Before you meet with a designer, it may be helpful to test your budget – to see if you can do the work you want to do for a price you can afford. You can estimate your construction costs based on a few simple assumptions and some average cost-per-square-foot data.

Here are some very broad construction budgeting guidelines. They are generally applicable to one or two-story, suburban or small-city homes that are less than 50 years old, and already in fair-to-good condition. Allow for increased costs in big city areas, highly desirable areas (like beach-front properties or a mountain resorts), exotic architectural styles, more deteriorated or complex buildings, and changes in the cost of living since the publication of this article (2004). If you’re working on a commercial or small industrial building, you’ll need to find cost data by talking to contractors and estimators.

To estimate the cost of your own project, select the paragraph below that best describes your scope of work, then apply the costs at the end of that paragraph to the entire number of enclosed square feet in your building, whether the work will affect the whole building or just a small area.

1. If you are just making a few repairs, for example, patching the roof (but not replacing it), replacing the furnace, fixing a few plumbing leaks, repairing windows and doors, painting, installing new floor coverings, and doing other small miscellaneous work, you can multiply the number of square feet in your home by $25 per square foot.
   
   
2. If you are doing all that and replacing major plumbing lines, replacing bathroom and kitchen fixtures (but not the cabinetry), replacing (not repairing) windows and doors, and making some minor structural repairs (a porch floor is sagging in one corner, for example), you can multiply the number of square feet in your building by $35 - $50 per square foot.
   
   
3. If you are repairing or replacing sections of exterior finishes such as brick or siding, making major structural repairs (if there are bouncy spots in your floors in more than one place), replacing the plywood as well as the roof shingles and the trim around the edges of the roof, replacing cabinets in the bathroom and kitchen as well as the fixtures, and adding, demolishing or moving walls inside your home, multiply the number of square feet in your building by $50 - $75 per square foot.
   
   
4. If you are renovating a 100+ year old, three or four story, historic landmark property that has not been well maintained for about 20 - 30 years, multiply the total number of square feet of enclosed floor space by $100 - $150 (maybe $200) per square foot.
   
   
5. If you are putting an addition on your building, you must use new construction costs. For this exercise, assume $200 per square foot of new, enclosed space, for a residential property that is less than 50 years old.

Make a note of your quick cost estimate here: $____________.

You can verify the $/sf values in your area by calling the Home Builders' Association or a few good general contractors and setting the parameters we’ve used above.

I can tell you that the numbers above are nowhere near construction costs in New York City, but they might not be too far off for Cleveland, St. Louis, and other small cities and their suburbs.

MORE INFORMATION

You’ll find lots more information about the home remodeling process in Managing a Renovation: Staying in Charge and Out of Trouble, our friendly and comprehensive homeowner’s guide to remodeling project management. Download the table of contents and a sample chapter, or go to the order form to purchase it.

We offer ready-to-use construction forms, including a complete remodeling contract, in our Bookstore, as well. Have a look.

And, you may want to look at our list of More Resources for some great design ideas.

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