Soils in the Hope, Kan., area where I live and work are tough
on foundations. While the expansive clay soils aren't as bad as
in some parts of the country, they still cause bulges and
cracks in many foundations. In the 35-plus years I've been a
contractor, I've worked on more than a dozen of these damaged
foundations. Every job is different, so we use several
techniques, depending on the situation.
One of the most effective methods I know is to tie a bulging
wall to a mass of reinforced concrete outside the foundation.
Rods are run through the foundation wall and embedded in some
form of concrete deadman placed below the frost line and
outside the building. The deadman's weight and surface area
work like a boat anchor to counteract the pressure exerted by
the heavy soil. When we don't have room for the deadman method,
we sometimes pour a new heavily reinforced wall inside the
existing foundation. Both methods work and have advantages. On
one recent job, we used both.
On one section of the house, the original foundation
— poured without any steel and weakened by age
— had bowed about 2 inches toward the inside. I
decided to repair and reinforce this area with the deadman
method. The plan was to connect the bulging foundation to a new
porch footing with steel rods. The weight of the new porch
foundation would provide plenty of extra mass to resist the
A second section of the foundation lacked anything as heavy as
a porch foundation to connect to, but it did have a convenient
window for getting concrete inside. In that section, we decided
to pour a heavily reinforced wall inside the existing
foundation for additional strength.
To make sure that both plans were workable and that the
existing foundation was otherwise suitable for supporting a
two-story house, we consulted with an engineer and arranged a
site visit. After getting the engineer's approval, we started
Getting Down to Demolition
The first section of foundation was below an existing concrete
porch. I was concerned that removing the existing porch slab
would damage the house or siding as the pieces were broken up.
To prevent damage, we used a gas-powered cutoff saw with a
diamond blade to cut the slab close to the house (see Figure
Figure 1.Cutting the existing porch slab prevented
the concrete pieces from seesawing and damaging the siding. The
crew used a leaf blower to remove dust and make it easier to
see the blade and cut line.
Once most of the pieces had been broken up and hauled away, we
removed the smaller pieces, using a little more finesse than
the improvised ram attached to my subcontractor's backhoe
Figure 2.To avoid the risk of running a jackhammer
on an elevated slab, the excavation sub used an improvised ram
to break up the concrete. When the slab and foundation were
gone, the smaller pieces close to the house were removed with a
When the porch was gone, I had the excavator scrape away the
soil from the damaged foundation and trench below the frost
line for the new porch footing. I wanted to keep the bearing
capacity of the soil, so we were careful not to over-dig.
Using a rotary hammer, we drilled through the foundation wall
in four spots, about 7 feet on-center. I inserted lengths of
3/4-inch threaded rod and bolted them to 30-inch pieces of
heavy-duty steel channel. The channel would act like a huge
washer, and the threaded rod would make it easy to bring the
assembly under tension once the footings and foundation were in
place (Figure 3). With the threaded rod running through the
wall to the exterior, I had a local welder attach it to lengths
of hot-rolled steel that were hooked around the rebar,
reinforcing the new porch footing.
Porch Footings Do Double Duty as
Figure 3.Like a giant plate washer, steel
C-channel (left) placed across the existing foundation's weak
area spreads the resisting force from the concrete deadman
outside. Threaded rod passing through the foundation wall
(center) is welded to steel rods that hook around the rebar in
the deadman (right).