Great Time To Start Thinking About Insulating

With spring coming insulation is not on the mind of a lot of people. But spring is a great time to get up in the attic, before that summer heat comes and install an additional layer of insulation to help keep the summer cooling bills down.

I think the best website for energy savings information is http://www.energystar.gov/. Simply put, whatever you need or want to know, you can find it here.

A much simpler, right to the point web site that will give you recommended insulating levels by zip code is http://www.ornl.gov/sci/roofs+walls/insulation/ins_16.html


In this area of the country the recommendations for insulation are;


Attic ---------------------------R 38


Wall ---------------------------R 13


Floor --------------------------R 25, Over Unheated Space


Crawl Space Wall ----------R 25


Basement Wall Interior ---R 11

The above recommendations are insulation levels that balance the actual cost of insulating and the return in energy savings.


Two methods of installing additional insulation in your attic are fiberglass batts or blown in insulation, either cellulose or fiberglass. In the fiberglass family batts give you a slightly better R value per inch coming in at 3.1 to 4.2 per inch and blown in fiberglass about 2.3 to 2.8 per inch. Cellulose is only available in loose fill and gives you about 3.0 per inch. If your choice is fiberglass batts and the existing insulation is even with the top of the existing ceiling joists then roll out 24” wide unfaced batts perpendicular to the existing joists. Doing it this way will physically cover the joists and seal any existing drafts. If the existing insulation is lower than the top of the joists add insulation until it is even with the joists and then begin the cross layer.

If you choose to use blown in, either cellulose or fiberglass make sure you install the depth gauges that you bought when you purchased the material, these will help you blow the material in evenly.


In either case you must first make sure that all electrical boxes have the proper covers and are sealed. Do not cover any light fixtures such as can lights.


One other caution is not to block the flow of air from the eves to the ridge of the house. The lower the pitch of your roof the easier it is to block the flow. Take a minute to study the drawing so you understand how air flows through your attic.

Keep in mind that houses need to breathe. The air in your home needs to change to keep a healthy indoor air environment. The measurement of air changes per hour ACH in older houses can be 1 to 3 whereas a newer tightly built home can be in the .5 ACH range. Trying to fix a target number of acceptable air changes is nearly impossible because of the wide range of pre-existing indoor air contaminants and pollutants. Factor into that an individual person’s sensitivity to these pollutants and you can see there is no way to recommend a level that would work in all situations


A great online source for understanding the basics of household ventilation can be found here http://www.nyserda.org/publications/guide.pdf


Also remember the better you home is insulated, the more critical controlling the humidity level becomes. We will talk about indoor humidity levels in a future posting.