Gaines Group Architects

Building Science Issues Identified – Moisture Problems With Wood Windows

Building scienceHere is the picture I posted recently about why every home needs a building science specialist. There is visible evidence of long-term moisture issues in the corner of this all wood window(discolored wood in the corner). The home is located in Central Virginia on a wall that is directly impacted with most local storms. There is wall paper on the inside of almost all walls.

The initial scope of work was simply to replace the windows. Little did I know the full extent of the damage that would be uncovered. The wall paper was acting as an air and moisture barrier on the inside of the wall. There was another vapor barrier inside the wall behind the drywall. Once the moisture got into that space, it had to dry to the outside. It could only dry to the outside if conditions were exactly right. This led to an incredible amount of damage that could previously only be seen in the corners of the windows.

Here is what we found.

Building scienceBuilding science

Building scienceBuilding science

The scope ended up rebuilding the wall structure, insulation, drywall, house wrap, flashing, paint… To say the least, a lack of understanding of building science in this 20 – 30-year-old house – destroyed the house.

energy recovery ventilator

The air within your homes can be up to 10 times more polluted than the air outside.

Air within your homes can be up to 10 times more polluted than the air outside.

Building science is tricky to get right if you understand holistic design strategies. If you don’t address these complicated issues, you are in deep trouble. (note: most people don’t understand building science basics)

Our homes for years had no insulation in the walls, no conditioned air, and they lasted for decades with no issues. Born from that history the phrase “You don’t want to build your house too tight, needs to breathe.” The houses leaked air through every crack in the walls, roof, and floor. We then added insulation and conditioned air (most don’t have any ventilation through the mechanical system). This made our homes more comfortable, but created a tighter building envelope. These tighter homes trap air inside the home that is being filtered through the attic, attic insulation, crawl space, and walls as opposed to being ventilated through the HVAC system filtration system. This has led to an indoor air quality issue, as the “fresh” air is not fresh at all. It is full of moisture, mold, and particulates. 


HVAC stands for Heating, Ventilation, and Air Conditioning. We need to use ventilation to solve the moisture and air quality issues we face in current home construction. This whole house ventilation strategy is only successful when done through design including a holistic understanding of building science. Ventilation is impacted by number of people living in the home, way of life, the type of insulation and windows, the type of mechanical system, and even interior finishes. There are many ways to achieve a proper ventilation system in your home, however, it is often overlooked or not included by your mechanical contractor. This should be a primary consideration for every home that has a goal of having a healthy indoor environment.

For more information on HVAC systems read here, here.