estimating rehab costs

[Sherri Abrams]

I just looked at a home that was completely trashed. Some of the rooms needed a new ceiling. Not sure if the hardwoods can be salvaged and the kitchen and bath need a complete overhaul. I have been told several different ways to estimate rehab costs. But the one that I was told is the easiest and quickest way to estimate is to multiply the square footage by $20 or $25. That answer would be a rough estimate of the costs for a full rehab. Then the person said that if it needed a new roof add a couple of thousand dollares and landscaping another 2 thousand. Is that a good way to estimate to determine whether or not I want to even make an offer?

If there are other ways to estimate please tell me. I would like to be able to get a quick and rough idea of the costs when I go canvassing properties before I do the due diligence.