Welcome to the Inspection Insider. Here, seasoned home inspectors share their technical expertise and experience to help you improve your own inspections.
In this post, Uli Sommers of Sommers Home Inspections in Oregon discusses premature roof failure. Since 2013, Sommers has applied her two-decade remodeling background as a residential home inspector. She has served in multiple inspector organizations, including the Oregon Association of Home Inspectors (OAHI), the ASHI Education Committee, and the Examination Board of Professional Home Inspectors (EBPHI). Sommers also appeared on the Structure Talk and Nancy MD podcasts to discuss being a woman in the male-dominated inspection industry.
Now, here’s Sommers with her article on premature roof failure.
With the rising cost of a roof replacement, performing a thorough inspection is extremely important. Your inspection findings can motivate clients to negotiate repairs or budget for a replacement. Many insurance companies also want to know the roof’s condition.
In my area of the Pacific Northwest, most homes have architectural shingles. There are multiple reasons why shingled roofs fail prematurely. From personal experience, there are four main factors:
Let’s take a closer look at each of them.
Proper ventilation is key to a healthy environment both in the home and on the roof. In his book “Moisture Control in Buildings: The Key Factor in Mold Prevention,” author Heinz R. Trechsel explains:
“The average family of four generates between two to four gallons of water a day through activities such as cooking, cleaning, showering, laundry, and breathing. Some of this water vapor rises into the attic. Ventilation helps remove it before it causes problems such as wood rot, wet insulation, mold, and mildew.”
Extensive exposure to high moisture levels eventually leads to delamination and deterioration of the sheathing. This will not only require a roof replacement, but also the replacement of the sheathing, which adds a substantial amount to the cost.
While the exact calculation is beyond the scope of a home inspection, it is important to check for signs of inadequate ventilation and insulation—both in attics and crawlspaces. Obvious signs of problems include:
Let’s elaborate on what causes roof damage problems like these.
One common factor that contributes to premature roof failure is missing insulation in the attic. This can easily lead to condensation issues due to warm air rising from the living space below.
The attic ventilation should be balanced between intake and exhaust, and evenly spread across the attic. I often find air gaps between fiberglass batts and ceiling joists, for example. If batts are used for insulation, I often see that the paper facing is on top, which is an incorrect installation method in colder climates and can also lead to condensation related problems. Blown-in insulation will provide better, more even coverage.
Another common issue is old homes without any ventilation at all or just a few box vents. Because these homes were originally quite drafty, ventilation was rarely needed. But homeowners are now replacing single pane windows with energy efficient ones, adding insulation in walls and in the attic, and making the home much more air tight. If this is all done without adding attic ventilation, it is likely to cause a problem. It is important for a roofer to address the venting when they replace the roof or add ventilation if issues are already visible.
When looking at a home holistically, even the crawlspace ventilation can contribute to premature roof failure.
In the Pacific Northwest, many homes have crawlspaces and a lot of them have crawlspace moisture problems. I often hear arguments that some standing water under the house is normal for our area. Personally, I think if there is standing water, it needs to be addressed. Homeowners can almost always mitigate this with the installation of adequate crawlspace ventilation, French drains, and, if necessary, a sump pump. Keep in mind that the moisture from under the house can go through wall cavities all the way into the attic, leading to high moisture levels and potentially shortening the life of the roof.
Here are some examples of other ventilation and insulation issues that may lead to moisture:
A roof is only as good as its installation. Unfortunately, some companies cut corners and the homeowners often can’t tell there’s a problem in the beginning.
Multiple layers of roof shingles (or even asphalt shingles on top of wood shingles) can cause the roof to look uneven. Any extra layers add additional weight to the roof, thereby shortening its life expectancy. While it may save money in the short term, it will add to the cost the next time the roof needs replacement.
Multiple layers of roof shingles also make it difficult to inspect the sheathing for leaks and signs of deterioration. Water can travel between layers and the leak may be visible in a very different location from where it actually is. Additionally, in roofs with added layers, I often see that the nails used to fasten the shingles are too short and are barely visible in the attic. If that is the case, they can slowly work their way out and high winds can lift the shingles and break them. These issues typically void the manufacturer’s warranty.
A good company will pay attention to detail when it comes to installing underlayment and flashing. Proper installation protects the fascia board and keeps water out.
In reality, drip edge flashing is often too short and doesn’t overlap into the gutters. Wind-driven rain can get pushed back, eventually rotting out the fascia board. The underlayment should be on top of the drip edge flashing and below the rake flashing.
Sometimes, roofers don’t install underlayment near the drip edge and start it higher up. I try to lift the shingles and check for the correct installation by shining my flashlight underneath. If the drip edge flashing is also missing, the sheathing is often already rotting along the edge.
Furthermore, the builders should install the shingles in a staggered way to prevent leaking. Seams should never align at each row. Different manufacturers have different requirements. But the offset is typically between five to eight inches”. (See installation example below.)
Adequate kickout flashing is often missing on older roofs, too. But even on newer roofs, it’s often too short. It should be four inches high and four inches wide. Otherwise, water can easily overshoot, defeating the purpose of the flashing, which is to divert water away from the wall cladding and into the gutter.
Without kickout flashing, I can often see damage along the siding directly below. The damage can be worse if an improperly flashed window is located directly below this area. With leaks frequently emerging around chimneys and skylights, inspectors should check the step flashing and counterflashing here, as well.
Any roof needs maintenance. Regularly cleaning the gutters is also very important to protect the drip edge from water damage. Otherwise, leaves and needles can accumulate, allowing moisture to be soaked up and potentially seep under the shingles.
In our moist climate, we commonly find moss on roofs that are just a few years old. Moss has very strong roots that can cause a lot of roof damage. It can grow under the shingles, lifting them up and creating a pathway for water.
Homeowners should perform regular moss treatments. (Not power washing. It’s too powerful and not only removes the moss, but also the granulate, taking years off the life of the roof.) They should also maintain the caulking on exposed nails, such as the ridge shingles and vent flashing, to prevent water intrusion.
Lastly, manufacturer defects can lead to premature roof failure, too.
For example, CertainTeed Horizon organic shingles that were manufactured between July 1, 1987 through 2005 have been subject to a class action lawsuit.
It can be difficult for a home inspector to determine the brand and type of shingle once the roof is installed. Sometimes, packaging can be found that identifies the shingles. When in doubt, I recommend an evaluation by a licensed roofer.
Home inspectors aren’t home builders, roofers, or shingle manufacturers. And yet we play an important role in helping clients get the longest life out of their roofs. A thorough inspection can identify existing issues, allowing clients to address them proactively and prevent costly repairs later. By educating yourself on proper insulation and venting techniques, proper roof installation, roof maintenance best practices, and current manufacturing defects, you can provide your clients with a better service.
We hope you enjoyed Uli Sommers’ roof inspection guide on premature roof failure. Understanding common home inspection roof problems can make you a better inspector. Whether you’re accused of missing a roof leak or roof flashing problems, our insurance helps you avoid claims against your home inspection business. Learn what errors and omissions insurance is and why it’s important for protecting your business.
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