Roof Components

The roof consists of the structural deck (plywood or Oriented Strand Board) and roof coverings, (shingles). The visual inspection evaluates the deck for structural stability, the coverings for overall condition and life expectancy, as well as any protrusion through the roof, i.e.. plumbing vent, chimney, or skylight. The approximate age of the roof covering is based on the age of the house and the visual condition of the coverings at the time of the inspection.

The Inspection

Whenever possible, the inspection is done while walking on the roof. Some roof coverings, such as asbestos cement, tile, or slate may be seriously damaged if walked on. A steep pitch or inclement weather may make the inspection hazardous. In these cases, the visual inspection is conducted from the ground with binoculars and from a ladder at the edge of the roof.


It is often difficult to determine the source of roof leak. A water mark on the ceiling does not necessarily mean that the leak is directly above. The usual sources of leaks are faulty or deteriorating valleys and flashing. Once the source is identified, repair is generally a simple task. Areas where plumbing and flue pipes penetrate the roof are of particular concern. These roof penetrations must be properly flashed. Here is an example of a properly installed plumbing vent:

Multiple Layers

Local building codes may dictate the number of layers of roof coverings permissible. By most standards, the maximum is three. Multiple layers of shingles make it more difficult for the roof system to get rid of heat and will generally cause the shingles to have a shorter than expected life span. It is best to remove old shingles before installing new ones.

Roof Type                            Life Expectancy

Asphalt Shingles                 15‑20 years

Asphalt‑Multi‑Thickness     20‑30 years

Asphalt Rolled Roofing      10 years

Built‑up Roofing                  10‑20 years

Wood Shingles                    10‑40 years

Clay Tiles                              20‑30 years

Cement Tiles                                    20‑30 years

Slate Shingles                                  30‑100 years

Asbestos Cement Shingles           30‑75 years

Metal Roofing                                  15‑40 years


The chimney vents smoke and products of combustion produced from fire places and heating units. In order to prevent downdrafts, chimneys should extend up through the roof  to a point that is above the ridge. Generally accepted standards require chimneys be at least two feet higher than any part of the roof within a ten foot radius horizontally.

Masonry Chimney

Chimneys made of brick or stone and mortar are generally called masonry chimneys. They require annual inspection and maintenance. Tuck pointing is a term used to describe the repair of mortar joints. A masonry chimney should be built on its own foundation and may be enclosed within the structure or along side the house with one face next to the house.

Flue Liner

In the center of most masonry chimneys is a flue liner. The flue liner is generally made of ceramic tile and is designed to keep corrosive gases from deteriorating the mortar joints of the chimney. The flue liner should extend up to point higher than the chimney and utilize a chimney cap to protect the chimney from rain. Since the flue liner runs the entire length of the chimney, it is nearly impossible to visually inspect the entire flue. It is recommended that a qualified contractor inspect and if necessary clean the chimney annually, particularly in homes where a fire place is used. There may be multiple flues in one chimney.

Metal Chimney

Many fireplaces, furnaces, and water heaters utilize a metal chimney to vent smoke and gases. These chimneys are generally concealed in a “chimney” made of the same construction material as the home, i.e.. wood frame and vinyl siding. These chimneys must be installed with proper fittings and certain clearances must be maintained in order to prevent accidental fire. Metal chimneys used in wood burning fireplaces should be inspected and cleaned annually.

No Chimney at All.

Although it is uncommon today, it is possible that a home may have no chimney at all. With the introduction of the high efficiency furnace and power vent chimney, PVC pipe may replace metal, brick, and mortar. These plastic chimneys often terminate outside the house just above the basement wall. Electric water heaters do not require a chimney.

One Response to “Roof”

  1. Andrew says:

    Such a detailed blog, I’m so into this kind of article, I love reading blogs/article that is very educational and useful in daily life, I hope you still keep on writing topics like this. Thanks! I’ll look forward to it!

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