Homes that survived to be called “historic” did so because they worked; that is, they delivered a level of performance that met the owner's expectations and tolerance level without catastrophic damage to the home, pocketbook, or surrounding environment. Home performance expectations have changed and now include a desire to use less energy while at the same time realizing a level of comfort that includes air conditioning and constant temperatures in all rooms. In order to meet these performance expectations, old homes often require some “re-engineering.”
Increasing insulation will advance energy efficiency goals, reduce costs, and make a home more sustainable but by itself is insufficient, and, often, it can also upset the moisture balance resulting in unexpected mold and sick building syndrome. Improvement in moisture management design is a critically important consideration whenever energy efficiency is increased; however, many projects fail to address moisture adequately. This article will walk through the process of insulating and air sealing a house (two very different activities, sometimes combined, sometimes not), and shed particular light on how different approaches encourage or discourage moisture problems.