I had a budget GC tell me that my 48x48 windows are slightly off of the typical dimensions and will require a custom sized window to replace them.  

Dimensions and height of he structure are restrictive because I had to build on the site of a torn down single-car garage & its tool shed.

Do you know the average, or the minimum, dimensions of a center island?

If you give me the dimensions of the kitchen/living room and a rough floorplan drawing I could whip you up a 3d design pretty quickly illustrating what I'm talking about. 

@Tanya F.Dense/wet packed cellulose, mineral wool or hemp may be an option, but the house is old enough that it may be balloon framed or from local cut (non-standard dimension) lumber with live edge plank sheathing.  

I don't know the exact dimension, but it would be the standard size that works with the metal "H" stand that pushes into the ground. 

The microwave/oven combo quit and had to be replaced with separate units because the old dimensions were obsolete.

The foundation was a block basement, with the same dimensions as the ground floor.  

Usually you'll be able to find owner and sales histories, basic property info, assessment histories, and EXTERIOR top-down diagram i.e. drawing and dimensions of building perimeter, etc.

Best I figure so far looking how the two would interface is I can import an image or view from SU then text or dimension over it.