Heritage Restoration, Inc.

Pressure Testing a House to Find out What is Best

The recent storms have been a real eye opener. Mother Nature not only has my attention, but my respect. As trades people, we spend our professional lives trying to keep weather out, make building’s last longer, and as of more recently, saving energy. Recent is really relative considering how much of our housing was built without energy considerations. So what can we do to save money? Start by observing.

There I was, sitting in my living room during the northeaster a few weeks ago, realizing cold wind was significantly different than the warm wind only a week earlier. As my hair blew in the breeze, I remembered that airflow could be the greatest source of heat loss in a building. While the northeaster was not a normal circumstance, the wind blowing around 50 mph showed that my 1907 house was no match for that kind of force. The problem was not the original windows with storms; rather the wind was coming through the walls. Yet houses were constructed using felt paper for over a hundred years or nothing before that, and even the newer house wraps are not designed to stop intense airflow, especially without sealing the seams or being peppered with holes. And since the wind was so strong and cold, the house felt like I was sitting in a tent.

I have choices, but first I had to do some research. I completed two blower door tests on the house, which is like an artificial northeaster. The first blower door test was the day after I bought the house. There were so many penetrations and holes that the house could not even be pressurized, which means money is being wasted. The test revealed the biggest problems were in the roof and the basement. There were missing foundation stones, a missing interior door inside the basement bulkhead, loose basement windows, an attic with more gaps than a picket fence, and exterior doors without weather stripping. Perhaps the most surprising was the original double hung weighted windows were not problem. What I thought was the problem and was not the problem.

I spent the next year chipping away at the holes. Since we were redoing the raw attic space, I chose spray foam insulation from the plate to the ridge. I filled in the foundation holes with mortar and stones(which by the way were under the porch and behind the oil tanks so I could not see them). I installed silicone bulb weather stripping inside a groove I made for the doors. I installed a basement door inside the bulkhead. I reset all of the basement storm windows and sash.

The second blower door test actually pressurized the house, with a 40% improvement to the airflow. Great right? Sure, until we get 30 degree 50 mph winds, and I am reminded of how the house is not perfect. What else?

Some may suggest blown-in insulation in the walls. Straight blown in does little to prevent airflow, and it can act like a sponge from direct water, condensation and excessive airflow that leaves behind moisture. I have seen houses with older blown-in settle over time, leaving huge gaps, or they just miss spots. I am also not a big fan of blown in since when we do demolition or have to fix some framing, it can be very unpleasant. Now there is dense pack blown-in, which uses high pressure to reduce airflow and make sure the cavities are filled. These are OK for some houses, but without the proper building assembly of a sound, properly installed building paper, I worry about air flow and moisture, which are ingredients for future exterior paint failure and rot. I could tear off all of the siding and properly paper the house, but that would use more energy and money than I am saving. I could tear out the plaster and insulate, but then all of my trim comes off, I loose character, and again, I am spending more than I am saving.

There is a line for me, and for many others who assess, inspect and retrofit buildings for greater energy efficiency. There is always a balance between saving energy by forsaking embodied energy (the fuel/energy expended on things that already exist), and what the long term repercussions are to the building. Truthfully, I may never be done with my house. Perhaps I will wait until the siding dies, about 10 years or so, wrap the house properly and reside. Maybe then I will blow in insulation. Or maybe by then I will be creating my own energy. Or maybe I will just sit closer to the wood stove, and enjoy my old house.

Leave a Reply