Asphalt Shingle Roof Defects

Roof defects are often a surprise to home owners.  It is an area of the home that is seldom thought of or looked at unless there is a problem.  Roofs in Montana are put to the test with high wind, extreme cold, extreme heat, dryness, harsh sun hail and rain. It is the intense sun and dryness that really take its toll. UV damage and drying out of the tars that hold the asphalt shingle together are major factors in premature shingle failure. The following are examples that I have found of common defects.

Here is a shingle roof from 1977.  It is 40 years old.  This one is a no brainier and was no surprise to anyone that it is bad.  It probably needed replaced about 20 years ago.  The roof now leaks in several places and water is showing itself on the interior ceiling.  These pics give you an idea of what happens to a roof if not replaced when it should be. These shingles are simply worn out with missing shingle stones, missing shingles, cracking, and curling.

Extreme Roof Wear
Worn roof found during inspection
Roofing beyond its years

The next picture is one you don’t see to often.  In this picture the framing or sheathing is pushing up the shingles.  This roof was relatively new but this area will likely age quicker as the shingles are under stress along this line.

high rafter showing

The next picture may be hard to see but that is exactly why it catches owners off guard.  Excessive shingle stone loss and where on the edges of the shingle.  At this point the shingle will age rapidly as the fiberglass fibers and asphalt are being exposed to the elements.  The shingle is becoming thinner and more brittle.

Shingle stone loss

The following pictures show what happen when shinlges have been abraded.  In this case this roof is in a high snow area where the roofs are periodically shoveled off.  The impact of snow removal tools creates spots that where and degrade quickly.  This roof also suffers from excessive shingle stone loss.

Wear from tool impact and age
Wear from tool impact and age
shingle abrasion and wear from impacts

Missing shingle tabs are another defect that can go unnoticed esecially on a high roof that is hard to see from the ground.  This creats a direct path for water entry  into the home as the roof barrier has been disturbed. The following are pictures of  missing shingles.

broken shingle tab exposing the fasteners
missing shingles
missing shingles

The following picture is something we don’t see very often in Montana.  Algal growth on a roof can happen here when the right conditions exist.  In this case this was a north facing wall with a west facing roof slope butting up to it. It was also shaded from a west facing wall.  There were many tall trees around the house as well.  Moss or plant growth can damage siding and roofing by getting behind the protective layers and drawing moisture into these spaces.  The can also physically lift and push, breaking the shingles.

algal growth on a roof

Some roof defects are easier to see from the attic!  The roof may appear ok from above.  The following are a couple of examples of roofs with issues seen from underneath.  The fist example was a roof truss that had experienced continual wetting and had severe rot and mold as a result.  The flashing on the roof was not sufficient to keep the water out because of a poor design on the roof.  The second example is actually a metal roof where the screws were misplaced, causing water to leak into the attic around the screws.

Defect found during home inspection
Rotten Truss
misplaced screw with water leak

Having a roof inspection is a vital part of a home inspection.  It is also important for any home owner to conduct one periodically to ensure the roof integrity and make necessarily repairs and replacements.  In this way the longevity of the roof can be ensured. Call today for a home inspection