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Solving The Case Of An Imperfect Air Barrier

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At TAG Home Performance, we were contacted five years ago by a physician who had built his dream retirement home. It was on a 50-acre parcel of land with beautiful woods bordering a pastoral setting, providing the house with magnificent views.  The home had been constructed by a prefabricated log home manufacturer and had spectacular cathedral ceilings and floor-to-ceiling windows facing south.

There was just one small problem: giant icicles were forming at every valley, edge, and roof/wall interface.  He had struggled for almost a year working with the builder to try to correct this problem.  He found TAG by doing research online, searching for companies with experience in solving this type of problem.

Our first visit with the homeowner was very informative.  He had available for us a copy of the plans and was able to describe in minute detail the various problems he observed, giving special consideration to the severe ice damming that was occurring and high humidity levels throughout the home.  It was easy to see the ice damming that was occurring, as we were fortunate to visit in the middle of a typical Central New York winter (cloudy, cold, and snowy). Given the stack of wood being stored inside the home, along with the design of the log cabin, we were not surprised by the humidity problem. I told the homeowner our auditor would conduct a thorough audit of his home including thermal imaging, I would review his plans, and we would be back to him with our analysis within a week.

The review of the plans revealed several important factors. First, the cathedral and flat ceiling insulation values where substantially below code requirements.  Second, the air barrier and thermal boundary weren’t in alignment or continuous. Third, the high-velocity air distribution system had been installed outside the envelope and wasn’t insulated as required by code.

The auditor confirmed multiple disconnects between the thermal boundary and air barrier.  He also confirmed insufficient insulation levels for the high velocity air distribution and higher than expected duct leakage from this same system.  Thermal imaging also confirmed substantial air leakage issues with the envelope, especially in the areas where icicles were forming.

After numerous internal discussions, we recommended targeted air sealing, duct sealing performed with Aeroseal, and installation of a whole house dehumidifier.  The homeowner agreed to all of our recommendations and we proceeded to implement them.

Several months after we had completed our work and tested out, we contacted the homeowner to see how things were going.  We wanted to know what level of success we had achieved in reducing the ice damming and controlling the relatively humidity level. (We had communicated carefully to set his expectations fairly that we didn’t think we could completely eliminate the ice damming, but we knew we would substantially reduce it.)

The homeowner indicated the ice damming was almost completely gone, the home was more comfortable, and the amount of fuel oil he was using had dropped as well.  He had also taken our suggestion of moving the wood pile to the outdoors (which we believed was contributing to the higher-than-expected humidity levels).

In our experience, we’ve found that log homes and cabins often receive special treatment from local code officials.  It can be difficult to construct them in a way that they’ll be in compliance with energy code, but with some creativity and ingenuity it certainly is possible.

So next time you’re faced with icicles and ice dams, locate the holes in the air barrier and disconnects between the air barrier and thermal boundary.  Identify them, repair them, and earn a customer for life.

Ellis Guiles

Posted In: Building Performance, Residential Buildings

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