Ice dams and heatloss
Seacoast Inspections
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Ice Dams
Your house is speaking to you. Are you listening!

         Are you one of those people who has installed heating cables on your roof or had sheets of metal installed in the first two feet to "take care of your dam ice problem". Excuse me, I mean "ice dam problem". I'm sure you have gotten all kinds of good advice from friends, neighbors and even home improvement store employees. Yes, what you need is heating cables they are in isle 6 half way down on the left. You get there, and there they are. The box has a nice picture of how well they perform and they are even on a thermostat so they will "save you money".  I have seen  even well known popular websites suggest as a quick fix to put calcium chloride in panty hose and lay it across the ice dam. How about snow rakes. They sell them by the hundreds at the home improvement stores, they have to fix my ice dam problems. Better yet, a neighbor told me that if I put a heater in the knee wall area and warm up the space enough it will prevent any ice from forming on the bottom edge of the roof.  Any of this sound familiar.
Let's cut to the chase. The problem is heatloss. There are some rare cases where an attic can be perfectly insulated and ventilated and you still develop some ice dams. What I am talking about here are the dams that effect 98% of the homes that have problems. The bottom line is to much heat is making it's way into the attic space or the ventilation system in the roof is inadequate. Most of the homes I inspect it is a combination of the two that creates the problems.
So alittle ice develops on my roof, so what. Ice dams can lead to wood rot, delamination of sheathing, reduced R-value in insulation,  interior water damage to finish and structural  components, development of mold, and other health related conditions. There are a number of people you can possibly blame from the HVAC , GC, Insulation contractor, roofer, electrician, Architect, Plumbers, sheetrockers, and even you. I have seen it all and most of the largest contributors to warm attics come from spots you have no visible way of seeing. That is why thermal imaging is such a great tool for finding all these contributing factors that lead to warm attics. The beauty is the inspector walks around the house with out having to take anything apart and can thermally see these areas.
Look at the picture to the right. There was no access
to this area for visual inspection but thermally you can see
the problem. Insulation has been omitted and heat can
now readily conduct  through the sheetrock into the attic
space behind. Actually I just lied. When I saw this wall I
didn't even need my Infrared camera to diagnose the
insulation was missing. If you look at the wall closely you
can see a slight stain that appears to be in between each
stud bay. What is happening  with out getting scientific
is very fine particulates in the air, plate out on the colder
surfaces and create these stains. Usually these stains are
more pronounced in homes that have oil heat, burn
candles, or have smokers in the house. So if you walk
around your house and stare at the white walls you might
not need an Infrared inspection. Just kidding.  Did you
move your mouse over the picture. Now you will never look at a stain on the wall the same again.
Getting back to the fact your house is speaking to you. Do you ever have condensation on your windows or mold showing up on ceilings or walls. You continue to clean them up and wipe them off but the problems return. Your home is speaking to you telling you something is wrong. Your humidity might be to high or again it might be as simple as insulation is missing or disturbed. Condensation is forming in this area allowing mold to grow. You can clean it, but with out fixing the cause it will come back. The same thing happens with ice dams. You can use one of the many methods to deal with the ice dams after it has developed or you can actually stop what is the root cause of the ice dam to begin with. Ideally you would like the attic space to be the same temperature as outside but that is really unrealistic. Even if it was perfectly ventilated, air sealed, and insulated. Heat from the home is still going to warm that space up alittle. I have heard everything from 0 -15 degrees F is acceptable. Take a look at the diagram below.

This gives you a visual idea of what is taking place on the roof and why the ice dams are occurring.
Every house and building is different and heatloss can be escaping in many different ways into the attic. Below I am going to show you one case study of a typical ice dam with the causes and effects. This doesn't cover all possibilities and is not this simple all the time.

Case study #1 - Call comes in from home owner who has a 3 year old condo that has ice dam issues. He wants me to inspect the home and figure out why .

What is the first thing you notice besides the ice dam on the porch. Yes, the snow melt pattern on the roof. Turns out those lines match up perfectly with the attic space inside.  Here is what the I found inside.

This looks fairly normal doesn't it. There  are no signs of mold on the sheathing or rafters anywhere which is a good sign. Personally I never like to see forced hot air distribution lines in unconditioned spaces. They leak, and think about the insulation on those ducts. We build are houses with R-19 in the walls and R-38 in the ceiling but for some reason we find it acceptable for R 4 - R7 on the HVAC ducts. Doesn't make sense to me. You will naturally be giving up heat  through these ducts.
Before I had entered the attic hatch I had a quick walk around the condo. I noticed the supply and returns for the furnace where in the second floor ceiling. I knew there was only one unit, and I went to the basement to see where the supply and return entered the first floor on there way to the attic. Once I found that area I went back up stairs and shot this area first. This is what I saw.

This is a very large chase from the basement to the attic.
On the left you can see what I'm guessing at this point is
the return and supply for the second floor. On the right you
can see it appears to be cooler.
So off to the attic hatch to see what we can find. The first
thing I notice is the hatch itself is not air sealed and insulated.
This will allow warm air to be drawn in around the hatch and
heat to easily conduct through the hatch. This alone is not
enough to cause our problems but is certainly contributing.

