Foundation repair can be the most expensive repair
that you will make to a property. One of the saddest things I’ve heard in the
investment community are the stories of investors who have purchased a property,
rehabbed it, and put it on the market only to have the buyer’s inspector tell
them there was a problem with the foundation. Foundations can be very expensive
to repair, and repairing them after the house has already been fixed up and
painted can mean redoing a lot of sheetrock and paint work. All of this means
money out of the investor’s pocket, and if the expense goes deep enough, it just
might wipe out your profit.
Part of my mission on this planet is to help keep the investor’s money in his or
her pocket. It comes under the heading of “Comforting the disturbed and
disturbing the comfortable” in my charter. That’s why we are going to learn
how an investor stays out of trouble when a house has a foundation problem. We
are going to talk about what the foundation does, what causes problems with it,
how to tell those problems, and how they go about fixing them. This is the
lecture portion of the foundation training. To get the required lab, you’ll have
to go with me on an inspection. I will show you all about it and soon you will
be able to make the evaluation of the foundation with a certainty born of
knowledge and experience. Sounds good, huh? Let’s get started.
The foundation of a house, whether it is a concrete slab (slab on grade) or a
block and beam (pier and beam) foundation has a job. The job is to keep the
house level and stabile. When the foundation moves up or down or side to side,
then the platform that the house is sitting on enters a state of failure. It is
failing to perform the function for which it was intended. What this means is
that everything that was depending on the foundation for support is now in
jeopardy, because the support is no longer there. It is like one of your legs
suddenly becoming 2” shorter than the other one … it has consequences for the
way you stand and the way you walk.
When the foundation is no longer doing its job, there are certain tell tale
signs that appear. Here’s what to look for when you are checking out the house
before you buy. On the outside, look for cracks in the brick veneer. These
cracks may be stair-step, vertical, or horizontal. There may be cracks in the
grade beam (the part of the concrete slab that you can see at grass level), and
there may be a separation between the doors or windows and the siding that comes
up against those doors and windows. The cracks next to the doors and windows
will look like a long skinny pie slice with one end open wider than the other,
or it may look like. Stand at one corner of the house and look along the mortar
lines or the lines of the horizontal siding. If there is a deflection (a rising
or falling of the foundation) then you will most likely be able to pick it out
here.
On the inside, look for cracks radiating diagonally from the doors and windows
in any direction. Look at the tops of the doors, do they have that little pie
slice between the top of the door and the door jamb? Do the doors open, close
and latch properly or do they stick? Are the windows operating the way they
should or are they jammed? Now look at the floors. If there is hardwood flooring
and the foundation has moved, you will see little cracks open up between the
sides of the boards where they abut one another, and you may also see where the
boards have separated end to end due to the stress of the foundation moving.
Now get out your 4’ level and go from room to room. Put the level on the floor
near the outside wall of the room at right angles to the wall. There is a bubble
in a little glass vial in the middle of the level, and on either side of this
vial is a line. The bubble has to be exactly in the middle of these two lines
for the level to be sitting level. If you have to lift up one end of the level
to get the bubble to go between these two lines on the vial, then you have
deflection. Deflection means the floor is not level and foundation has probably
shifted. The distance between the floor (carpet, tile vinyl) and the bottom of
the level is the amount of deflection in 4’. The allowable deflection is ¼” in
4’. If you have to lift the end of the level up ¼” or more, then you need top
have the foundation looked at by a licensed structural engineer or a reputable
foundation contractor.
Once you have checked the floor with the level at right angles to the outside
wall of the room, turn it to be parallel with the wall. In other words, you have
checked the foundation from left to right, now test it from front to back. Go
from room to room and check all the floors. You can also put the level on top of
the door trim and on the window sills to check for level as well. Again, the
maximum allowable deflection is ¼” in 4’ before you need repairs.
