My
first house, which was built in 1950, had a set of outdoor
concrete stairs to a small porch. When I built an addition to the
house I changed the location of the back door and I demolished the
concrete porch. Once I removed the top slab, it was simple (fun,
actually) to bust up the remaining porch, which was made from
cement blocks.
The normal approach to making
foundations and stairs is to pour them separately. But I think
I've seen pictures in books where people have made them in one
pour.
My first approach would be to
give the porch a few good whacks with an 8-pound sledge hammer
(wear safety glasses!) to see if it breaks up. Hit the sides near
a corner. If the sides were made from cement blocks, they will
break easily. The top may be a concrete slab, which will be harder
to break.
The trick to breaking up concrete
slabs is to render them "unsupported" and hit them in
the middle of their span. A concrete slab without reinforcement
cannot span more than a few inches. A sidewalk, for example, can
be easily broken by lifting one end with a crow-bar, putting a
rock under the raised end, and hitting the middle with a sledge
hammer. If your porch has a concrete top, it may be supported by
sand underneath. If so, that sand can be removed so the slab has
no support in the middle, rendering it vulnerable to a hammer
blow.
You can rent a jack-hammer, but
for a similar amount of money you can buy a 7-inch dry-cut diamond
blade (about $50) for a circular saw. These blades last about 100
times as long as those $3 fiber-grit masonry-cutting blades.
I highly doubt you could damage a
poured concrete foundation, even with one of those huge
commercial-duty jack-hammers (unless you deliberately tried to).
As you will only be giving a glancing blow to the house
foundation, all you are likely to do is make a few small chips in
that concrete. There is a very good chance that what appears to be
well-connected is really just attached with mortar, or just weakly
bonded concrete.
Even a basketball-sized chunk
blasted from the house foundation could be patched with concrete
patching material.
The worst case is the steps were
made from the same pour as the foundation. (That will be evident
when you clobber the porch with a sledge hammer... if the step
material doesn't break away readily, they're well-connected. But
if there is sand under the steps, I'll bet the whole thing is made
from cement blocks.) In the worst-case scenario, you can cut the
concrete with a saw, (which will only cut about 2-1/2" deep)
and then break it up with a sledge hammer. Just use the saw as a
means of making a "control joint" which is a weak line
where the concrete will break when struck with a sledge hammer.
You won't be able to make a cut
right against the house, so you may have a 2 or 3 inch thick
remnant of porch protruding from the house. This could be removed
by making successive cuts in the face, (like a grid pattern) and
then chipping it away with a cold chisel.
SAFETY WARNING:
When hammering on concrete you
absolutely positively MUST wear safety goggles. Those
high-velocity chips of concrete can render you blind in a
millisecond. Also, if you use a diamond saw for cutting concrete,
you should wear hearing protection (as well as safety glasses),
because the noise is very loud. A dust mask is a good idea also,
unless there is a good breeze to carry away the dust.
If you decide to hire somebody, a
carpenter with a little remodeling experience should be able to
demolish the steps.
An Example:
 |
The
old concrete steps were no longer needed because I closed up
the old entrance. |
| Nearing
completion of the project, the location of the old steps was
visible where the concrete paint ended. The masonry steps
were attached to the basement foundation with only a little
mortar and paint. |
 |
Tools For Concrete Demolition:
- A large (8 pound) sledge
hammer.
- A cold chisel and a small
sledge hammer, at least a 32 ounce sledge, to drive the
chisel.
- A 7-inch diamond blade for a
circular saw.
- I recently bought a 4-inch
diamond blade ($40) for an angle grinder. This tool is useful
for making shallow plunge cuts in concrete, and for cutting
ceramic tile.
- A hammer drill with a carbide
masonry bit is a useful tool. This can be used to drill a
series of holes to weaken the concrete, which can then be
broken with a sledge hammer. But this approach is tedious.
Bruce W. Maki, Editor.
