There’s a common but flawed perception that tightening up an older home to make it more energy efficient will make it more susceptible to mold and moisture. Nothing could be further from the truth. The few homes that have had problems share a common denominator: The contractors who worked on them didn’t understand how to get the most out of contemporary materials and construction practices. That takes an educated pro.
In ancient times—30 or so years ago—it was much easier for someone with basic construction knowledge to build or renovate a home. No more. Today, the combination of contemporary building materials and code-mandated construction practices has made the job more complex with less margin for error.
First, consider the evolution of materials. Suppliers used to sell framing lumber cut from mature trees that could absorb a lot of moisture without problems, a quality known as hygric buffer capacity. Builders and remodelers put that lumber into drafty walls where any moisture absorbed by the wood could escape before it caused problems.
But those mature trees have all been harvested. Today, a new room addition will likely be built using a combination of engineered boards and dimensional lumber cut from fast-growing species—neither of which can store and release as much moisture as old-growth wood could. To complicate things further, energy codes mandate that those materials be put into well-insulated, nearly airtight walls.
These are not drawbacks. Engineered wood offers real structural advantages, and the insulation and air sealing that are a necessary part of a major remodel, addition, or energy upgrade will make a home more comfortable and efficient. No modern remodeler or homeowner would want to do without them. The materials and insulation aren’t the problem; the problem is contractors who don’t know how to work with those materials.
That makes it crucial to hire a remodeler who understands the basic principles of moisture-related building science. Yes, good design and construction is now a science as well as an art.
Professional remodelers use bulletproof roofing, siding, and flashing that keep water out of the structure. They also know how to craft efficient wall systems that can handle the large amount of moisture put into the home’s air by a typical family (from activities such as cooking and showering) without problems.
These remodelers understand that drying potential is as important as moisture resistance, and that wall systems must be optimized for the local climate. For instance, if any of that airborne moisture works its way into a wall, it needs to dry primarily to the outside in a heating climate but to the inside in a cooling climate. The educated pro knows how to make sure that happens.
The bottom line is that the structure needs to stay dry no matter how wet the weather or how many long, steamy showers the occupants take. Back in the ’70s or ’80s, industry standard practices meant that someone could renovate a home and avoid moisture issues without much building science knowledge. That’s no longer the case.
Does your remodeling professional understand this?