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Re: Unreinforced foundation walls & pilasters

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Jeff,

Good testimony from a seasoned vet...  The few
foundation inspections I do are because something has
failed and in each case - surprise - they were not
built in accordance with the prescriptive code.  I try
to limit my scope to reiterating the condition and
stating preliminary concepts on how to rectify the
problem.

In this area, a lot of builders add pilasters instead
of reinforcing the blocks.  At the risk of writing
this without having my IRC in front of me, I don't
recall that it covers that condition at all.  How can
builders be building these with inspector approval? 
Are the NCMA masonry Tek design guides for pilaster
walls an acceptable prescriptive design for
residential use?

Jim Wilson, PE
Stroudsburg, PA

--- Jeffrey Fertich <civilben1968(--nospam--at)hotmail.com> wrote:

> Again I will say that you, my engineering brothers,
> mainly commerial 
> engineers will have to get over doing the
> engineering on unreinfoced block 
> and concrete walls.  As I am fond of saying "Don't
> take my word for it, 
> let's look at the code." I have looked at hundreds
> of these cracked walls 
> and everytime the wall is undersized per the code
> charts., any codes.  The 
> charts work when applied. I still deal with
> engineers and contractors that 
> think horizontal reinforcing will help, it does
> nothing.   I will agree that 
> there is a little voodoo when it comes to the
> connection between the plates 
> and joists, but i have never seen a wall that
> follows the charts fail.
> 
> Jeff Fertich, PE
> Gettysburg, PA
> 
> >From: "Gary Hodgson & Associates"
> <ghodgson(--nospam--at)vaxxine.com>
> >Reply-To: <seaint(--nospam--at)seaint.org>
> >To: <seaint(--nospam--at)seaint.org>
> >Subject: Re: Unreinforced foundation walls
> >Date: Thu, 03 Feb 2005 07:55:29 -0500
> >
> >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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> > >
> > >
> > >
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