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Re: Unreinforced foundation walls

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John,
I think the Ont Bldg Code recognizes the inherent
weakness of unreinforced hollow block relative to
concrete, i.e.workmanship, etc.  Also, the OBC does
not require the masonry to be filled solid which I think
is a major error.  Those failed basements I have
seen, were all block with the horizontal crack at
or near mid-height--0ne exception was an old concrete
basement with near horizontal cracks in two of four
walls.  It was on a hill with higher fill than allowed
and the concrete may have been questionable--owner not
wanting to pay for testing.
Gary

On 2 Feb 2005 at 9:42, John Riley wrote:

> Don et al,
>      What Stan wrote is true, i.e., calculations indicate that most
>      basement
> walls do not withstand lateral soil pressures without vertical
> reinforcing. What Don says is also true ? in Ontario, the prescriptive
> part of the code for houses and small buildings allows up to 8'-0"
> basement walls without reinforcing, provided that the soil height does
> not exceed 7'-7", for an 8" concrete wall, or 6'-0" for a 10" block
> wall.
>      Many thousands of homes have been built with unreinforced
>      concreted and
> masonry basement walls.  However, my experience has been that some of
> the masonry block walls do not stand up under certain conditions,
> e.g., poor soil, water pressure, vehicle loading.  Consequently, I
> never approve masonry walls for basements.  Besides, they trap water
> in unfilled cells and leak.  
>      I am also careful about long walls and gable end walls in
>      concrete with
> little vertical load.
> Gary
> -----------------
> Gary,
>      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
> 
> PS:  Shouldn't the 10" HCMU retain higher backfill than the 8"?       
> 
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