Insulation systems or materials

I can't believe this!

"Insulation systems or materials

Enter the amount you paid for home insulation systems or materials designed to limit the heat loss or gain of your home.

Do not include the costs of assembly, preparation, or installation."

 

Obviously, the contractor who insulated my attic did not detail the bill. I suspect the cost of the insulation material is a tiny fraction of what I paid ($3,271). Same with the other contractor who later insulated the cantilevers and the family room downstairs ($1,700). I'll contact them on Monday, but I'm not hopeful I'll get an answer. Is there a rule of thumb I can apply, say 10 or 15% of the cost going towards materials?

 

Thanks!