. This is referred to as “ladder style” application and is not recommended by any shingle manufacturers. This installation results in a less watertight roof allowing wind driven rain to penetrate leading to wide spread roof leaks in storms or on roofs that with exposures to wind.
Shingle nail placement should follow manufacture specifications which typically require nailing just below the seal strip. Nailing the roof shingles too high can cause wind to get under the shingles resulting in blow offs. Nailing the shingle too low will expose the nail to weather. Nailing the shingle through the sealant strip can interfere with sealing. Furthermore, standard shingle nailing for three tab shingles is four nails per shingle-about one inch in either end and one over each slot. It is not uncommon for roofers to only use three nails per shingle resulting in blow offs. Failure to properly nail shingles frequently results in pervasive roof leaks.
If the shingles were improperly installed and/or nailed, the only permanent repair is to tear the shingles off and install new shingles the proper way.
Flashings for asphalt shingle roofs should be corrosion resistant metal and installed by roof wall intersections. Flashing is called for in multiple locations-around chimneys, crickets, valleys, etc.
However, the most common roofing related water damage we experience in representing associations is when roofers fail to put in “step flashing” along a roof-wall intersection. “Step flashing” should be installed in homes that are configured where a sloped roof intersects with a flat roof (the most common occurrence is where the garage roof meets the wall of the home). The last piece of a step flashing system is referred to as a “kick-out” or “diverter”. This simple piece should be install where the roof wall intersection ends by the gutter. The purpose is to take the rain fall that runs down the roof and step flashing and divert it away from the wall. The part costs less than five dollars. Unfortunately, the failure to install the kick-out properly, if at all, has resulted in millions of dollars of damage because water overflows the gutters as a result and gets behind the building façade causing wood rot and mold.