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When building a new house you have the opportunity to do it right. You will probably never
have this opportunity again so it is important get the envelope air tight and well insulated
during construction. We feel that a combination of dense packed cellulose and closed cell
polyurethane spray foam is the most cost effective way to achieve this goal.
The recommended insulation values for this climate zone are R49 in the ceiling, R20 in the walls, and R30 in a floor over a cold space. There is an exception that allows R38 in the ceiling if the full R38 thickness extends over the top wall plate. The interpretation of this varies from town to town so you should always check with your local code enforcement officer. If you plan to have cathedral ceilings in part of your new house, this interpretation can make a significant difference in the cost to insulate the structure. We can exceed the R38 requirement in a 2x12 rafter with cellulose. In order to achieve R49 in a 2x12 we need to use closed cell foam which makes the cost 2.6 times higher!
The Energy Star air tightness requirement is less than .5 air changes per hour natural. A house built to this standard will probably require some amount of mechanical ventilation to provide fresh air for the occupants and remove moisture. A Heat Recovery Ventilator (HRV) should probably be included in the design. Also, naturally vented combustion appliances will not operate properly and should not be used.
Here are some pictures of a typical new construction installation. You can click on any of the images for a larger view.