Hello, I will build a concrete block wall 4 blocks high for a garage. Three
of the courses will be below grade. I want to make this wall as strong as
practically possible. (I could not use a poured wall because of access
problems). I live in a freeze/thaw area. I want to use some rebar in the
cores for strength. Should these cores with rebar be filled with concrete
or mortar? Also anything I can do to prevent cracking from the freeze/thaw
cycles? Would a control joint on each wall make sense? Thanks, paul
Not sure what you are trying to accomplish. What do you mean by
"freeze thaw"? Obviously, you need to be below the frost depth in
your area or no amount of rebar will save you.
If you are concerned about lateral force, then core fill with
concrete. A bond beam would help, though it's hard to see why it
would be necessary on three courses. I assume you are filling the
center and prepping for a slab---in that case the slab and fill would
prevent the wall from pushing in.
No need for control joints.
The block will need a concrete footing below frost line wide
enough to carry the dead and live loads imposed based on the
bearing capacity of the soil. Vertical steel in concrete filled
block cells at 4' on center and at each side of any openings
should be adequate for your needs. A 16" wide by 8" deep footing
with at least 2 #5 bars horizontal should be adequate for the
Keep the whole world singing . . . .
Basically I don't want the wall to crack. It will sit on a 8 x 16 footer at
the frost line. The wall will be 4 blocks high with 3 below ground. My
concern was could expansion/contraction from freezing/thawing crack the
wall? And if so, is there anything I can do to prevent this?
I'm not sure this would normally happen, so maybe it's not a problem, but
since I don't know I sent the post. I will use the rebar in the footer and
at 4' as DanG suggested.
Well, that's pretty interesting considering who's saying it. You're
an old timer and you often point out about the benefits of old time
construction. They didn't use rebar in footings for generations, so
what's happened to the soil recently that it's now required in every
situation? Right, nothing.
Code is an attempt to create a one-size-fits-all building. If a
builder knows what they're doing, and take into account local
conditions and compensates for them, there is no need for rebar. If
Code calls for it, well, you have no choice and you have to put it
in. That doesn't mean that the rebar actually adds any benefit and it
does not compensate for poor foundation practices.
Most don't use rebar in driveways either but I want
#4, 24" ew just because I like my driveway to stay
Code around here calls for 2 #4 in footings, so just
habit I suppose.
Yeah, I go back to where we used 18" stone basement
foundations directly on the ground with no footings.
I'll take steel to stop the cracking they did.
Cheapest thing for what they do in the whole
I just did a quick check on frost line depth in Indiana, and depending
on where you are, it can vary from 30" to 42". The first thing you
should do is verify the frost line design criteria.
The buried portion of the foundation does not usually have a big
problem with freeze/thaw. If you're garage is unheated and there's
soil on both sides of the foundation, there's almost no chance of a
only becomes an issue if there is a fair amount of water in the soil.
While you are excavating your foundation, you should determine what
sort of soil you have and it's drainage capabilities. If there are
any doubts, you can put in drainage tile (not actually tile, it's
really pipe) around the perimeter, and/or use gravel and sand in the
Rebar in footings is unnecessary unless you have doubts about your
soil or if your subgrade preparations are faulty. A couple pieces of
rebar won't make the footing act like a beam, it will just keep the
pieces together, and, frankly, it's extremely rare for different
sections of a footing/foundation to have any appreciable differential
settlement unless the soil conditions and drainage are poor, or your
subgrade preparations are faulty.
I guess you catch my drift by this point. If you don't take into
account the soil conditions, drainage and subgrade preparations, any
work you do after that will be at risk. 'Superior' construction won't
negate those failures.
The two #5 bars continuous proper laps and corner bars are code
required minimum here. Perhaps the OP is not in a code compliance
situation, but I would put it in as a minimum. Engineer designed
would be higher.
Keep the whole world singing . . . .
I may have missed it but has anyone suggests a "permit" might be
required for this job? In my area, I can go to the local city hall and
ASK for the proper depths and construction practice that is
acceptable. The inspector who will come out to look and see if your
footings are in fact deep enough generally will give a homeowner
guidance short ort of taking responsibility but will tell you what he
expects to see in order to sigh off on the job.
I cannot see where a permanent building like this would not require
one. Pretty hard to hide it if you want to forgo a permit but if you
want to do it w/o permit, you can still ask the "what if I wanted to
do, such and such"?
They would give some info better than the guessing game you are
playing. The fellas giving you advice are going from experience and
most likely know their job well but they won't be there to help you
correct it if the local building inspector makes you do it. Big job,
make sure you do it right the first time.
Roscoe aka Rick
Knowledge is like money, the less you talk about it
the more people assume you have.
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