Adjusting Good Condition Comps to Refurbished Subject Property

[Brady Margadonna]

What is everyone using to calculate this?  I am in the Boston area and currently using $15 per sq. ft. for adjusting a home in good condition to the refurbished subject property.  For example, if the comp sold at $100,000 and is in good condition at 1,000 sq. feet, I am adjusting this comp by adding (15 x 1,000) $15,000.  If the comp is in average condition, I am adjusting by $30 per sq. ft. and so on.