Once in the attic I start to take alook around 
and try not to put my foot through the ceiling.
The first place I want to look is the where the
ducts penetrate the attic floor. When I get over
there this is what I find.

You can see a couple of interesting things. First
the obvious thing is the top of the chase is wide open
to the unconditioned attic. Second, is that chase is in
the middle of the house and all four sides are warmed
by conditioned spaces. Third, there is no insulation on
any of those interior walls. Forth, the metal duct is not
air sealed or insulated below the attic floor. All these
things together add up to a large volume of heatloss
that is occurring 24 hrs a day. This is like a heat pump
stealing heat from the house and HVAC system and 
depositing it into the attic.

Couple other things of note that are contributing to the heatloss into the attic. In my opinion it is not good practice to install recessed lights in cathedral ceilings. There are three basic types of  recessed lights that could be installed, IC (In contact w/insulation) , Non IC,  or air sealed . Even though the air sealed prevents air movement into the roof space heat is still conducted into this space which is often as little as an inch or two clearance below the roof decking.

Below is a IC rated light.

  Above is Non IC Rated and below is Air Sealed

Even in regular second floor ceilings I see alot of IC and NON IC rated lights that are providing air paths and heat from the light itself and the living space below. Depending on the the amounts and use these can be contributing to ice dam situations in peoples homes. The best way to go is use the Air sealed units that have gaskets to prevent air leakage around them. They seal tight to the drywall and you can insulate over them.

Here is an example of the recessed lights in this unit.
You can see this light isn't on and the colder air is coming in
through the fixture. My guess is this is not an air sealed

Now getting back to our attic space. I didn't have access to the gable area that is over the front portion of the garage. If you look back at the first picture you will notice that there is a V shaped melt pattern in that roof. One thing I could see was the supply duct (R-4) squeezed it's way in just under the peak area of this gable.  Now there could be a whole or tear in the insulation, or duct itself at this point.This is a bathroom ceiling and from inside I did take this image that shows heatloss in that general area.

Again this by itself is not our smoking gun but it is
another contributing factor to the conditions that cause the
Ice dams.

Now when I walked out of this bathroom I realized
there has to be a rather large dead space in the eave areas
that has no access. So I shot the walls and one more
piece to the puzzle was discovered. The insulation was either
missing completely or poorly installed to begin with. It is
possible insulation was installed and fell out of the bays.
Regardless this is a large surface area that is transferring
heat by conduction into that space which happens to be
right below the valley. And right below the valley in the worst
of the ice dam.

Now to prevent damage from ice dams builders now like to install ice and water shield under the shingles and on top of the sheathing. If water does back up  the sheathing and home are protected.

Here is a short video from Grace the makers
of Ice and Water Shield. Although this is important
to have, it is not preventing the ice dams from
occurring. Heatloss is the issue, and that is what
you should focus on along with proper ventilation.

So everything we have seen and discussed has lead to visual clues in this case on why water is leaking in where it shouldn't be. The first clue was at the front door. The wall between the front porch should not have water running down the siding underneath the porch roof.

When I went on the other side of this wall the moisture stains where just appearing . You could almost see them growing both in the wall at the top and the bottom.

Luckily the only areas in this condo that had moisture getting into the walls was here in the garage wall next to the main entrance. The home did have ice dams on other parts of the roof but because the pitch was steeper and they where not complete the water was able to drain around most dams.

The bottom line is, this is just one example and most of the defects here were fairly simple to find. The more complex the roof/home designs the more potential issues can be hidden from view. Thermal imaging is not X-ray vision. But if your thermographer has a good understanding of thermal dynamics and building construction, he should be able to diagnose the issues that cause the ice dams. This is the first step to fixing and preventing them for reoccurring.
When it's time to hire a thermographer make sure you ask about there experience and if they have had any formal training. There are many companies that offer online "certification" courses. There is no substitute for formal hands on classroom training and experience. Also the quality of the cameras can come into play as well. I see alot of people that claim they are thermographers and "certified" only to have the company images on there websites. There are different detectors and image quality associated with different cameras. If they purchased a 5000.00 dollar camera you most likely are going to be getting the image quality on the lower end. This might be fine for your specific needs or it might not be. Ask for samples from there camera and compare the images to others. Depending on what you are looking for this can make a very big difference. Since there is no national certification for  thermographers, my only advise is to ask if they are in compliance with ASNT. ASNT  stands for the American Society for Non-Destructive testing. They have very specific guidelines for certifications and testing. Among those that are professional thermographers  this is the most recognized credential. All large corporations for example that may  use or have infrared needs would most likely use ASNT compliant thermograher.

If you have any questions or comments feel free to shoot me an E-mail
I am not perfect, so if you found a mistake let me know.
Ice dam Diagram
Protection against ice dams.
Ghosting or stains on drywall
Condo with ice dams
Attic space with both fiberglass batts and blown in loose fill.
Chase open to attic.
Attic hatch not insulated.
Large chase allowing heat loss.
Non IC rated recessed light
IC rated recessed light.
Air sealed and IC rated recessed light.
air inflitration at recessed light.
Poorly installed insulation
Missing insulation
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Water backing up under roof.
Water getting into wall.
Moisture in wall from poor flashing detail.
Moisture getting into wall from ice dam.
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