Calculating ARV, hung up on square footage?

[Alexander Ludena]

Hello everyone, as of late I thought I was pretty confident on my ARV analysis skills, but lately I find myself meticulously adhering to square footage as I look at comps a little too much.

I suppose the best way to explain where I'm stuck in calculating the ARV is to provide an example.

I have a ranch and I'll like to add a full second level. Additionally, I will pave part of the backyard to have enough space to park one or two cars. Let's say for discussions sake the property is 1,000 sqft and after rehabbing it we are now at 2,000 sqft.

Now my question is when I look at comps, I must look at comps that are around the 2,000 sqft since we have now increased the square footage of the subject property correct? 

Thank you in advance.