Thursday, July 23, 2009

Why your home needs to breathe

A student recently told me he had his house evaluated by an Energy Analyst who told him that attic ventilation wasn’t important. After my outburst of ‘that’s a load of *&#! I explained the importance of attic ventilation and decided it would be the topic for my next blog posting.

I spend a lot of time reading and studying about residential building systems as a home inspector, handywoman and teacher to other homeowners. It is important to understand that there must be a balance between attic ventilation and the other systems in the house. It is not necessarily a more is better situation. The key is adequate ventilation.

The following information contains facts about the importance of ventilating your attic space as related to energy efficiency, indoor air quality and structural integrity.

Ventilation and cooling efficiencies.
Cooling your home is one of the more difficult systems in your home to control. The cost of cooling your home can differ significantly from your neighbor’s home simply by virtue of a few simple things. One of the most important is your roof and attic space. In the book, Residential Energy (cost savings and comfort for existing buildings), it is noted “ Homes with reflective roof coatings, at least R-19 insulation and good attic ventilation, may experience two-thirds less solar heat gain than those homes with darker roofs, little insulation and poor ventilation.” The less solar heat gain the less cooling costs incurred.

Indoor Air Quality
There are a number of things in our homes that contribute to polluting our indoor air; combustion by-products such as carbon monoxide and nitrogen oxide; volatile organic compounds (VOC’s) from solvents, cleaners, paints & furniture; Biological particles from pets, plants and other critters in our homes. The only way to handle this indoor air pollution is to have proper ventilation of our living space to allow regular air exchanges with outdoor air. One of the key components to this air exchange system is the ventilation in our attic space.

Structural Integrity
Ventilation in an attic is very important to maintaining the structural integrity of our roofing system. The ventilation allows moisture that accumulates in the attic from bathing, cooking and other activities in to dissipate. It also reduces heat buildup during the summer months. If the attic is inadequately ventilated moisture can cause numerous problems including delaminating of wooden roofing materials, water streaks on interior walls, peeling and flaking of paint and damage to insulation and other components. The heat and moisture build up in the attic space can also cause premature wear of the roof covering severely reducing it’s life.

Sources:
Residential Energy – cost savings and comfort for existing buildings – John Krigger, Chris Dorsi
The Complete Book of Home Inspections – Norman Becker P.E.
Canadian Housing and Mortgage Corporation http://www.cmhc.ca/en/co/maho/index.cfm

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