What I'm Seeing Now

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Anatomy Of An Ice Dam

 

 

When deep snows happen, ice dams often happen too. 

Notice two words in the left diagram:

Convection and Conduction.

An easy way to remember what they do is this:

Conduction is THROUGH and convection is TO. 

Cooking heat is conducted through a frying pan into the food, which heat also convects to the upper level and the upstairs feels warmer.

Deep snow on a roof creates a condition ripe for ice dams.  There are a lot of battles going on between heat and cold.

Since Friday I have gotten lots of calls because of ice damming.  And it is a huge problem.  And some of the icicles I have seen are enormous!  They could skewer a woolly mammoth!

 

 

 

 

 

This photo shows literally what the diagram is teaching above.

This is a box window on a house I visited on Saturday.  To the right is the garage and the left a box window.  The other side of the box window looks just like this side.

Trapped water is being forced through the siding, soaking into the garage wall and onto the garage floor.

Trapped water is also being forced up into and under the cedar shakes and into the box window ceiling and framing.

This is what my thermal camera saw in that box window:

 

This is immediately under those shakes you see in the photo to the right.

The pattern of water intrusion is clearly visible as lavenders and purples.

The darkest purple is 38 degrees F.

 

The other side of this same box window, about 6' wide, is here:

 

This moisture is clearly getting into the wood framing of the window as well.

Ice damming is a real problem and happens around here every time we get deep snows.  Fortunately the snow is melting slowly and saving foundations.  Too much water pressure around the house and, well, other problems begin there too!

My recommendation:  Pay attention to your house!  If possible, try to eliminate some of the build up at the bottom of the roof.  Your house will appreciate it. 

I bet your gutters will too!

 

 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

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

www.jaymarinspect.com


Comment balloon 16 commentsJay Markanich • February 15 2010 01:57PM

Comments

Jay,

Great write up!  Great definition of the causes of ice damming and leaks.

Even better?  Living in North Carolina and not dealing with that much snow and ice.

Posted by Mike Jaquish, 919-880-2769 Cary, NC, Real Estate (Realty Arts) over 9 years ago

Wow ! Such an informative post. The graphics speak for themselves. Timely and of use for many.

Posted by Claude Cross, Charlotte NC Homes For Sale (Homes By Cross, Inc. ) over 9 years ago

This is a real problem, thanks for the post.  We experienced this around 7 years ago, the last time we got a big blizzard.  This time we proactively shut the 2nd floor zone off since that was the cause of the melting the first time.  So far, so good!  Thanks!

Posted by Craig Richardson (National Realty) over 9 years ago

Mike - no snow?  Wow, are you missing out...

Not!

Claude - thank you!  Did you see my previous blog post on ice damming?

Craig - it is a problem and you were smart to turn off the heat.  Some heat will still CONDUCT throught the insulation, but certainly not as much!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 9 years ago

Well, I'm inspired to go out and look at my roof tomorrow in the daylight.

HA!  Who am I kidding??  I still have 3 feet of snow in the yard. 

How do I know if I have ice dams??? 

Is water going to intrude somewhere???? 

GEEZ!!

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley, Homefinders.com, MD & VA Homes and Real Estate) over 9 years ago

Well, Lenn, you will probably know when it does intrude!  It may have melted enough by now that you won't have any.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 9 years ago

Jay,

I have this one area on my house where, every ten years, I get an ice damn. When it is re-roofed something is going to change there. As you say, Lenn will know.

Posted by Steven L. Smith, Bellingham WA Home Inspector (King of the House Home Inspection, Inc.) over 9 years ago

Maybe you can build up that spot with a little Scotch tape or even duct tape Steve.  Likely the roofers didn't do it right the first time.

There are some really good rubber membranes out there, used in northern climes, which seal up spots real well under shingles.  And, under shingles or shakes, that membrane lasts a long time.  If the sun gets to it, it will deteriorate rapidly.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 9 years ago

Jay - the infrared pictures really drive home the point. Priceless!

Posted by Eric Middleton, Professional Property Inspector (Closer Look Property Inspections Inc.) over 9 years ago

Definitive they are!  Thanks Eric.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 9 years ago

Jay - we've been having the same issues around here.  I use Google analytics for me web site, and 7 of the top 10 search terms that customers have used to find my web site in the last month contained 'ice dam'.   There are a lot of people looking for solutions!

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 9 years ago

That's the third beautiful icicle picture I've seen at ActiveRain in the past couple of hours. It must be icicle night!

Posted by Not a real person over 9 years ago

Glad we don't have that problem in Las Cruces, NM

Posted by Ron Chorey, Ron (Remax Classic Realty) about 9 years ago

Reuben - that little problem made me a lot of money.  But it was a hard couple of weeks!

Russel - this was a while ago, but I know people around the country face this often.  It was a hard time for many people around here.

Ron - no ice dams?  What fun is The Crosses then?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 9 years ago

Wow, what a great description and write up of something I will never personally experience.  We just don't have that kind of weather in the coastal areas of San Diego.  Shucks!

Posted by Robert T. Boyer, San Diego Real Estate & Mortgage Loans, Ph.D. | VA Home Loan (FHA Loan, VA Loan, Jumbo Loan,FHA Loans,VA Loans,Jumbo Loans) over 8 years ago

Well, Robert, I bet you studied stuff in college, anatomy and such, that you haven't had use for since too!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 8 years ago

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