Demolition hammers are the tools of choice for busting up large areas of concrete. The biggest of these tools, called breaker hammers by manufacturers, are typically referred to as jackhammers. There are three common types of jackhammers you can rent: electric, gas and pneumatic. An electric jackhammer that plugs into a 120-volt power source is the type you'll rent for most DIY projects. These tools exert 40 to 60 pounds of force and typically cost about $90 for a one-day rental (cost varies depending on rental-center rates; see SOURCES in PDF below to find a rental center). For smaller jobs or work that requires more precision, consider a smaller demolition hammer ($75 a day; see "Chipping Hammers," in PDF below).
Contrary to its tough-guy image, a jackhammer is not tough to operate. The weight of the tool and its mechanical action do the work. Improvements in vibration dampening have made most models relatively easy to handle. Transporting and lifting the tool into position is often the biggest challenge. Most rental centers provide a specially designed two-wheel cart that makes it much easier to roll the tool and bits to the job site.
You'll probably have to contend with embedded rebar and reinforcement wire inside the slab. For dealing with these hidden challenges, a few tools worth having on hand are large wire or cable cutters and an angle grinder with a cutting wheel or a reciprocating saw with a metal-cutting blade. A large pry bar is handy for shifting and loosening large pieces. And a wheelbarrow will save you trips when it's time to haul debris.
A day with a demolition hammer is no picnic, but it sure beats using a sledgehammer. Remember to let the tool do the work. Break the slab into small pieces you can lift. It's easier to make more trips hauling small pieces than it is to make fewer trips with bigger, heavier pieces.
Demolition is exhausting, but it's also one of the most satisfying phases of any project. The results of your effort might not be pretty, but they'll serve as a not-so-subtle reminder that you're well on your way to completing an exciting construction project.
A demolition hammer isn't a difficult tool to use. Here are the basic keys to success:
- Maintain a balanced stance.
- Keep the tool balanced in a vertical position.
- Don't lean on the tool; let its weight do the work.
- When removing an entire slab, start breaking with the bit positioned 6 to 12 in. from the edge of the slab.
- Make a series of holes about 6 to 8 in. apart until crack lines develop.
- Stop hammering and carefully tilt the demolition hammer and bit to pry chunks loose.
- When removing only a center area within a slab, start breaking in the middle of the area to be removed. Work toward the perimeter, and use a chisel bit to break along the perimeter line.
- Continue to create cracks and break up the slab until it is in pieces that are small enough to carry.
Not every job requires a full-size jackhammer. Smaller demolition hammers, often called chipping hammers, are a better choice for work that requires more precision or when you need to use the hammer in a horizontal position, such as when removing floor tiles. Smaller demolition hammers exert 5 to 30 pounds of force, depending on the size of the tool, and they typically weigh less than half as much as a full-size tool.
Bits for Breaking
The jackhammer bit you select depends on the job. A point bit is designed to break the initial holes and get cracks started. Chisel bits break up large pieces and make more controlled breaks along a line. Wide chisels are most effective when used close to the slab edge. Wide chisels are also used to scrape material off of a surface and to loosen soil. Spade bits are specifically designed to break up compacted soil.