We know about the doors and windows and sheetrock cracks, but is there anything
else that happens to a foundation? Yes. There can be damage to sewer lines that
run under the foundation, they can become separated or broken, and then you have
to dig them up to fix them. That gets expensive. Gas lines are forbidden to be
placed under concrete slabs, but some people put them there anyway because they
think that it is more convenient for them. If a gas line gets ruptured under a
slab it turns into a very expensive mess to repair. The other thing we see is
that water lines, especially the line that comes into the house from the water
main, gets pulled apart when the slab gets raises again.
What I have told you about checking out foundations by looking for separations
and checking the floors also holds true for block and beam foundations as well.
Block and beam and pier and beam are the same for purposes of this discussion,
they both mean that the house is up off the ground. The main difference between
pier and beam and slab on grade is that the pier and beam house will move more
than the slab house. That means that the front door sticks when the weather gets
dry for awhile, and then it will work just fine again three days after the rain
comes back.
What causes all of this hopping around of the foundations? Clay, mostly, black
gumbo clay. The type of clay that we have in the majority of the subsoil; in
this part of the country is a nasty black material. It is hygroscopic, which
means that if there is water in the soil surrounding the clay, then the clay
will attract and absorb the moisture. When it does this, the clay expands like a
sponge. When it expands, it increases in volume and lifts everything that is
sitting on top of it. When the moisture level of the soil surrounding the clay
drops, as in a drought, then the moisture will migrate out of the clay into the
surrounding soil to be evaporated back into the atmosphere.
So now you know what to look for when you’re looking at a foundation, and why it
does the things it does. In the next post I’ll tell you about the different ways
to fix foundations, both slab and pier and beam, and how you can prevent this
from happening to your own home or your rental properties.
Last post we talked about why foundations fail and what happens
to the house when they do. We talked about why it is important to fix them
from an investment point of view, and how to tell if the foundation is going
to need work.
How to tell a bad slab from a good one, what you need to know about pier and
beam foundations. Important stuff, my friends, these repairs can easily run to
several thousands of dollars. If you have provided for that in your repair
estimate before you buy the property, then you are in good shape. If you do
not find out that the slab has to be repaired until after you have taken the
property, then the foundation repair is going to come out of your refrigerator
as you watch your profit margin swirl down the drain.
When you decide to repair a foundation, the first thing you do is make a
diagram of what need to come back up. This is done by evaluating the
foundation with a spirit level (a bubble level), or with a Compu-level, which
is a computerized piece of equipment that has a base station and a long cord
with a sensor/sender unit. The base station sits in the middle of the house,
and the sender/sensor unit. The operator takes the sensor unit around to the
different parts of the house and he gets a reading as to whether that
particular part of the foundation is higher or lower than the base unit. From
this he is able to determine what has to be raised and how much. He makes his
diagram and then the leveling begins. This is all true whether the foundation
is slab or pier and beam.
The basic repair for slab foundations is to dig holes under the slab at the
edge of the foundation, and install concrete columns under the slab that are
strong enough to support the weight of the foundation they will support. These
columns are of two kinds: drilled piers, and driven piers. Drilled piers start
as a hole that is dug into the ground to depth of about 12 feet. Steel
reinforcing bar cages are placed in the hole, and concrete is poured in to
fill the hole to about 18” from the bottom of the slab.
These drilled piers, also known as bell bottom piers because of the
under-reaming at the base of the excavation, must then sit for a week to ten
days for the concrete to cure hard enough to proceed with the next step. When
the concrete is cured, then the crew comes back to the house and places jacks
on the top of the concrete and literally jacks the house up until it is level.
The foundation is then blocked up in the level position, and the holes are
back filled.
Some engineers prefer the steel reinforced bell bottom piers because they are
not subject to lateral movement (side to side in the hole), and will not allow
for the deflection that is sometimes experienced with driven piers when the
pilings hit a rock and begin to go off at an angle. On the other hand, just as
many engineers like the driven piers because they are faster and easier.
