Estimating rehab work for newbie

[Daniel Petta]

Hey everyone, I'm just starting out and haven't pulled the trigger yet on a property and constantly refining my proforma model but wanted to seek advice on estimating rehab work.  Most of the deals I'm looking for are going to have some value add work that will need to be done.  Instead of floating some random number in my model for work that I have no experience in yet.  Wondering if folks have some actual costs for major rehab work such as new roofs, new/replace plumbing, upgrade electrical, etc.   

I know that no two properties are the same and everything is with a grain of salt but wanted to get a sense of what I could expect per square foot.  

I should mention that my strategy is to buy and hold for cash flow so not flipping so different scope of work than those flipping for appreciation.  I'm also looking at multifamily.

THanks,

Daniel