Getting To The Heart Of Structural Flaws:
The ad read, "Handy Man Special, minor
structural repairs probable." I had long wanted
to tackle a "fixer-upper." I had faith in my
basic skills and felt this would be a good way
to earn equity in a house . But I was worried.
How could I tell if the place was structurally
sound? Well, I bought the house and fixed it,
too. Along the way I found out how to tell if a
house is sound.
Here is my recommended "10 minute EKG" for
evaluating the foundation of any house you are
considering for purchase. You won't become an
expert on structural soundness, but it can help
you avoid a lemon and know when to seek
professional advice.
You'll need a strong flashlight and some basic
understanding.
The foundation is the masonry that supports the
house. Built into the ground, it supports the
weight of the house and keeps the dirt out of
your basement. Movement of any part of the
masonry usually spells trouble and can be
detected by cracks in the walls of the
foundation. You can read some meaning into those
cracks.
The foundation usually consists of two parts:
the footing and the walls. The footing is a
concrete pad about eight inches deep and usually
16 to 24 inches wide. The footing supports the
walls, which may be masonry block or poured
concrete. The deeper the basement, the thicker
the walls must be to resist the pressure of the
outside earth. (The concrete slab on the floor
of most houses is not a structural component and
almost always has some hairline cracks, which
are usually caused by shrinkage. These can be
safely ignored.) However, never ignore large or
multiple cracks in any surface.
To begin your inspection, start in a basement
corner and look down the wall surfaces. Make
sure the walls are straight (in a flat plane,
perpendicular to the floor and ceiling.) Inward
bulges in the wall may mean the earth is shoving
in and are signs of big trouble. Back off from
the wall, walk alongside it, and examine it from
top to bottom. Cracks or cracks that have been
previously repaired should get close attention.
Scan every wall and note what is outside each
wall.
It is important to distinguish between the
normal cracks found in foundations and those
that indicate structural trouble. Don't worry
about the house's early settlement (initial
movement that usually occurs within the first
two years of a house's construction) or very old
cracks. Be more concerned with continuous
movement, not onetime movement.
Diagonal cracks starting in the corners and
progressively widening as they rise from the
floor are very common. They often step along
mortar joints in a roughly diagonal direction
and often occur within the first two years of
construction. The early movement and resulting
hairline cracks usually occur because the
footings are unevenly loaded and frequently rest
in soils of somewhat differing bearing
capacities. (Bearing capacity is the ability to
support weight without sinking or compressing.)
Small hairline cracks like these are usually
safely ignored.
Watch out when you spot the following
conditions:
A diagonal crack that exhibits signs of recent
movement especially if it occurs after initial
settlement.
A large crack. (If your finger can fit in it, it
is large.)
A long horizontal crack on an outside wall.
A vertical crack on any wall.
A slant or bulge on any wall.
Cracks large enough to admit your little finger
are significant and are best examined by someone
with experience. Other signs of recent movement
are a crack that was filled with mortar and has
reopened; or a crack in a recently painted wall
with no paint within the crack.
A very common crack is a long horizontal one
significant above the slab height. These cracks
frequently occur a foot or two below the outside
soil surface in a masonry block foundation and
are often caused by water that has collected
against the masonry, frozen, and then exerted
inward pressure.
This usually occurs because the gutters and
downspouts have failed to deliver runoff water
far enough away from the foundation. Repairing
the gutters and spouts and increasing the grade
(the slope of the soil away from the house)
ordinarily will be sufficient to deal with the
problem. But if the crack is more than 1/8 inch
wide, "pinning" may be necessary. Pinning
consists of inserting bars into the cores of the
blocks and grouting (filling with concrete)
around the bars. This greatly increases the
tensile strength of the wall and often isn't
very expensive.
Other common horizontal cracks can occur high up
on a basement wall on the inside of the
foundation wall where it touches the garage
slab, that is the concrete that the car rests on
in the driveway. When a garage slab (or any
outside slab) settles, it can push the
foundation wall. But as long as water isn't
running down the driveway and getting under the
slab there is probably no cause for concern. The
force of tree roots can also produce large
horizontal cracks and bulges. Remove the root
and pin the wall as noted above.
Vertical cracks are usually found at the
midpoint of walls; they can be uniform in width,
or, more commonly, can progressively widen as
the crack rises from the floor. This usually
means that the corners of that wall of the house
are still settling. This is cause for concern.
Houses that are still settling usually call for
"underpinning," a method of enlarging existing
footings to better enable them to handle the
weight they support. Houses resting over
expansive soils may even require piers under
their footings to transfer their weight to
stable soil. These cures tend to be expensive
and call for a professional evaluation.
Almost all structural problems are related to
moisture in the soil. If movement is suspected
in a house, poor drainage is the likely culprit.
So it is particularly important that drainage
around homes be maintained. Houses on hillsides
with deep basements sometimes get bulges in the
uphill foundation wall. This is often due to
poor drainage; the resulting saturated soil
increases pressure against the wall. The wall
could collapse.
If the gutter downspouts of a house empty at the
corners of the house they can frequently
saturate the soil, which lessens its bearing
capacity. Improving the drainage to eliminate
saturation is often sufficient to arrest ongoing
movement.
As a final step in your house's EKG, look for
settlement in the area around columns or metal
post bases (the supports for interior beams).
Circular cracks in the slab around posts or
columns are bad signs and usually indicate that
underpinning is required.
That's it. Ten minutes. Do this to every house
you see. If you don't find any of these symptoms
the chances are extremely good that the house
rests on a sound foundation.