How Much to Estimate Maintenance on Rental Property - Los Angeles

[David Tipton]

I've started trying to value multifamily deals, but having some difficulty knowing what is reasonable to estimate for maintenance (i.e. repairs and capital expenses).  

Does anyone in the LA area have a general "rule of thumb" for estimating maintenance costs, at least for the initial evaluation stage?  Is there a certain percentage of the rent?  Flat dollar value per door?  

I would like to have a conservative estimate, but want to avoid being so conservative that I make every deal look like a loser.  Any advice is greatly appreciated.