A: There are too many variables involved in a major remodeling project or room addition to come up with an average square foot price or expect a contractor to give you a firm free estimate. Not only must you consider structural aspects, such as load bearing walls, location of plumbing and wiring, and possible changes to the roof line, but it will also depend on what kind of materials you want (Custom or pre-manufactured cabinets? Corian, tile or Formica countertops? Carpet, hardwood or vinyl floors? A whirlpool tub? Double sinks? etc.) Home Advisor has an article which explains this (just type "Free Bids" into the search box.)

Contractors may be able to give you a "rough" or "ball park" bid based on what you think you want, but no one can give you a firm bid without working from a set of plans and specifications. The best way to get a reasonable price is to pay a contractor or designer to draw a set of plans and specifications and then collect competitive bids on it--preferably from at least three different contractors. Your designer will contact other professionals such as structural engineers, as needed, to draw plans that will meet building codes in order to apply for all the necessary building permits.

Consider hiring a building designer, residential designer, or architect who specializes in residential remodels/additions. These specialists are trained to discuss your priorities and budget and design and draw your plans, including a list of specifications listing the materials you want in detail (by brand name, model number, etc. if possible). Then you can give those to about three different contractors to bid. You could also interview some design/build contractors who could oversee it all.

Visit Home Advisor, and type "Get Design Help for Remodeling or a New Home" into the search box to read an information article explaining different ways to find the right professional(s) for major residential projects.

Then you can enter service requests for whichever professionals you want to talk to, such as "Architect" "Building Designer" "Interior Designer" and "General Home Addition" (to find a Design/Build contractor) and be matched with the ideal service professional in your area.

by Kathy Maynard, reprinted courtesy of HomeAdvisor.com