ROOF Covering

Every inspector should be able to name the basic styles of  roofs.  In some cases it could be a combination of styles but nonetheless calling a gable a mansard or a hip a gambrel should be very avoidable. 

Each style of roof has different design characteristics and things to look out for.

Gable:  The gable roof is known for the squared off ends and steep slope.  The gable is one of the easiest roofs to design and build and when issues develop they typically occur in the valley where two or more gable intersect.

Hip:  The hip roof when placed on a house with  a very steep roof could most closely resemble a pyramid.  It will not have square ends but rather angles.  A hip roof by its deign should have an attic that has better ventilation due to the natural convective air flow.  Hip roofs are more complicated to build and will not have as many valleys as the gable roof.

Mansard:  The mansard roof is of French origin and the difference between it and the hip is the attic space is the finsihed upper level of the home.  The roof material is the siding of the uppermost floor.  There may be a small attic above the ceiling space but egress will be very limited.  One important item to look for in a mansard roof is the windows of the upper level.  They are typically built into the roof and have flashing or arches at the tops that must always be kept well sealed.  More water entry reports and situations occur at these windows then any other location of the roof system.  The upper small hip portion of the mansard roof will wear out a bit sooner then the siding portion of the roof.

Shed:  A shed roof is typically attributed to the addition of the home.  It is the easiest of roofs to construct and place on an existing structure.  Some home have originally built shed roofs but they are uncommon.  When inspecting the shed roof thoroughly review the flashing to verify it is sound and sealed.

Gambrel:  Gambrel roofs look like the bard style roof.  They are very common in a home style called dutch colonial.  Like the mansard roof it may have windows placed into the roof surface and reviewing the flashing will be important.  The Gambrel roof has all of the advantages of the mansard with the ease of construction of the gable. 

Butterfly:  Butterfly roofs are not very common but when inspected always leak down the center drainage channel.

ESTIMATED AGE

Asphalt Shingle Roofs

Asphalt shingled roofs with self sealing tabs are expected to lie flat with all overlapping ends fully sealed.  Although newly installed roofs may take a year to become fully sealed, this condition should then continue for at least ten years under normal conditions.

As the roofing material ages some wear signs will begin to appear.  Among the wear signs:

w          Corners will turn up;

w          Some shingles will begin to “cup” or curl;

w          Covering granules will be worn away;

w          Wear holes will become visible

w          The overlap ends will no longer be sealed.

When estimating the age of roofing, similarity to other roofs based upon experience is the most common denominator, but there are some other wear factors which should be taken into consideration.  Here are a few:

w          Asphalt shingles installed on steep pitched roofs will generally last longer and show less wear than those installed on shallow pitched roofs;

w          Heavier weight shingles will generally last longer than lighter weight shingles.  (Weight is one of the grading factors used in shingle descriptions.  A 235# shingle, the most commonly used, signifies that one hundred square feet of roofing material will weigh 235 pounds);

w          Shingles in roof valleys will wear much faster than those installed on a regular roof plane;

w          Some shingles, usually those of lesser quality, do not have self-sealing tab ends.  They are not a shingle or preference nor commonly used in modern day construction.

When reporting the estimated age of roofing, there can be nothing more accurate than historical evidence of it’s date of installation (usually the paid invoice).  This evidence, can on occasion, however, be the source of an inspector’s dilemma.  The purpose for reporting the estimated age of the roofing is not so much to report empirical data (although it is pertinent) as it is to give an indication of how much roof life is left.  The question “how old is the roof?” may give way to the more important question, “How long is it expected to last?”  The inspector’s estimate of age will depend on which question is being answered, or maybe the inspector needs to report both!

Newer roofs with signs of old age are prematurely failing and may require early replacement.  Some of the causes of premature roofing failure are:

            w          Inferior material quality;

            w          Faulty material manufacture (oftentimes covered by warranty);

            w          Improper installation;

            w          Inadequate ventilation.

Roofing replacement is not based upon age - it’s done when the roofing is worn out.  The inspector must therefor report what has been observed with special attention to the remaining roof life.  Here’s one example:

The roofing was (reported to be) installed six years ago, but it’s wear factor appeared to be about 14 years.  i.e. many shingle ends were turned up and the shingles in the valleys were much cupped and worn...

Wood shakes and shingles

Wood roofing will tend to rot, warp or split as it advances in age - especially if the shingles are not sealed.  They are also very susceptible to organic debris and damage.  If there is a low hanging tree or leaves allowed to decay on the roof it will greatly decrease the life expectancy. 

Years ago wood roofs were placed on a home and the life expectancy was over 30 years and in most cases 50+ years.  This was because they were not placed on a solid roof deck but rather a batten or spaced deck.  Form the attic you could see spaces between the roof deck and typically see the roofing material and sometimes daylight between the roof shingles or shakes. 

