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Home > Archive > Building and Construction > March 2006 > slab crack new house
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slab crack new house
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| drowetx@yahoo.com 2006-03-16, 12:21 am |
| The concrete slab of my new house has a hairline crack just behind
where it is supported by a 5' high cinder block retaining wall (with
brick facing). This crack is parallel to that retaining wall and
follows it for much of its length, making it apparent that the wall has
settled into the ground more than the dirt beneath the rest of the
house.
I know that slabs crack, but this one concerns me. The builder also
sees a relationship between the crack and the location of the retaining
wall, but says that the slab will not separate because of the embedded
rebar.
FWIW, I hadn't noticed this crack until just after temporary 8' 2x4
studs supporting the roof structure were replaced by permanent 6x6
beams (also placed on the slab above the retaining wall).
What do you think ? What shall I do ?
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| drowetx@yahoo.com wrote:
> The concrete slab of my new house has a hairline crack just behind
> where it is supported by a 5' high cinder block retaining wall (with
> brick facing). This crack is parallel to that retaining wall and
> follows it for much of its length, making it apparent that the wall has
> settled into the ground more than the dirt beneath the rest of the
> house.
>
> I know that slabs crack, but this one concerns me. The builder also
> sees a relationship between the crack and the location of the retaining
> wall, but says that the slab will not separate because of the embedded
> rebar.
>
> FWIW, I hadn't noticed this crack until just after temporary 8' 2x4
> studs supporting the roof structure were replaced by permanent 6x6
> beams (also placed on the slab above the retaining wall).
>
> What do you think ? What shall I do ?
>
that slab certainly can tear away. It all depends on size placement ant
number of rebars involved. It cracked from inadequate soil compaction
under the wall. Most house builders throw a few number 3 or 4's flat on
the ground and call that good. My house I'd tell them to bring in a
hoe-ram and tear it all out and do it the right way. Read your
contract. you may be screwed. good luck
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| deviL doG 2006-03-16, 9:21 am |
|
<drowetx@yahoo.com> wrote in message
news:1142479100.80XXXX.325200@v46g2000cwv.googlegroups.com...
> The concrete slab of my new house has a hairline crack just behind
> where it is supported by a 5' high cinder block retaining wall (with
> brick facing). This crack is parallel to that retaining wall and
> follows it for much of its length, making it apparent that the wall has
> settled into the ground more than the dirt beneath the rest of the
> house.
>
> I know that slabs crack, but this one concerns me. The builder also
> sees a relationship between the crack and the location of the retaining
> wall, but says that the slab will not separate because of the embedded
> rebar.
>
> FWIW, I hadn't noticed this crack until just after temporary 8' 2x4
> studs supporting the roof structure were replaced by permanent 6x6
> beams (also placed on the slab above the retaining wall).
>
> What do you think ? What shall I do ?
>
You should test to see if the slab is indeed settling.
Take a long straight edge (a very straight 8' 2x4 will do) and place it
perpendicular to the crack, with the crack at the mid-point, standing tall
(1.5" side on the floor). If the 2x4 rocks (like a see-saw) then there is a
grade change and possible settling. Try the other side of the 2x4 (the other
1.5" side) and try it in 4 or 5 locations, one test is not conclusive and
"straight enough" is not straight. No rocking: no settling. Now it is most
likely a shrinkage crack which is a very common, non-structural issue. If it
is a shrinkage crack then my guess would be that there is a footing strip,
column pads, or some other sub-slab structure in that location. That would
cause the concrete to cure at a different rate than in the rest of the slab
and accelerates the shrinkage. Shrinkage crack begin to appear around day 21
of the curing process which may coincidentally coincide with the stage of
the framing.
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| Al Bundy 2006-03-16, 11:21 pm |
| drowetx@yahoo.com wrote in news:1142479100.80XXXX.325200
@v46g2000cwv.googlegroups.com:
> The concrete slab of my new house has a hairline crack just behind
> where it is supported by a 5' high cinder block retaining wall (with
> brick facing). This crack is parallel to that retaining wall and
> follows it for much of its length, making it apparent that the wall has
> settled into the ground more than the dirt beneath the rest of the
> house.
>
> I know that slabs crack, but this one concerns me. The builder also
> sees a relationship between the crack and the location of the retaining
> wall, but says that the slab will not separate because of the embedded
> rebar.
>
> FWIW, I hadn't noticed this crack until just after temporary 8' 2x4
> studs supporting the roof structure were replaced by permanent 6x6
> beams (also placed on the slab above the retaining wall).
>
> What do you think ? What shall I do ?
>
Well, think about later...much later...when you are selling the house.
What will the buyer think of it? You don't get to opportunity to say "Oh,
it's ok! Honest Injun! Really".
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