Portland, Maine Energy Audit in 2011:
Balancing energy efficient solutions within a home and maintaining a healthy home should be the goal within every energy audit. In dealing with retrofit scenarios, especially in New England homes, moisture management should be one of the most important focal points. If a home owner air seals and insulates a home with moisture issues, mold can grow, and in the worst scenarios it can overwhelm a home.
This clients home offered high moisture within the basement and some classical heat loss and mismanaged air flow scenarios, this post addresses the moisture concerns.
he photo above shows a cold water line generating condensation due to the high moisture levels in the basement, we see this in many older homes with that “musty” basement feel. This scenario is exactly the same as condensation on a glass of cold iced tea in the summer time. The Relative Humidity in the air is higher than the temperature of the surface, leading to condensation and puddles of water on the basement floor. If you lower the RH enough, then the condensation issue goes away.
So what can lead to that “musty” basement feel and the subsequent condensation on the pipes? In this scenario the home had water leakage through the foundation wall (above) as well as mismanaged mechanical ventilation (below). Beyond standing water under the oil tank, the legs are also rusting out as well – never a good sign as this oil tank really is not that old.
The above photo is a picture of the dryer venting…right back into the basement. This is NEVER a good idea. Under no scenario, unless potentially you live in the desert, should you ever proceed with a solution like this! Some people believe that you can harness the heat from a dryer by venting is into the basement (shown below – from a different home). For whatever small amount of heat that is generated from doing this, it is not worth any amount of moisture.
So, how do we fix this? We know that condensation is occurring due to high levels of moisture in the home and before this home owner can ever think about large scale air sealing and insulation to decrease energy bills and improve seasonal comforts, they need to manage this moisture problem. That said, there are 3 different approaches that can be recommended.
- Exhaust the dryer vent outdoors – no questions asked. Do not install a heat diverter (shown above)
- Improve exterior grade away from the house in the corner where water is leaking into the home OR install a french drain within the basement leading to a sump pump that expels water to a low side of the exterior grade - make sure to seal the top of the sump pump so water is not exposed
- Install mechanical moisture management system: dehumidifier that expels/pumps water directly outside or potentially into you waste-water pipe (if code acceptable). (set at 55-60 RH in the fall, winter, & spring)
- If not gutters exist, run gutters to low side of the home and install a down spout that leads as far away from the home as possible.
Once there is no longer standing water and no more pipe condensation, then it should be safe to air seal and insulate the home.