Saves 30% off Fuel Bills
JM of New Bedord Co. has been insulating thousands of houses since 1951 and those that just insulated their attics saved on average 30%
Should I Insulate the floor of the attic or the rafters?
Insulating the floor is a very good option if available, it enables you to easily get to the Heat resistance code of R38. It also leaves open the option of raising that value higher in the future.
By insulating the floor of your attic you cut off that attic space and no longer heat that area.
This also allows adequet ventillation for your roof which will last longer because of it.
Insulate Rafters with Vents
Insulating Rafters with prop-r-vents is good to create more conditioned space without loosing the roof ventilation.
The only down side to Prop-R-vents is that the actual vents take up an inch of space which reduces the potential R-value of that space.
You also end up heating more space which leads to higher fuel bills.
Insulate Rafters without Vents
When you make a "Hot Roof" you are actually stopping the ventilation that flows underneath the roof deck.
The problems with hot roofs are that they dramatically decrease the life of the shingles. The insulation behind the shingles trap the heat within the shingles, thus the sun bakes the shingles at a much faster rate.
But I use my attic for storage?
You can either...
Blow underneath the flooring and dense pack the insulation into the rafter space
Build up the flooring with 2X6 to allow for extra space. Run boards perpendicular with existing joists.
Possible Attic Problems
Gaps and cracks should be sealed before installing insulation, especially when you have batt insulation.
Heat will penetrate the low points in insulation. Get the most of your insulation by having someone install it correctly.