Some Simple Facts to know about Insulation
I am just going to run down some facts that you may not know about insulation and are useful to understand.
Insulation, in general terms, is measured in R- value or a measure of the thermal resistance to heat. Different building materials have different R - values and therefore some are more efficient than others.
Today's residential building code requires minimum insulation levels that are based on what zone (how cold and how hot the average temperatures get) you live in. We live on the border of zone 3 and 4. Mooresville is actually zone 4 and requires stricter insulation requirements.
So let's break it down:
- Floor insulation into crawl space: R-19 (6" of rolled fiberglass)
- Walls: R-13 (3.5" of rolled fiberglass)
- Ceiling into attic: R-30 (Approx. 9" of blown insulation)
- Single pane: R-1 to R-2
- Double pane: R-3 to R-4
- Energy Star: R-5 to R-6
Remember, these are only the minimum required levels and an older home typically has far less insulation than this. Today's Energy Star requirements are in fact much more strict. For instance, attic insulation is R-49 or 15" to qualify.
Other Important Info
Insulation must be touching what you want it to insulate in order to be effective. So the rolled fiberglass insulation in your crawl space must be pushed up to the ceiling or it is not doing much. The reason is that it is not an air barrier.
An exposed wall with rolled insulation, such as a bonus room knee wall is about half as effective as the same wall with a 1" foam board added with the joints sealed.
Many attic access doors are not insulated at all or very poorly insulated. Adding foam board or a zippered "tent" will significantly improve the R-value. If you have any questions about this, please give us a call and we can point you in the right direction.