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The Critical Eye!

Michael Leavitt’s professional inspection related blog.

Weird Roof Snow Melt = Poor Insulation???

Weird Roof Snow Melt = Poor Insulation???


ML2014It is bitter cold here in Northern Utah and this 2015-16 snow season is much greater than recent years. The snow, combined with the below freezing temperatures makes it rather easy to tell which homes have good insulation and which homes are severely lacking. This blog entry will give homeowners a way to self-diagnose attic insulation issues.

NOTE: If you live in snow country, then you will love the following information. However, if you are my warm weather friends catching waves in 60 degree weather in Southern California, then you will find it amusing at best.



Attic insulation is designed to help keep the temperature inside the home constant. We spend lots of money each winter cranking our furnaces and building fires in our fireplaces in an attempt to keep the interior warmer than the cold exterior temperatures. The second law of thermodynamics states that heat flows from an object at a higher temperature to an object at a lower temperature. If the interior of the home is 68 degrees and the exterior of the home is 18 degrees, then what direction does the heat want to flow? The laws of physics dictate that the heat will want to go upwards and outwards, but our attic insulation helps to create a buffer zone and keep the heat inside the home's interior.


Yes! Warm air in the attic causes the snow on the roof to melt in weird patterns and this can lead to ice damming, water entry, mold, and rot.


Colder - Most homeowners give very little thought to the attic temperature. You would think that if the attic air is warmer, then the cold from the outside would have a harder time getting inside. This would also keep the deep snow off the roof. This seems logical until you stop and ask yourself, "Self, if the attic is warmer, then where did the heat come from to warm it up?" If the attic is warmer than the exterior air, then heat is escaping from the home's interior and into the attic. Guess who is paying for that heat loss? Yep, it is the one who pays for the utility bill.


We go to great lengths to ventilate our attics.  Most homes have intake ventilation along the lower soffits and then exhaust vents at the gables and/or on the roof or ridge. This ventilation is designed to get outside air flowing through the attic so that the attic air is similar to the exterior air temperature. If the venting is poor, then the winter attic will be warmer and the roof snow will melt prematurely, and cause frost build-up on the interior side of the attic. Good ventilation is a top priority.


Absolutely! - The more insulation in the attic, the bigger the buffer between the interior and attic air spaces. In the early 1900's you were lucky to have 1" of insulation in the attic. By the 1960's 4" to 6" was more common. By the time Jimmy Carter became President in the late 1970's the focus on energy efficiency really started becoming a priority. President Carter's influence caused insulation depths jumped from R-19 up to a very deep R-32 in the colder parts of our country. And here we are today with R-38 is the norm and many homes in our area having R-50. The R numbers are a rating system that translates into varied depths depending on the type of insulation. For example, blown-in fiberglass insulation takes 12 to 15" to achieve R-38, whereas blown-in cellulose insulation only requires 10-12" of insulation to achieve the same R-38 rating.


Voids in the insulation - It would be great if the blanket of insulation was perfect and even across the entire space, but this isn't a reality. We have flues, ducts, plumbing vent pipes, vaulted ceilings, chases, and just plain missed areas that were too difficult for the insulation installers to reach. I have been in thousands of attics in my 20 plus years inspecting homes and it is amazing how many issues in the attic ruin the insulation blanket. And then there are the damages caused by people accessing the attic and trodding through the insulation that leaves a pathway for heat loss. The majority of insulation issues are easily resolved, and yet most go unidentified and/or unresolved. The result is higher utility bills.


You can pay for a thermal imaging audit, or for free you can walk outside right now and look at your roof. I say right now because as I type this it is 18 degrees and snowing. There are certain times of winter where it is very easy to tell if you have excessive energy heat loss through your attic. Like I said, walk outside and look at your home from all four sides. If heat is being lost, it will show up in the way the snow looks on your roof.


Here are 10 good guidelines...

1) NORTH SIDE - The north side of the roof is the best revealer of issues because it receives the least amount of direct sun.

2) COMPARE HOMES - Are your neighbor's homes of similar vintage? If so, then all should look pretty similar. If no snow is on your roof and your neighbor's have 8", then you probably have issues. Look at the two homes below. They are neighbors... Do you see anything wrong with the right side of the home on the right?


3) TREES - Mature trees can also block snow fall and make it look like part of your home is poorly insulated, when in fact those areas never received deep snow in the first place.

4) SWAMP COOLERS - If you have large amounts of melt around the swamp cooler, then you probably did not add sufficient pillows inside the duct on the ceiling and the heat from your home is flowing right up and out the unit.

5) DEEPER INSULATION ON PERIMETER - Look at the insulation depth.  Older poorly insulated homes often show up with deep insulation around the perimeter while the snow is much thinner over the interior. This is classic for homes built with 6" of insulation or less and never have had an insulation upgrade.



6) WEIRD SNOW MELT PATTERNS - Look at this photo below and you will see very strange melt patterns. You can see the large rectagular melt lines as though there may be a vault in the living room ceiling. Look closely at the melt line about 2' up from the lower edge. This is from an insulation void that will then cause premature melt and an ice dam behind it when the snow refreezes. Inside the home there will surely be water entry evidences, which lead to both rot and mold issues. Look how puffy and thick the rest of the roof looks t the right of the image. This indicates good insulation.


7) SMALL AREA VOIDS - If there is just a small area, then you may have just a small void that will require further investigation inside the attic. The attic below has several small voids as well as an old swamp cooler duct in the attic. All of these areas are correctible and big energy losers for the owner.


8) VISIBLE RAFTER/TRUSS LINES - In many cases you can see the spacing of the rafters/trusses. This indicates uneven temperatures along the roof line and the ghosting pattern of the framing underneath the sheathing becomes visible.  Rising heat in the attic comes up through the plywood easier than where the trusses/rafters are located.



9) ICICLES - Look at the icicles coming off your roof. Are they similar to your neighbor's? Or are yours more prominent? Or are they only in one ore two locations. The icicles can be their own indicator of issues, but sometimes it is from a poor insulation.


10) ATTIC FURNACE - You might be one of the 5% of Northern Utah homes with a furnace installed in the attic. This can play havoc with roof snow melt and be the source of ice damming and water entry. There are solutions where the area around the furnace can have an insulation barrier installed that separates the furnace area from the rest of the attic space. Whether or not it is an issue is best left to the professionals to determine, but just realize that attic mounted furnaces can be the source of odd water entry and mold issues.

PHOTO BELOW - The only explanation is poorly insulated areas of the attic. This is a north side view, but it clearly shows that there are insulation issues on the left side of the home. Having never been inside this particular attic my guess would be that there is an attic mounted furnace or an opening from the water heater and furnace room directly to the attic above (see the flue).


Dirty-HarrySo there you have it, a basic guide to self-diagnosing your attic insulation woes. The snow melt patterns tell you where to investigate further... Now dealing with the identified areas is a whole other issue. As Clint Eastwood said, "A man has got to know his limitations!" When in doubt, call in the professionals.

Stay warm! Michael Leavitt * Master Inspector * * Orem, Utah


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