Mastering Roof Inspections: Asphalt Composition Shingles, Part 9

by Kenton Shepard and Nick Gromicko, CMI®



The purpose of the series “Mastering Roof Inspections” is to teach home inspectors, as well as insurance and roofing professionals, how to recognize proper and improper conditions while inspecting steep-slope, residential roofs. This series covers roof framing, roofing materials, the attic, and the conditions that affect the roofing materials and components, including wind and hail. 



A warranty for shingles is a marketing tool, since the warranty seldom reflects the shingle's actual lifespan. A warranty offers a way to roughly compare the expected service life of different asphalt shingles.

As a home inspector, it’s not your job to explain warranties to your client, but you can give them general information that may help protect them, and perhaps answer some questions. That’s providing good service, and good service is something clients appreciate.

Shingles may have one warranty, two warranties, or no warranty at all.

A warranty may transfer once with the sale of the home, or it may transfer as a limited warranty, or it may transfer fully.

Here’s how it works.

Manufacturer’s Warranty

The manufacturer’s warranty is limited to shingle defects that are caused by the manufacturing process. It covers defects that cause shingles to fail before the term of the warranty has expired. This is called “premature failure.”

Manufacturers' warranties are not negotiable, so a homeowner can’t negotiate with a contractor or salesperson for a better manufacturer’s warranty.

Shingles may be warranted for 20, 30, 40 or 50 years, although the 50-year warranty may also be called a “lifetime” warranty.

When a home is sold, the manufacturer’s warranty may not transfer to the new owner at all, or it may transfer one time, or it may transfer with limited coverage, or it may transfer fully. It all depends on how the warranty was written.

Warranty Prorating

Warranties, especially longer ones, often prorate to zero at the end of the warranty period. This would mean that, if, in the 30th year of its life, a roof with shingles warranted for 40 years failed, the warranty may cover only 25% of the roof's total replacement cost, since the shingles were already 75% of the way through their warranty period.  Even less than that time period might be covered, if that’s how the warranty was written. A “lifetime” warranty does not mean that the roof will be covered for replacement cost as long as the homeowner lives in or owns the home.

Installation Requirements

Some manufacturers' warranties cover installation errors, but they require installation by manufacturer-certified installers using the manufacturers' products exclusively, from the underlayment on up.

Labor and Disposal Costs

Manufacturers' warranties may cover only the cost of new shingles, or a portion of their costs, but not the cost of labor for installation, especially further along in the warranty period. Labor costs for installation are affected by the roof pitch. There’s typically an extra charge for steeper pitches, which may not be included in the original warranty.

Roof replacement may require removal and disposal of the existing shingles, and that may not be covered, either.

Wind Warranty:  Separate and Shorter

The wind warranty is almost always a separate section within the overall manufacturer's warranty, and the time period covered is generally shorter than that of the overall warranty.

The average wind warranty for 20- to 40-year shingles is five years.  For 50-year shingles, it’s 10 years. This is because shingles become less wind-resistant as they age.

Adhesive Strips:  Failed Bond

Some wind warranties may not cover shingle blow-off before the adhesive strips fully bond to the shingles. This means that shingles installed during colder weather may be at risk, since the adhesive strips rely on heat to develop an adequate bond.

In some climates, shingles installed during the cold season may take months to bond completely.

Installation Deficiencies

Many wind warranties become void the day they’re installed because of installation deficiencies.

These kinds of deficiencies might include lack of underlayment, improper fastening methods, or installation over a non-compliant substrate, such as an existing layer of shingles.

Manufacturers' Warranties Vary

Put simply, the terms of manufacturers' warranties can vary widely. If the seller claims that a warranty is a selling point, you might want to suggest to your home-buyer client to review the warranty terms carefully.

Here, you see warranty information on the shingle package.

Contractor’s Warranty

The second type of warranty available is the contractor’s warranty. It covers proper installation methods and workmanship. The terms of a contractor’s warranty may be negotiable, so they also vary. Jurisdictional requirements may influence the terms.  Jurisdictional requirements include those instituted by a city, county, state or provincial government.

Some contractors offer an extended warranty as a marketing tool. Homeowners tend to believe that this shows confidence on the part of the contractor in the ability of the installers. More often, it’s because the contractor knows that any problems due to improper installation are likely to appear during the first five years after installation, when the home would still be covered by a standard contractor’s warranty anyway.

Although manufacturers' and contractors' warranties are technically separate, improper installation or damage caused by workers may shorten the service life of a roof, in which case the manufacturer would deny the claim and refer the homeowner to the contractor.

There is no single cause of shingle failure. The forces that have the greatest effect on shingles are different in different climate zones, and will be further influenced by many other conditions.  If a leak occurs within the first few years of roofing installation, the leak is probably installation-related. If a new roof lasts for a few years but fails prematurely, the cause is usually manufacturing-related, although an older roof may also fail prematurely because of poor design or maintenance.  The real cause of failure is not always obvious and may involve a combination of factors.

You might recommend that the buyer ask about any roof warranties that transfer with the sale of the home. If the roof is not covered by a warranty, the buyer may want to purchase an insurance policy that will pay for roof damage. Your comments about warranties can help make clients aware that they may need additional protection.


Learn how to master a roof inspection from beginning to end by reading the entire InterNACHI series: Mastering Roof Inspections.

 Take InterNACHI’s free, online 
Roofing Inspection Course
Mastering Roof Inspections
Roofing Underlayment Types
Inspecting Underlayment on Roofs
Fall-Arrest Systems
Roofing (consumer-targeted)
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