We just installed three patios and a set of stairs connected to our
current patio. My husband noticed they did not install expansion
strips. He questioned it, and this is their reply. My question: are
they telling us truth, or trying to avoid rework?
"In reference to the concrete, we did dowel into the concrete as
However we did not provide expansion strips due to the fact the point
of an expansion strip is to allow the concrete to remain free standing
from the foundation. Therefore by doweling into the foundation, this
would defeat the purpose of providing an expansion joint.
Consequently the expansion joint would only create an eye sore to the
patio and more importantly provide a point of entry for water, which
in our experience has created problems. Expansion joints have allowed
water to enter beneath the concrete and in between the foundation,
which after a season in Colorado of freezing and thawing will
inevitably cause problems. It is our policy not to use expansion
strips due the problems we've experienced after using them. Also, the
only concrete typically inspected in a county are areas for structural
Considering their detailed explanation they gave you it hardly matters
what the facts are. They are not coming back to put in any expansion
joints regardless of anyone may say. I'm not expert in this field but
the sidwalks I have seen all have expansion cracks. No concrete
sidewalk last forever and all of them eventually have some type of
cracks whether or not they are doweled and whether or not they have
Art, you and Lawrence both seem to be thinking of the joints that
allow concrete to crack due to shrinkage. These can be tooled in the
surface or saw cut. The OP is talking about the expansion felt or
foam that you would put along a building, retaining wall, or other
slab that you would want the new concrete to move independently of.
Two totally different things.
Without seeing your job it is hard to know where you might need expansion
joints but it might be a good idea not to have them next to the house but
that doesn't mean you shouldn't have them. Also concrete passes water
pretty readily even without a joint.
The reason for using expansion joint(s) is to give the concrete a
place to expand when it is trapped and when the pavement sections
get long and need relief to grow in summer heat. A sidewalk
trapped between the foundation and the driveway, between two
buildings, between the garage and the street are all examples of
places that need expansion joint, they are also placed about every
60 feet in sidewalks and paving. Expansion joints are installed
before the concrete is poured, they are not typically something to
install after the fact, and the results would likely not be
Contraction joints are sawed or tooled to T/4 depth.and designed
to give the concrete a controlled place at which to crack.
Concrete will crack and should not ever exceed 12' in any one
direction without a contraction joint. Re-entrant corners require
joint relief as do substantial dimension changes.
It sounds to me that you had a fairly professional crew pour your
concrete and I don't disagree with anything they said. I do
assume you have sufficient contraction joints, I assume your
patio(s) touch grass on 2 or more sides so the concrete is not
trapped. I assume you have sufficient grade, 1/4" per foot, to
get water off the slab and away from the house.
Keep the whole world singing . . . .
DanG (remove the sevens)
A lot of that depends on where you are located and the conditions
you are likely to encounter.
E.g., water migrating under there can lead to frost heave in the winter
time (if you experience significant cold in Winter)
Why would you *not* want to undertake this? As a lazy solution,
you might be able to try silicone (sp?) caulk -- but, you'll
use a boatload of it!
[If you go that route, consider rolling up (loosely) some news paper and
jamming it in the slot to fill up some of the void so you don't end up
pumping "gallons" of caulk into a slot that extends down several inches, etc.]
As an aside, note that this slot is an excellent way to get cables (e.g.,
landscape lighting, irrigation, etc.) across a driveway without having to
use a water drill to bore *under* the slab! Sort of like wedging speaker
cables, phone lines along the edge of wall-to-wall carpeting inside your
My husband says they are used as a buffer between garage floor and drive when
they are poured. Would you explain to him now that they have deteriorated when
can happen to the concrete drive and garage floor?
Concrete can expand/contract with temperature. We frequently see sidewalks
"buckled" here -- not from roots or anything beneath but, rather, from
the cumulative effects of prolonged heat and undersized/missing
Water can also infiltrate under the slab and heave (when frozen) during
the cold months.
You can fill the joints with a caulking compound, buy more "felt"
or other products designed for "expansion joints". It's hard to guess
what problems would befall you without knowing what sort of
conditions you are likely to face.
With most of these things, if it's there, it's there for a *reason*!
I live in Ohio and have had the harshest winters these past two years. If he
doesn't fill the void between the drive and the garage floors, is it likely that
water will undermine both and cause heaving of the concrete?
I am in colder Alberta, every house we had built had rebars connecting
garage floor and driveway. Expansion strip was always there. If garage
floor and driveway bed is well prepared there won't be any problem. If
the concrete work was shoddy all kinda problem will occur. Common
mistake is laying the rebars flat on the bottom of slab.
It should be imbedded in slab.
Probably not. Most driveways are poured over a foundation of gravel
to facilitate drainage. The risk is that water will *sit* just under
the concrete and, being that close to the surface, will freeze and
lift the concrete (water expands as it freezes).
Here, for example, our frost line is relatively shallow. It is
unusual for us to experience many cold days/nights so the ground
never has a chance to "freeze" -- to any depth.
As a result, many roads are poorly built -- sitting virtually
atop the "dirt" beneath (no drainage). The inevitable cracks in
the roadway allow water to get beneath it. If we have a particularly
cold winter (or, several consecutive cold days) the water is close
enough to the surface that the roadway (asphalt) is ruptured
by the expansion beneath.
These additional cracks lead to more water infiltration... more
heave... more cracks, etc.
Is there some reason you/your hubby don't want to fix the problem?
It's not a huge undertaking, doesn't require special tools or
knowledge -- just time and a little money.
If he's objecting to any work towards this, ask him what he *thinks*
the role of the felt strip may have been... why did the builder bother
to put it there? If it is just a *spacer*, why didn't he use a piece
of wood? Or, pack dirt into that area? etc.
As DanG explained the proper use of expansion joints this was a proper
install for your application. It sounds like they did a good job, heck
you are extra lucky they even knew to dowel in..and why.... there are
so many guys that think since they have a truck and a bucket of
finishing tools that they are concrete contractors. Seriously you were
lucky be happy with the results and recommend these guys thats what
keeps us good guys one step ahead of the rest.
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