Q: I just read your article on removing a fireplace and chimney. My wife and I are planning to do this ourselves, as we rarely use the fireplace in our home.
How should I calculate the cost of the project, which includes replacing the wall and roof repair?
A: The cost of plugging the hole occupied by your fireplace is made up of two parts: labor and materials. And because you’re not adding high-end finishes such as cabinets, appliances or countertops, the lion’s share of the cost will go to labor.
If you and your wife do it yourselves, the cost of labor goes away. That’s the sweat in sweat equity.
There will be costs in addition to labor and materials if you contract the job, such as permits, and the contractor may also bill for overhead costs, which will substantially increase the price.
Because you and your wife are demolishing the fireplace, you might as well finish the job. The only tasks you might want to contract are replacing the siding, especially if it’s stucco, and the roof.
Once the fireplace is gone, there will be holes in the floor, the outside wall, the ceiling and the roof. Estimate the cost of materials for each component of the building.
1. The floor
Remove the fireplace bricks until they top out below the floor joists, which will be either 16 or 24 inches apart. When replacing the hole where the fireplace was with new lumber, continue with this spacing. Make sure to double up the joists on the edges of the hole. This will give you an edge on which to nail the new subfloor. Use steel brackets, called joist hangers, for added strength.
Figure the total number of linear feet of the joists, multiply this by the cost per foot and that will be the cost of this component. For example, if you require 14 feet of 2-by-8s costing $1.25 per foot, the cost for the floor joist component is $17.50 plus tax.
Use the same process to figure out the cost of the subfloor. Make sure the material you use (plywood or oriented strand board) is the same thickness as the existing subfloor material. Buy full sheets, each measuring 32 square feet, and cut them to fit. Last time we checked, 3/4-inch OSB cost around $12.50 per sheet.
2. The wall
To patch the wall, you will need to replace the wall components. From the inside out, they include drywall, framing, insulation, sheathing and either stucco or wood siding. Figure the material for each component separately. Drywall should cost about $6 per sheet, 2-by-4 studs around $2 apiece, OSB sheeting $10-$15 per sheet. Cost of the insulation and siding varies depending on the material. You may want to leave stucco siding to a pro. As always, go with a contractor who is licensed, bonded and insured. …CONTINUED
Framing the wall may be a bit tricky because the new wall must be tied into the existing wall. Modern framed walls are constructed with double top plates. The second top plate strengthens a joint where two walls meet. Metal strapping can substitute if the local building code allows.
3. The roof
Use the existing roof, rafters, soffits and sheeting as a template to measure how much new material you need. Roofing is called out by the "square," which is 100 square feet. The cost of asphalt roofing is about $60-$70 per square.
By now, although each job is unique, it should be pretty clear that the cost of materials is going to be relatively small. When you’re pricing out the job at the lumber store, add 15 percent for items you may have forgotten. That should be pretty close to what it will take to put the house back together.
As we’ve said before, simple frame construction is not rocket science. If you have the will to do it, you can save yourself a pretty penny. That should be pretty close to what it will take to put the house back together.
We’ve given you a method to estimate costs, but our list is not exhaustive. For example, we didn’t mention drywall mud, nails or paint. You may also need to buy a specialty tool or two. Miscellaneous items will add to the total cost, but nothing that should break the budget.
There are many books with information on the components of a wood-frame house. One of our favorites is "How to Design, Build, Remodel & Maintain Your Home" (Fireside, 1995) by Joseph D. Falcone.
Finally, don’t forget to get a building permit. You will be required to submit at least a rudimentary framing plan for approval. The plan checker and the building inspector can point out any errors or omissions. Building inspectors are a wealth of information, and in our experience they are more than happy to share.
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