most common budget miss in rehab

[Eric Bretzman]

So what are the most common rehab budget items you miss on and why does it recur? I'm not talking about not knowing to budget for holding costs and things that should have their own line item. I'm thinking about the items you budget X$/sq ft or time and materials or however you do it with your experience and yet that particular line item goes over budget an inordinate amount of times? Maybe it is work you are actually doing or you are hiring out but either way the same couple things end up more than they really should be.

For instance, you can predict carpet costs well but half the time the tile guy runs over due to discovering extra surface prep is required. Or you always get the interior paint estimate close but exterior is 20% over what it could have been because more times than not there is some rotted trim that needs replaced and primed that couldn't be seen in advance.

I put an overage percentage in my calculations but it is global. I don't know enough to guess which hole the whack-a-mole is likely to pop out! Those of you with more rehabs under your belt may be able to pass on the most common budget hot spots. Is there a pattern? Have certain trades been raising rates faster than others recently?