wrote:
My house is elbow shaped. Kitchen, den, living room on one side of
the
bend and bedrooms, baths on the other.
The floor joists under the bedroom side are 2x8 12" on center. I am
cutting a 23" wide roll of insulation in half lengthwise to insulate
under the house. This gives a tight fit to the insulation.

However under the den side of the house, the joist spacing is 20" on
center. I have a 19" space to fill and insulation at Lowe's, Home
Depot only comes in 15", 16", 23", and 24" widths. I don't
particularly want to use the 23" rolls since that would be a waste of
4" from each roll.

Does anyone have any ideas of how to efficiently fill this space?

Just get the 23" wide rolls or batts and cut them down to 19". Yes,
it's a pain, but the only other alternative I can think of is to use
blown-in insulation somehow. And if its the underside of the floor
joist in the crawl space you are insulating, then adding something to
hold the blown-in insulation in place is more trouble than cutting down
wider rolls.

I've been doing this in our attic that has random roof joist spacing,
ranging from 18" to 22" (old house built in 1925). Find a place to
store all the little scraps to use for something else. I store my
scraps behind one of the knee walls in the attic.

Ken