Running Comps: Patios and stoops

[Alexander Alguire]

I am practicing running comps and some of the properties I am looking at have patios and stoops. I read J Scott's guid to estimating ARV and know that they have different values; I am just not sure how to calculate those values. How is the square footage cost calculated? Is it the same as the rest of the house, or does it have some differing value given that its outside? Do any other factors play into the value of these?

Thank you in advanced!