There are many variables in remodeling a room in an existing home; many of these cannot be seen until some demolition work is done. So you want new flooring in the kitchen and you have estimated the cost of the flooring based on square footage. But when the contractor removes the existing flooring, he finds water damage to the sub-flooring. Was this included in the estimate?
You have the existing, dated lights removed and new lights wired and installed. This will require some wall patching; are the walls textured? This requires matching the existing texture before painting. Not a simple painting job.
Here is another item that is rarely considered in the cost of a remodel – how will the demolition materials and appliances be disposed of? This costs money and each type of material must be disposed of in the proper place.
There is a nice article that outlines most of the issues that add to a remodel cost that the average homeowner may not have thought of, at kellyskitchensync