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The 5% Rule Of Missing Insulation

Many insulation studies have come to the rule of thumb consideration that can be called

The 5% Rule of Missing Insulation.

Basically stated, if a given area, say a wall or ceiling in a room in a home, is missing 5% of insulation, that missing 5% will cause a more than 50% loss in R-value for that area.  To repeat: 

More than 50% loss in R-value for that area.

That is substantial!

Let's say you are in newer construction, and there because the homeowners have called about cold rooms.  If Mighty Mo is tagging along doing a thermal image sweep of the house to check on the insulation, and the high wall in a cathedral ceiling room is found to have missing insulation, would the room feel cooler?

The answer is YES!

This is no mystery.  This is not rocket science.  Enough missing insulation, let's say 5% or more of a given area, results in a very uncomfortable room. 

Turning on the heat in winter, and letting it influence a room, and then viewing a wall that has a uniform line where it is obvious the insulation seems to end, a thermal camera can tell a lot!

That line on the wall is 9' high.  It appears to me the rolls of insulation used in that wall were 9' long.

Perhaps the installers did not have a tall enough ladder that day to insulate higher and were going to get back to this wall after lunch?  The insulation at the edge of the ceiling isn't so great either.

I think what we are looking at is the attic cavity of the townhouse next door, above a room in that house that does not have a cathedral ceiling.  The insulation high on the wall in this subject house looks to be missing altogether.  Since it is a shared wall it is not as cold as it would be if this was the exterior wall of the room.  You can see that the cooler temperature is toward the edge of the roof, closer to the outdoors.

My recommendation:  thermal cameras not only reveal information, they are very instructive in that they define it.  The problem in this room is immediately evident.  This is definitive information!  It is derived without any invasion to the wall at all.  This area could not be seen from the attic space of the house next door because the area seen here is between the interior wall of this room and the fire wall between the two houses.  A thermal camera is the only way to clearly define this problem.

 

 

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 11 commentsJay Markanich • January 20 2016 01:48AM

Comments

 Good Wednesday morning Jay Markanich . Once the sheet rock goes up, a lot of sins are covered as well.

Posted by TeamCHI - Complete Home Inspections, Inc., Home Inspectons - Nashville, TN area - 615.661.029 (Complete Home Inspections, Inc.) almost 3 years ago

The so called Multiplicity of Sins, Michael!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

Wow, that's an interior wall?  It looks like windows.

Posted by Women of Westchester Working Together, Women helping Women get ahead (Women of Westchester Working Together) almost 3 years ago

It almost does Debbie.  It abuts the neighbor's townhouse.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

This is why blown in insulation is the best, it fill all nooks and crannies. Different types of blown in insulation are fiberglass, cellulose and foam.

Posted by David Popoff, Realtor®,SRS, Green ~ Fairfield County, Ct (DMK Real Estate ) almost 3 years ago

I agree David, but seldom see cellulose inside walls.  But here even the bats are missing!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

It only takes one boo boo to eliminate the good work they did.... if there is any!

http://activerain.com/blogsview/4810123/is-your-attic-access-door-insulated-

 

Posted by Fred Hernden, CMI, Albuquerque area Master Inspector (Superior Home Inspections - Greater Albuquerque Area) almost 3 years ago

Mighty Mo to the rescue again.  I'd hate to see what you would find in my house.  My next major project is to install additional insulation in the attic.  Do you have a professional opinion on cellulose vs. fiberglass?  Cost vs. effectiveness?

Posted by Stephen Weakley (Nationwide Mortgage Services) almost 3 years ago

This is in that same room Fred!

They wired up the ceiling fan and did not replace the insulation.  The roof is in the sun, so the attic isn't that cold.  But some cold is reflected here.  And this is a cold room!

Stephen - cellulose has superior R-value per inch (3.7) than fiberglass (2.2 for loose fill) but the insulation guys usually say not to blow it over fiberglass because it weighs the insulation down.  However, adding R-19 to your attic only adds 1/3 pound per square foot!  So it is not heavy.  Buy it when it's on sale, and make sure they blow in the number of bags you bought, and buy enough bags to create the number of extra inches you desire.

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) almost 3 years ago

Jay, this was a very interesting article - thank you. Sad that a contractor's cutting of the corners could have such consequences to the homeowner and to the environment.

Posted by Lisa Friedman, 29 Years of Real Estate Experience! (Great American Dream Realty) almost 2 years ago

It has huge consequences Lisa, and every study done now, by bona fide agencies like the Oak Ridge Labs, agree.

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

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