The Condensation Caper

It was January in Chicagoland, a gray and snowy day, when the Energy Detectives from Informed Energy Decisions responded to the call of a frustrated homeowner. The team proceeded to the scene (an ample, well-dressed eight year-old suburban home). We listened as the owners told their grisly story.

The crime? A second-floor master bathroom that dripped like a Turkish bathhouse whenever the shower was used. It was a condition that had persisted even after the homeowner made the builder add insulation in the attic and install a bigger vent fan in the bathroom itself.

How bad was it? So bad that a painter working on the rest of the house couldn’t touch those saturated walls with a ten-foot pole.

There was evidence of water stains not only on the wall against the exterior of the building, but on the three interior walls as well, an unusual case indeed. We had to take it on.

Using our handy (very cool) infrared scanner, we surveyed the bathroom walls and ceiling. In spite of all that insulation, we found 10 cold patches. We marked out the clues with color-coded painter’s tape.

Then we pulled out our infrared thermometer to determine the temperature variations within the room. On a day when it was 30 degrees outside, our inspection yielded inside temperatures fluctuating by 10 degrees between the warmest and coldest locations in the room. The case was more intriguing than we had first thought.

We proceeded to the Jacuzzi-style tub, which had been installed against the exterior wall. After removing the access panel we expose the tub’s underworld with high powered flashlights and discovered our first culprit. There was no sheetrock below the tub and, worse yet, even though the exterior wall had been insulated, the insulation was improperly installed.

Once the whirlpool confessed its secrets, we knew this wasn’t the whole story. As is always the case, more scratching reveals more "dirt".

After suiting up in protective clothing and respirators, we proceeded to our next suspect, the attic, where contractors had blown in insulation up to 18 inches deep. Tunneling to the spot where the bathroom walls joined the ceiling, we were not surprised to find under all that fluff an air and heat escape route between the top plate of the framing and the sheetrock walls and ceiling below.

This oversight also allowed cold air from the attic to fill the walls of the bathroom below. When cold walls meet moist heated air…You got it: condensation.

But wouldn’t all that insulation in the attic above the bathroom stop the cold air from seeping into the walls? Here’s a little known fact all homeowners need to know: fiberglass insulation does not stop air movement.

The picture was becoming clearer. It was not pretty. One important clue we garnered from beneath the tub was the improper way the insulation had been applied. By turning the tabs in and stapling the fiberglass batts on the inside edges of the 2x4 stud, there was a gap of about 1 inch between the insulation and the sheetrock. Combine that with open gaps at the top of the framing and what do you get? —A wall full of cold air.

At this point, we had two major offenders in hand, both of them immediately associated with the bathroom damage. Case closed? Not quite, because here’s where intrepid detectives catch a second breath and continue. It’s what sets them apart from the workaday flatfoot.

We suspected another accomplice: an additional cold air pathway was supplying a huge temperature differential to the entire upstairs, thus compounding the master bath problem. We had to widen our search.

At the opposite end of the house stood the attached garage. Sure enough, lurking under the garage roof and above the garage ceiling, we found the mother of all framing cavity leaks. Five or six of the joists that supported the second floor jutted into the garage attic, which was open to the outside via many vents. The space around the joist ends had not been closed off or air-sealed. Instead, the builder had neatly placed (you guessed it) squares of fiberglass batt between the joist ends.

Removing one of the fiberglass batts and shining our flashlight on the subject, we could see all the way to the other side of the house. The same situation existed under the front porch roof and on a second floor overhang on the opposite side of the house, leaving the entire space between the first floor ceiling and the second level floor filled with cold air. This was bad. The house was clearly a victim of gaping holes in its pressure boundary.

Adding insult to injury, a horizontal duct chase located beneath the second floor joists ran almost the entire length of the house, connecting most of the other hollow framing cavities of the house. The builder had apparently decided that this duct chase could serve double duty (translate: cheap) as the return air duct for the furnace.

Not only was the entire second floor exposed to cold outside air, but so was the HVAC system. With the furnace pumping air into a pathway that was being constantly cooled by outside air, the system was working twice as hard as it needed to achieve much less than desired results.

Now that we had diagnosed the entire scope of the problem, we outlined for our homeowners the steps they could follow to fix the problem.

The sad moral to this tale is that the weaknesses in this home could have been avoided with very little expenditure and effort on the part of the builder. This builder, it seems, was much more skilled at making the fast buck than in building for energy efficiency.

Unfortunately, our homeowners will now have to pursue challenging and costly repairs. Typically, it costs pennies on the dollar to avoid these problems when the building is under construction. So yes, it’s just like your mother always told you: it’s easier to prevent a problem in the first place than to fix it after the damage is done.

The Energy Detectives at Informed Energy Decisions unravel the mysteries of existing buildings, as well as oversee new construction. By adhering to standards of pressure boundary design and other energy and comfort performance principles, we catch culprits before they pick your pocket.

Call the Energy Detectives at Informed Energy Decisions today. It could be the best investment in a new or existing home you ever make.

Case closed.

Stay tuned for the next installment. The case may be yours.