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?