Quote from @Will Barnard:
Using a price per SF for estimating rehab costs is one of the worst ways to do it as it is the most inaccurate! I have posted many times in many threads on how to perform this task in great detail. Do a search or look through any of my many posts in the past on this topic.
Essentially, you need to NOT rely on others (like contractors or inspectors) to perform this task, you need to know how to do it and after practicing many many times and using the right tools, you can eventually do it in your head in 15-30 minutes while walking through the property.
You need a spreadsheet (several free downloadable ones on the BP file place at the bottom of any thread page), fill in your local numbers for material and labor costs for each line item and then break up the home into sections. Kitchen, bath, flooring, paint, landscape, HVAC, electrical, plumbing, roof, stucco/siding, etc. Once you know the average general price for each area, you simply walk through, label your scope of work and add up the numbers. It is not rocket science but it does take lots of practice so get out there to open houses for fixers and start practicing once you have your spreadsheet filled in.
Thanks for the suggestion! I am a newbie and wonder how do you get an estimate for these each of these line items you mentioned? If I call the contractors in my local area, I would be told that they can’t give me a number and it all depends on the size of the project/current situation/the finish etc, is there a way that I can estimate these more accurately?