90% of “ad-on” work can be avoided in the bidding process. Always write out a detailed description of the work you are looking to have performed, and provide it to ALL contractor’s bidding the job. If the scope changes during a “walk through” with one bidding contractor, be sure to call other bidders to convey the changes. You will only be able to make an informed decision about what you are paying for if ALL bidders are providing estimates on the same line items and level of quality.
Any contractor who missed things in the walk through that was noticed or mentioned by another contractor should heighten your awareness about both contractors. The one who missed it may be looking for extras later or not as capable as he let on; the one who pointed it out may be the person you are looking for despite the price difference.
Always get at least three similar estimates. It is your responsibility to choose the right person for the job. You can only do this by committing yourself to the bidding process on the front end. The three bids should be from companies of equal caliber – same size, same qualifications, same quality clientele, etc.
When getting an estimate, begin your interview process on the initial phone call. If the contractor does not answer the phone or return your phone calls, cross them off your list and move on. Do not look back.
Ask as many questions as you can before scheduling an estimate. Your time is valuable and you can save much of it by pre-screening people before you meet them.
If a contractor cannot provide any references for the specific type of work being bid, he may not be right for that project. Be sure to call the references when they are provided. If the contractor, or home remodel company does not have reference from similar past work, it can mean that they either have never done that specific type or job, or executed it with poor quality. Either way it is a red flag to be wary of. If you live in the south-western United States, a san diego home remodeler is a great place to start due to the high concentration of high value homes in that region.