The difference between shakes and shingles is very simple.  A shake is split form the cedar.  It has a very irregular thickness and size to it and is not smooth in texture.  A shingle is cut and is regular in thickness as well and width.  Both will require the same amount of  maintenance and attention and wear at about the same rate. 

Older Style of Installation

Modern Style of Installation

When reviewing cedar roofs, be it shake or shingle they will both wear in the same manner.  Describing the type of wear or condition is important.  Here are three conditions that will be present.

Inspecting a Wood Roof

The best way to inspect a wood roof is by placing your ladder against the home and touching it.  In is not recommended that you walk many wood roofs.  If the individual pieces become loose, cracked, curled or worn they will give way under foot and you will either cause damage to the roof or your self when you fall of the roof.  The second and third best ways to inspect the wood is by using the window and touching the surface or with binoculars.  You should review all of the planes of the roof as well as the flashings.

Tar and other flat roof materials

Flat roofing materials are normally bonded to the roof deck.   As the installation ages, the bond will be compromised causing bubbles which sometimes contain trapped moisture.

Flat roofs should normally have not less than five years of reasonably imperceptible wear but such things as good water run-off will substantially extend roof life.  Correspondingly, ponding water will generally accelerate wear and take a toll on roofing material.

Tar roofing will crack and “alligator” as the material ages and all materials are subject to openings in the overlap ends as the roof becomes older.

Age of building as factor

A good inspector will take the age of the building into account as a valuable and necessary aid in determining the age of a roof-especially on asphalt shingled roofs.  A fifteen year old building with only one layer of roofing is most likely to have a 15 year old roof.  A 30-35 year old building is most likely to have been re-roofed at least once.  This rationale becomes more difficult to apply in much older buildings and may be otherwise interrupted by such things as new building additions, fire or other calamity and an incidence of previous roofing failure.

The inspector’s challenge for accuracy is first to apply simple logic and then take into account the many possible variables.  Simply stated: when reporting the estimated age of roofing, it all has to fit, somehow, some way.

Things to look for and check:

Asphalt shingles and rolled roofing:

w          Cross section or end view

w          Underside of existing (if feasible)

w          Age of building as factor

Concrete, clay or slate tile:

w          One layer normally installed

Tar, tar and gravel, various single ply:

w          Normally not ascertainable without cutting section of roof

Metal:

w          One layer normally installed on sloped roofs

w          Used as a flashing base for other flat roof covering

VARIATIONS IN ROOF PLANES

Each and every plane and ridge line of every roof section must be viewed and checked.  This is an extremely important part of every building inspection.

Checking the roof plane is a good way to assess the condition of the roofing and take notice of whether or not the shingles are sitting flat as they should be.  It  helps to see if the shingle ends are sealed, and take notice of cupped shingles, raised corners or loose nails.

A variation in the plane of a roof may be a sign of structural adversity.  Roof sections which bow downward can be a sign of bowed, cracked or otherwise failing roof rafters.  Sagging ridge lines too are a sign of possible rafter failure.  In other instances  it may be a sign of sagging or broken roof sheeting.  These important elements will have to be further inspected and analyzed.

Sometimes the variation in plane will be the result of original construction.  i.e. the roof structure may have been built that way.  Carpenters aren't always perfect.  Then when additions or dormers are installed there may not be a perfect match to the planes and lines of the original building.  Many times, in some of the older solid masonry buildings, the brick walls at a gable end made it very difficult to achieve a straight ridge line at or beyond that end.

Each and every variation in plane must be noted and it’s cause determined.  For the purpose or report writing, only those variations caused by irregularities of the roofing material (such as raised shingle ends) are reported under the heading “Surface Condition”.  Other variations related to structural aspects will have to be further analyzed and then recited in the structural elements section of the report (see “Deflection; Part III, Attics”).

When looking at the roof paying careful attention to all roof penetrations will be critical.  These penetrations include skylights, chimneys, flue stacks, vent pipes, dormers and valleys.

FLASHING

Whenever an item bisects a plane of the roof there is potential of leakage.  This intersection is typically protected with flashing.   Flashing has historically been made of metal and is placed against the house and married to the roof surface.  If there are two or more surfaces placed together or the area requiring protection requires additional sealant counter flashing is installed over the flashing.

The picture below illustrates how flashing is being used next to a chimney.

Flashing is also used where the house intersects the roof as shown below:

Dormer inspections can be very difficult because in most cases you are not going to be able to be on the roof and touch them.  Most dormers are installed on the second floor of a roof that is steeper then typical and beyond most inspectors walking comfort level.  These dormers must be flashed also.

There are several styles and types of dormers used in modern architecture.  Being able to call them by name is important for your knowledge but also to your clients.  Some types are:

Valleys

Most roofs will leak at the valley.  It is very difficult for a roof surface to just develop a leak in the middle of a plane without a cause or reason.  The valley carries all of the water, snow and debris form a roof to the drainage area.  This water travel will wear the surface and cause a need for attention sooner then the rest of the roof. 

There are two types of valleys:  Open and Closed.