How do you calculate repairs/maintenance?

[Collin Wong]

When doing my analysis of a property, rental income is easily verifiable as well as property taxes, the cost of insurance, etc. However, I'm not sure what figure to use for repairs/maintenance as it can vary depending on what breaks down. I'm looking in the Denver area and a lot of the buildings are fairly old (50+ years). Even though they may have a solid rental history, budgeting for repairs makes me nervous.

[Jaime Rocha]

I'm interested in hearing from others' perspectives. If I don't have a contractor or someone with experience with the rehab, I try to give a best guess based on the following formula.

Square footage of the house * Rehab Factor (e.g. 5-12 depending on the severity of the rehab).

ex. 2000 square foot house that just needs cosmetic (paint, carpet/flooring etc) would be a 5 rehab factor so I would estimate
2000 * 5 = $10K

same house with repair work and updating
2000 * 12 = $24K