Evaluating a Property with a Carriage House

[Donald S.]

I'm looking at a deal that is 3 bed/2 bath but that includes a main house w/ 2&1 and a carriage house with 1&1, the property also has a 2 car detached garage. I understand using the BP calculators to help with determining numbers, just need some help on figuring out some of the inputs. 

My question is when determining comps and rent comps should I look at SFH that are 2/1 and SFH that are 1/1 and just combine the 2? I can tell rent is the area for a normal 2/1 SFH is ~850 a month for the house size and the quality it will be after I fix it. And rent for a 1/1 is ~ 400-500/month, so would I just combine the 2 and estimate 1250-1350, or go conservative at 1150, etc...? Anyone have experience renting a property like this?

Also when determine comps for ARV how should I determine comps if this is the only home in the area (and a large area) that has this type of setup? just find an 1100 sq ft house and 700 sq ft house and do some conservative combining again?

Any help would be greatly appreciated. 

Thanks, Donald