What I'm Seeing Now


How High Winds Damage Roofs

How high winds damage roofs.

This blog is taken from a letter to an insurance company defending a client who had severe roof damage from a tornado, with ongoing subsequent leaks.  The insurance company took the position that the wind damage was "wear and tear," that the leaking was "coincidental to and not because of the tornado," and denied her claim.  This homeowner contacted her home inspector!

Any roof can leak at any time depending on the direction and force of rain.  That is an axiom that you can take to the bank. 

In April 2017 we experienced a tornado that caused severe damage to our roof shingles.

This is a photo of one aspect of my roof.  You can see a section of shingles on the lower left and lower right which were removed.  Other shingles were shredded.

Leaking happened immediately from two skylights and at the lower right in this photo where the roof meets the corner of the siding.  These thermal images above are from inside my house just under that siding corner.

The leaking continued until the roof was replaced.  A black and white image is the best way to demonstrate leaking, but clients (and insurance companies) want sexier images, so a color palette was chosen to best describe the leaking locations.

When wind hits a roof its effect is not uniform over the entirety of the surface.  Some spots will experience higher and other spots lower wind pressures.  For that reason damage can be more or less severe.

The direction and force of rain can change during the course of a tornado, which usually doesn't affect a house for a very long period of time.

Windward and leeward, some areas of the roof can experience positive pressures at the same time that others are experiencing negative pressures.  The photo above is on the windward side of the tornado's approach - meaning the direction from which the wind was blowing.

Positive pressures lift shingles through pushing; negative pressures lift shingles through suction.

That is why on the windward side photo above the shingles are both shredded through pushing and removed through suction.  The same kind of damage happened on the leeward side of my house.

Leaks happen because of material movement.  Where shingles move even a little the wind will get under it and drive water to those spots.  And leaking can happen even where tar paper is still present.

Damage starts as a small spot, and then with continued rains the damage worsens and leaks become more and more pronounced.  Leaking is not "coincidental" to a tornado, or wind damage.  It is "incidental."  Coincidental means there is no causal relationship, things just happen.  Incidental is best defined as something that happens as a consequence of something else.  On both my roof, and my client's roof, the damage and leaking were incidental.  So when an insurance company takes the position that leaking after a tornado is "coincidental," that position cannot hold up to the science of tornadic roof damage and leaking.

My recommendation:  a roof is a fickle place.  It can and will react to all kinds of weather.  Newer shingles, the architectural shingles that look like a textured layer of roofing, are designed to handle winds as high as 140 mph.  They are thicker and more solid, and have better glues to stick them together.  Some newer shingles are called "forever shingles."  While they aren't really able to last forever, they will probably last a long time, even 30 - 35 years.

Note:  following my letter to the insurance company my client's roof claim was approved.  She was elated and her home inspector gets a Gold Star.  Aw, shucks.



Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560


Comment balloon 14 commentsJay Markanich • December 14 2017 11:25AM


  When we built our house...David made the little decisions...like what KIND of shingles we had...I made the BIG ones...what color they were.....and the thickest that were made at the time with nary a wrinkle anywhere 21 years later.

Posted by Sally K. & David L. Hanson, WI Real Estate Agents - Luxury - Divorce (EXP Realty 414-525-0563) over 2 years ago

Good morning, Jay Markanich whenever I replaced a roof on a home I knew I would keep, it was a 40 year architectural shingle... so far, so good!

Posted by Barbara Todaro, Marketing Agent for The Todaro Team (RE/MAX Executive Realty ) over 2 years ago

A definite gold star goes to that home owner's inspector! Thanks for sharing.

Posted by Kat Palmiotti, The House Kat (406-270-3667, kat@thehousekat.com, Broker, Blackstone Realty Group - brokered by eXp Realty) over 2 years ago

Good morning Jay. Sometimes it takes a little expertise to get the correct decision. Enjoy your day!

Posted by Wayne Martin, Real Estate Broker - Retired (Wayne M Martin) over 2 years ago

Good morning Jay. Well this scared me for sure. I had high winds and roof damming and it was very costly to fix.

Posted by Sheila Anderson, The Real Estate Whisperer Who Listens 732-715-1133 (Referral Group Incorporated) over 2 years ago

We always joke about tornado straps on roofs in Oklahoma because a tornado won't care, but resistance to high winds is more what it is about.

Posted by Joe Pryor, REALTOR® - Oklahoma Investment Properties (The Virtual Real Estate Team) over 2 years ago

That must have been a wild ride!  I've seen the damage they can do, but never actually rode one out.

Posted by Stephen Weakley (Nationwide Mortgage Services) over 2 years ago

Your knowledge and abilty to make your point took care of your client.  I am impressed and so glad she called you.

Posted by 1~Judi Barrett, BS Ed, Integrity Real Estate Services -IDABEL OK (Integrity Real Estate Services 118 SE AVE N, Idabel, OK 74745) over 2 years ago

S&D - a little research on roof shingles and types goes a long way!

Barbara - per square (how roofs are measured for size and materials) the architectural shingles don't cost that much more.  And they require longer nails which aren't that much more expensive.

Thanks Kat.  I did her inspection 3 years ago and she still thought to call me.

Wayne - I think that after reading my letter the insurance thought that if she pursued this they would lose.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Sheila - roofs can be expensive!  And it pays to hire a good roofer, for sure.  See my post on the roofing company that didn't understand OSHA a couple of months ago.

Joe - if your house was built after 2000 it already has them!  See the straps to the right.

Stephen - my daughter called me during the tornado saying that the house across the street had shingles blowing all over the place.  I told her to go to the basement.  That was the roof I featured in my post on the roofers who knew nothing about OSHA.  The roofing job was terrible.

Judi - thank you!  I tell my clients to call me any time they have a question or problem and I will help.  I actually did her inspection 3 years ago, and she still remembered that.  She really was ecstatic.


Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Wear and tear? Holy crap! I see alot of that here, I'm sure you see lots of cracked shingle tabs from freeze thaw cycles, and then the wind just blows them off!

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) over 2 years ago

Yes, Fred, wear and tear will break shingles, but tornado damage is not wear and tear!  The letter the insurance wrote my client was unbelievable.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago

Thank you very much, Jay, for sharing your experience and your advice.

Posted by Roy Kelley (Realty Group Referrals) almost 2 years ago

Thanks, Roy.  I do it often!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 2 years ago

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