How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

What things can void a shingle roof warranty?

Saturday, March 5, 2022

Anything that shortens the life of the shingle or makes roof leaks more likely is excluded by a shingle manufacturer’s warranty. Here’s our list of 14 of them. It varies somewhat according to manufacturer, and warranty terms often change from year-to-year, but these are the most common issues that can cancel or reduce your warranty.

•• New roof over old roof - Applying a new shingle roof over an existing one not only voids the warranty, it also reduces the life expectancy and causes other problems. This exclusion may not be stated directly in the warranty, but an old roof is not an “approved deck” for application of the manufacturere’s shingles. See Are two layers of shingles better than one? for more on this.

•• Improper installation - All manufacturers have installation instructions that must be followed exactly. Nails that are overdriven, underdriven, or not perpendicular to the roof deck are one problem. Improper storage before installation is another example.

•• Low roof slope - A roof slope between 2/12 (rising 2” vertically for every 12” horizontally) and 4/12 must have a manufacturer-approved underlayment, and under 2/12 is not acceptable. More info at What is the minimum pitch/slope of an asphalt shingle roof?

•• Roof penetrations after installation - This includes antennas, satellite dishes, skylights, and light tubes. 

•• Poor attic ventilation - Soffit vents obstructed by insulation covering them, and missing ridge or roof vents, are examples.

•• Polyurethane spray foam under roof deck - This is sometimes called a “hot roof” because it does not allow heat to dissipate under the roof deck into a ventilated attic. Details at Why is spray foam used for attic insulation? •• Pressure washing roof - The water pressure blows off some shingle granules right away, and loosens others that fall off later. Those tiny rock bits on the surface protect the shingle from premature deterioration by the sun’s UV-rays. See Why is granule loss a problem for an asphalt shingle roof?

•• Change of ownership - Most companies allow one change of ownership, within the first few years only. Also, the new owner must register, with documentation of original roof installation and change of ownership, to get the warranty transferred. There may be a reduction in the terms of the warranty for new owner. Since many homeowners replace their old roof just before listing the house for sale, it’s important for the new owner to get all the information on a new roof from the sellers before they depart.

•• Roof warranty not registered - Some companies require registration within a certain time period for the warranty to be valid, but others do not. This is usually done for you by the roofer.

•• Cool weather installation - Shingles require several days of direct sunlight and warm weather for their adhesive seal strips to activate. If that doesn’t happen shortly after installation, the shingles sometimes never seal. Also, any wind damage before the shingles seal is not covered. Go to Do asphalt shingles need time to settle and adhere? for details.

•• Not using approved accessories - A roof is considered an “assembly” of components that includes decking, underlayment, flashings, and other accessories. All of them must be produced or approved by the manufacturer for the warranty to be valid.

•• Painting the roof - Yes, this also voids the warranty. But it is usually done to extend the life of an old roof that is already out of warranty.

•• Damage from ice dams

•• Excessive traffic on roof - Loosens the shingle granule coverage prematurely. So, only walk on your roof briefly and when necessary, and ask any workers on the roof to do the same. 

    Also not covered are: settlement of the structure, objects such as tree limbs falling on the roof, wind damage beyond rated wind speed, and damage due to tree debris or sap. All of this presumes you have the basic warranty. An enhaced warranty provides additional coverage. There are often two levels of coverage: the first few years and later on. And more fine-print details, but let's stop here. 

    Because shingle warranties focus on anything that will cause their product to age prematurely, the problems covered in our article What causes a shingle roof to deteriorate faster and fail prematurely? correlate with many of their warranty exclusions. 

• • • • • • • • • • • • • • • • • • • • • • • • • • • •  

  To learn more about roofs and attics, see these other blog posts:

Why is my roof sheathing sagging between the trusses?

What are the mistakes to avoid when doing attic improvements?

What causes roof shingles to curl up at corners?  

What can I do to prevent roof leaks?

Why is my roof leaking?

What causes shingles to buckle along a line on the roof? 

What causes leaks at a fake roof dormer? 

What causes bubble-like blisters in a built-up and gravel roof?  

What is "ponding" on a flat roof?

How can I inspect my roof for hurricane damage?

How can I tell if a roof has more than one layer of shingles? 

What are the common problems with attic insulation? 

What's the average lifespan of a roof?

Why is it a mistake to replace a roof and not replace its flashings? 

Why is there no attic access hatch in the house?

What is the building code requirement for an attic access hatch, scuttle, or door? 


Are roof trusses better than roof rafters (stick framing)? 

Why is a popped nail in a shingle roof a problem? How do I fix it?

What are the most common problems with wood roof trusses?

What causes a lump or dip in the roof? 

If my roof is not leaking, why does it need to be replaced?

How can I be sure my roofing contractor got a permit? 

What are the dark lines running parallel to shingles on my roof?

Can metal roofing be used on a low slope/pitch roof? 

What are the warning signs of a dangerous attic pull-down ladder?

How can I find out the age of a roof? 

Should I buy a house that needs a new roof?

Should I buy a house with an old roof? 

What are those metal boxes on the roof?

What does "lack of tab adhesion" in an asphalt shingle roof mean?

Why do roof edges start leaking? 

Should I put gutters on the house? 

How much of a roof truss can I cut out to make a storage platform in the attic? 

What's the difference between an "architectural" and a regular shingle roof? 

What does a home inspector look for when examining a roof? 

Do stains on the ceiling mean the roof is leaking?

How can I tell if the house needs a new roof?  

What are the hazards to avoid when going into an attic? 

     Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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