Estimating Rehab Costs - Quick Formulas?

[Ben Valentin]

I know the best answer - "Read 'The Book on Estimating Rehab Costs' by J. Scott". I promise I will read it, I just haven't been able to purchase it yet. 

Other than that, are there any quick rehab methods out there? I've heard some say estimate $8-$10 per square foot, and I've heard others say $20-$60 per square foot. Are any of these formulas valid?

I have zero background in construction or rehabs. I'm looking into both rehabbing and wholesaling, but I know I won't always have the chance to have a contractor come in and do the bids or estimates BEFORE I make an offer to the seller. 

I want to go the route that some of these guys are saying and just get a deal under contract, but rehab costs are the biggest thing holding me back from making offers. Comps, sure. I can market and I can negotiate. I just have no experience with construction. 

I appreciate any advice!

[Jassem A.]

If you know the price of the materials and can do the work yourself then it's whatever materials cost plus how much your time is worth to you. There's an app you can get for estimating roofing materials needed simply by taking a picture of the roof. I'm about to have a metal roof done for about 1200 or so in materials and will probably be 600 or so labor. I think the metal roof panels were only about $0.50/sqft.