Estimating Rehab Cost Per SQFT

[Doug P.]

Reading the book Flip they have a rule of thumb chart for quickly estimating the cost per SQFT of rehabbing or remodeling a home.

Here is how they chart it.

Standard finish rehab - $15
Designer finish rehab - $18

Standard finish remodel - $25
Designer finish remodel - $30

Is this accurate or something anyone here uses for a quick idea of whether a property is worth further pursuing?

Also in the book I can't tell if they include new floors in a rehab but I assume they do.