I would like to launch into a series of topics for discussion starting with foundations and working through each phase of a project to completion, but first to launch this endeavour I would like to do something to honor the current weather conditions and how it affects us. This is a sample of the topics to come, please feel free to submit any topic suggestions that you would like discussed during this series.

Attic ventilation and insulation is something most people never have much cause to think about, for single family and multifamily structures already completed there are ways to check if your attic is functioning properly, for new construction the same checks apply. Why is this important? 1. Heating & cooling loss = $$ out of your pocket 2. Damage can occur from ice damming and condensation 3.dry rot from insufficient venting. So what causes these issues? the concept of the conventional roof system is to insulate the ceiling (currently R-38 for attics is code) and vent the space above. Keeping the temperature of the attic close to the same temperature as the outside is very important.If the outside air is colder than the attic then cold air enters the attic through the improperly vented roof system it hits the warmer air and freezes any moisture in the warmer air. The other thing that happens is any metal (roofing nails, cast iron vent pipes etc.) that penetrate the roof into the attic do what is called thermal bridging, you may have seen something like this on aluminum windows where condensation freezes on the inside of the frames then melts creating a mess, roofing nails through the roof will rust and eventually allow water to leak in.

What’s the solution? first check to see what the depth of your insulation is, bat and blown in insulation is typically R-3.75 per inch so an 8″bat or blown in depth = R-30 which is pretty good! Next check to see all ventilation is in place and clear (sometimes the insulation blocks off the eve vents) next make sure there is an airflow pathway such as eves to gable end or ridge vents and that they are sized properly for the space (venting charts are available), this will keep our attics cold and living space warm in the winter with proper insulation. During the summer it works in reverse, hot air is ventilated out of the attic limiting the heat gain into our homes through our roofs while eliminating dry dry rot issues. In extreme cases the damage caused requires full roof replacement, climates definately play into the “extremes” however the solutions are the same, check with a local design professional or building inspector to see what is recommended for you region.

Matt Stodola

This entry was posted by Matt on Friday, January 14th, 2011 at 3:39 pm and is filed under Field Work, Materials, Wood. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.