Often the R-value of insulation is touted by builders and there is only one way to check up on builder insulation claims.
You have to look. I measure it!
How does insulation work? Insulation blocks or traps air. R-value, or resistance value, expresses the thermal resistance of the material used. The material blocks the passage of heat toward the cooler place. Heat seeks cold.
Every insulation material has a resistance value attached. And they differ per inch! R-value is calculated by multiplying the material's stated resistance value per inch by its depth. (That's the easy way. There are ways using division, but multiplying is easier for me.)
So, if a builder claims in the sales literature that they will be blowing loose, fiberglass insulation to a depth of R-30 or R-38 into the attic space, the easiest way to check that is by measuring depth.
HERE IS A RECENT TREND I AM SEEING IN NEW CONSTRUCTION. IT IS A CHART PLACED IN THE ATTIC SPACE, VISIBLE FROM THE ACCESS HOLE OR LADDER. IT SHOWS R-VALUES FOR INSULATION BASED ON THE SQUARE FOOTAGE OF THE ATTIC AND THE NUMBER OF BAGS OF INSULATION BLOWN INTO IT.
WHY DON'T I LIKE THAT? BECAUSE THERE IS TOO MUCH SLIP BETWEEN CUP AND LIP. WHO CALCULATED THE SQUARE FOOTAGE? WHO MADE SURE SO MANY BAGS WERE BLOWN INTO THE SPACE? IS THERE ANY FIBBING?
This new construction is supposed to meet energy standards that desire R-38 in the attic space. The chart at the top of the attic access ladder had a number circled for square feet and for number of bags used for the space. Therefore, it claimed, the R-value is 38.
Yet when I measured the depth of the insulation I got an average depth of 9".
That is not much insulation!
R-38 is a good value! 9" of loose, blown-in fiberglass puffs is not!
SO I DISPUTE THE ENERGY CRITERIA USED TO DETERMINE THE R-VALUE! THIS CHART SIMPLY CANNOT BE USED AND BE CONSIDERED ACCURATE!
Blown-in fiberglass puffs have a stated R-value of 2.2 to 2.5 per inch.
It is more toward 2.2 for sure, but let's calculate the R-value.
2.2 x 9 = 19.8 R-value
2.5 x 9 = 22.5 R-value
THIS LEADS ME TO QUESTION THE ENERGY-RATING AGENCY (OR AGENT) CHECKING OFF THE BOX THAT SAYS THIS INSULATION IS SUBSTANTIAL ENOUGH. WHAT, THEY LOOK AT A CHART AND SAY "YEP" AND CHECK A BOX?
This is not sufficient insulation by any measure!
Topping off my beef with this insulation, beside the wonderfully-installed attic access ladder, apparently the guys needed a spot for some tools.
So what better way to create a little work bench than to scrape away the insulation!
Oh, and "forget" to put it back.
Notice that no dam has been created high enough to contain insulation from falling down the access hole. So all around that ladder the insulation will be NECESSARILY THIN!
My recommendation: new construction inspections investigate many things. They are always conducted after the supervisor has made his "final" walk around to insure that the house is completed and after the County has given final approval to the house. In this case it was done after the energy "professional" rated the house as RESNET compliant. All those other approvals MUST be taken with a grain of salt. HIRE A HOME INSPECTOR!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560