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Re: Unreinforced foundation walls - Fix?

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Several have recommended fixing the larger size cracks.  I am curious as to what type of system and material you recommend for the fix (i.e. a solid type grout or a flexible mastic?).  Since the cores are hollow it would seem that only a surface/cosmetic type "fix" is possible.

Thomas Hunt, S.E.
ABS Consulting



"Jordan Truesdell, PE" <seaint(--nospam--at)truesdellengineering.com>

02/02/2005 08:36 AM

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Re: Unreinforced foundation walls





At 09:42 AM 2/2/2005 -0600, you wrote:
>I've seen plenty of non-reinforced HCMU basement walls in Iowa and
>Illinois and virtually all of them have a chest-high crack, some opened more
>than others.  Realtors used to call me for a report on "sale-pending"
>basement wall cracks, but they finally figured out I always say repair is
>necessary; and they quit calling.
>      Another troubling thing about non-reinforced HCMU basement walls is
>that the first course was/is often not a full mortar bed.  The result is
>that if water appears on the basement floor in the northeast corner it may
>be entering the wall at the southwest corner, no way to know.
>      My rule is (and this may have come from a code or something else I
>read) all below-grade HCMU should be fully grouted, all cells.  I can live
>with that.
>John P. Riley


Show me an unreinforced HCMU basement wall, and I'll show you a crack.  I
won't design them, but I see them in real estate transactions regularly.
Instead of failing every one of them (most are 30 to 50 years old), I
usually let anything less than 3/16" go with a warning to verify grading
and drainage, and to monitor the crack on a regular basis. Bigger, and
we're looking at a fix.

What I've found more interesting is that the crack usually occurs one to
three courses _above_ the mid-height.  It's worth noting, as it means that
the wall is not in a pinned-pinned condition, as usually assumed in design
texts, but is fixed-pinned. Fixed-pinned has the maximum moment  occur at
(no surprise) about 0.55H above the fixed end.  If i were fixed-fixed (the
sill & floor) or pinned-pinned, you should be seeing the tension crack
about 1/3 or 2/5 from the bottom of he wall.  But now I'm just rambling....

Jordan



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