Let’s look at the other most common method of slab repair. The other type of
pier is called driven pilings. Driven pilings are concrete cylinders about 6 –
7” in diameter and about 13” tall. You start this repair by digging a hole at
the edge of the foundation. This hole will go under the edge and by about 24”
deep under the slab, with a seat at the outside for the worker to sit on while
he drives the piers. It looks like a hole with a shelf at 12” and a place to
put your feet that goes to 24”.
When all of these holes are dug under the foundation the workers will begin to
push the concrete cylinders into the ground under the edge of the slab with a
100-ton hydraulic jack. They push one cylinder down to into the earth as far
as it will go, when they relieve the pressure on the jack and put another
cylinder on top of the one they just pushed into the ground, and begin to push
them into the ground one after another until the slab begins to raise up from
the jacking.
This raising up is called the “point of refusal”, and means that the column of
concrete cylinders has reached the point where the sub-soil refuses to accept
further penetration. At this point a large concrete block called a capstone is
placed on top of the cylinder column, and the pier is ready for the final
leveling.
When all the columns have been driven to the point of refusal, then the
jacking begins. With either kind of pier, driven or bell-bottom, the jacking
part must be done all at once. That means that the whole side of the house
must be jacked at the same time or the slab will crack like a sugar cookie as
the wave of stress passes along the line of piers while it is jacked one pier
at a time.
Typical jacking involves having one man in each hole with a hand hydraulic
jack and a jacking foreman supervising the whole operation. The jacking
foreman tells the men in the holes how many times to pump the jacks. The place
where the foundation has settled the deepest may get 15 pumps on the jacks to
start with, and the ones on either side where the foundation is not as
effected may require only 100 or 5 pumps to start. The process of jacking
continues with the jacking foreman checking inside and out with a large level
or a Compu-level until the house is completely level. At this point cement
blocks and steel shims are placed at the top of the capstone to support the
foundation, the jacks are released and removed, and the holes are backfilled.
Pier and beam houses are a lot simpler. First of all, pier and beam houses are
houses that sit up on blocks. Pier and beam is the name commonly applied to
this type of foundation in much the same way as soft drinks are commonly
referred to by the name Coke. Pier and beam means that piers were put into the
ground before the house was built and masonry blocks were placed on top of
them to form the foundation to build the house on. Some houses have this
system, most have a block and base system, which is a block of cement about
20” square and 4” thick that has concrete blocks or brocks built up on top of
it. Either way, the sills (4” X 6” timbers or beams) are put on top of the
blocks, and floor joists on top of these. Next comes a layer of ship lap or
plywood that covers all of this structural material, and that forms the
sub-floor of the house. This sub-floor is what we nail wood floors to, or put
padding and carpet or vinyl over. With the slab foundation we just put
flooring over the concrete.
The process of leveling pier and beam foundations also begins with a map of
what needs to be done, and how much you are going to lift the foundation at
each point on the map. Wood blocks and hydraulic jacks are used to jack the
sills back into position, nd again they are blocked into place using treated
wood and metal shims.
Pier and beam foundations are much easier to repair because they are more
accessible and do not require holes to be dug in order to do the work. Costs
for pier and beam repair normally run from several hundred dollars to about
$2,500 for the whole job. Driven piers run anywhere from $140 on up to $350
per pier for exterior piers, with interior piers being about another $75 each
to break out the interior concrete floor and repair it when the work is
finished.
Which kind of piers do I like? I [prefer the driven pilings because they can
be done in one to two days start to finish. Drilled piers (bell bottom piers)
take longer to dig, and have to sit for ten days to cure before the jacking
can begin. Most investors I know of use the driven piers.
If you have questions about foundations call me, or catch me at a meeting.
I’ll be happy to help. If you need an answer right away, you can call me and I
will tell you what to do. I’m Kevin Smith, and I’ll see you out on the
property.
Kevin Smith
Forward Assist Inspections
(713)858-1330
Texas Real Estate License #3234