Feb 20, 2017
One of the most commonly asked questions that we receive from buyers regarding their home purchase concerns the condition and life expectancy of the roof.
The following discussion is intended to help answer general questions regarding residential roof surfaces in Rochester.
The great majority of roofing on residential structures in the Rochester area is Asphalt Shingle. The roofing actually consists of an asphalt based material that often contains fiberglass. The surface of the shingles is coated with granular stones that give the roof color and texture, while protecting the base material. For many years the general anticipated life expectancy of an asphalt shingle roof was approximately 20 years. Depending on wear factors, this meant that roof surfaces were typically replaced anywhere from 15 to 25 years after installation. In more recent years, higher grade roofs (some of which are commonly referred to as “architectural grade”) have become more the norm. These roofs are advertised as having 25, 30 and sometimes 40 year life expectancies. Again, depending on wear factors, this does not necessarily mean that they will last that long.
I have often explained to buyers and homeowners that as shingles age they do the same types of things that a leaf does in the fall, at a slower rate. Specifically, the roofing slowly dries, shrinks, curls, cracks, etc. The following four photographs clearly show the progression of roof wear. As you can see, the shingles in the first photo are laying flat, the surface is not deteriorated and the spaces between the shingles are narrow. In the next photo, the roofing is older. The spacing is wider, and the shingles have begun to curl. The third photo shows a roof that is clearly old and worn. The shingles are quite curled, the surface is very worn and shrinkage has resulted in wide gaps between the shingles. Lastly, the final photograph shows a roof that is extremely worn and poor.
Low Pitched Roofs
Speaking of pitch, Asphalt shingle roofs rely on pitch or slope to drain. Roof surfaces that have a lower pitch are more likely to experience leakage. Roofs with a slope of less than 3/12 (3 feet of rise for every 12 feet of horizontal run) can be especially prone to leakage with asphalt shingles. For this reason, alternate roofing materials are encouraged, or even necessary. Roofs that have a pitch of less than 2/12 should not be covered with shingles. Rolled asphalt is an alternative, but it is not the material of choice for low pitched or flat roofs. Instead, good quality membrane roofing is strongly encouraged. Such roofs should be installed by qualified specialists who are familiar with this type of roof. The following picture shows a rubber membrane roof.
One must be mindful that roof warranties tend to be limited. It is our experience that they oftentimes only apply to the homeowner who purchased the roof (they may not transfer to a future owner). Also, they tend to lose their value quickly. In other words, a “30 year roof” that fails after 15 years does not necessarily result in a 50% refund on the cost of materials. Also, most homeowners don’t realize that if their roof has been installed as a third layer or if the attic is not properly ventilated, the warrantee from the shingle manufacturer may be void.
Number of layers
For years the general practice in this area “allowed” for as many as three layers of roofing at a given time. Four layers were not unusual. The building code did not specify a maximum number of layers. That has changed. 3 years ago the New York State code was revised. It is no longer permissible to apply a third layer of roofing on a house. There can be no more than two layers. Also, it is not permissible to install a layer of asphalt shingles over wood shingles.
Many houses in the Rochester area that were constructed prior to around 1940 still have the original layer of wood shingle roofing. Whether wood shingles are still present in an older house can be easily determined by looking at the bottom of the roof from the attic. If there are wood shingles when a new roof is needed, it becomes necessary to remove all existing roofing and re-sheath (install plywood sheathing) the roof prior to the installation of the new roof. This can be costly. It is not unusual for roofing contractors to charge $300 - $400 per square for these jobs. A “square” is 100 square feet of material. An average house might have 20 – 30 squares on its roof. As you can see, these roof jobs cost many thousands of dollars.
Mother Nature can sometimes be cruel to us in the winter. Ice dams can result when we experience long periods of sub freezing temperatures along with frequent snow falls. The absence of a few periods of thawing temperatures during the winter months allows for ice and snow to collect on roofs, mostly on the roof eaves. The winter of 2003-2004 was especially troublesome. Low pitched roofs (and especially valleys) are more prone to ice build-up. This ice eventually creates a “dam”, preventing the roof from draining. Water will then back up under the roof, causing leakage. Even a roof in very good condition can experience leakage from ice damming if the conditions are right, OR WRONG! Providing proper insulation and ventilation in the roof can greatly minimize the possibility of ice damming. For this reason, homeowners should not “skimp” when roof replacement is undertaken. The proper steps should also be taken to provide good ventilation. Also, “ice and water” shield should be utilized under the roofing in potentially troublesome areas. This is a continuous barrier of rolled material that is placed on the roof, beneath the roofing.
Alternate Roofing Materials
Slate, Mission Tile, cement tile, Wood Shake and Metal roofs are also scattered around the Rochester area. These are specialized roofing materials which can provide decades of dependable life. Slate and Tile roofs can last for many generations if maintained properly. They require periodic repair and regular maintenance and they are expensive to install. Having an experienced roofing contractor regularly (annually) perform inspection and repairs can prolong the useful life of these roofing surfaces. These specialized types of roofing are often the material of choice for Rochester’s more architecturally significant houses from years past.
I trust that this relatively brief summary of roofing provides some beneficial information for you to use in your day-to-day business. As is always the case, please do not hesitate to contact our office if we can answer any questions for you or be of any assistance. We stand ready and willing to provide you and your clients with the best home inspection and consulting service in Rochester. Also, please feel free to suggest future topics for our Newsletter.
Douglas J. Burgasser, P.E.
NYS Licensed Professional Engineer, NYS Licensed Home Inspector