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Re: Repairing Cracked Masonry

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Rand:

You have piqued my curiosity.  Are the 1" cracks vertical (this seems to
have been assumed by some but your original post was not clear)?  If so,
how high do they go?  Is the 1" crack width uniform through the depth of
the brick masonry?  How often are the cracks occuring?  Do you have an
idea of when they open up vs. when they close (i.e. seasonal, daily, etc)?

Basically, I am wondering what is causing them.  As at least one other
person had suggested (James Cohen), it would be prudent to figure out what
is causing the movement before attempting a repair on the cracks.  In your
response to James, you seem to already be aware of this and have an idea
what is causing the movement in the cracks.  Now, however, I am
curious...are you willing to share what you think is causing the cracks to
move?

I think that James' point is still well worth noting...if you know what is
causing the movement and "cure" that, then fixing the crack should be much
easier.  If the movement issues are solved, then the previously attempted
fix of caulking the crack should work (might still require a backer rod).
IF the movement issues cannot be "cured" then it is likely that there will
be no repair option that will work well.

Regards,

Scott
Adrian, MI


On Tue, 9 Nov 2004, Rand Holtham, P.E. wrote:

> Stan,
>
> It looks like that's what they've used previously. These are large cracks
> say 1" wide. The rebar will not fully restrain movement, it is after all
> just a 1/4" rod but hopefully would add ductility to the joint and hopefully
> restrian the movent that disloges the caulk. Yes there is a lot of hope in
> that sentence. Point well taken though.
>
> Harold,
>
> I have my doubts too, that's why I posted... what do you mean develop a
> mortar doesn't an epoxy mortar already exist?
>
> David,
>
> The Engineer who evaluated the problem 15 yrs ago had the same conclusion as
> you did. But he neglected to notice the 4 to 5" of differential movement in
> the foundation and that there is no discrete lateral force resisting system.
> Differential foundation movement alone can cause a variety of  crack shapes
> vert, horiz, stairstep then add the displacement from wind loading.
>
> Now set me straight on the expanding brick...As the brick expands it creates
> a 1" gap??? I thought you leave a 1" gap so the material can expand into
> that gap without causing distress....(I'm with you that clay expands and
> concrete shrinks over time but...)
>
>
> Keep it coming this is productive, Thanks guys :>
>
> Rand
>
>
>
> ----- Original Message -----
> From: "David Fisher" <dfisher(--nospam--at)fpse.com>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Tuesday, November 09, 2004 12:15 PM
> Subject: RE: Repairing Cracked Masonry
>
>
> > Sounds like "Mother Nature" has created a control joint where none
> > previously existed...
> >
> > Is that true?
> >
> > What, if anything, did the architect specify?
> >
> >
> >
> > Since it's vertical and not stepped, it would appear to be the result of
> > thermal/moisture stresses and not structural issues...
> >
> >
> > As we know, clay expands when wet while Portland cement products (CMU)
> > Shrink over time.
> >
> >
> > If it's a naturally occurring control joint, its probably needed in
> > exactly
> > or
> > Nearly that spot.
> >
> >
> > Treat it as such: fill the gap with a compressible filler and backer
> > rod/seal the
> > Exterior side of the joint.
> >
> >
> >
> > David L. Fisher SE PE
> > Fisher + partners
> > 372 West Ontario
> > Chicago 60610
> >
> > 312.573.1701
> > 312.573.1726 fax
> >
> > 312.622.0409 mobile
> >
> > www.fpse.com
> >
> > -----Original Message-----
> > From: Rand Holtham, P.E. [mailto:rand(--nospam--at)sigmaengineers.com]
> > Sent: Tuesday, November 09, 2004 11:49 AM
> > To: seaint(--nospam--at)seaint.org
> > Subject: Repairing Cracked Masonry
> >
> > Lister,
> >
> > For the sake of brevity I will condense a very complex problem into a
> > simple
> >
> > question that I have no answer for:
> > I have a large crack (actually many large cracks) in the brick veneer on
> > an
> > eight story building. This crack allows water to penetrate the building
> > and
> > attempts to caulk have been unsuccessful as the crack moves thereby
> > dislodging the caulk. I am contemplating the addition of a small  (say #2)
> > rebar in the grout joint  (grind out joint repoint with epoxy mortar or
> > other?) so that the reinforcing crosses the crack in essence stitching the
> > crack together. Then applying the caulk with the idea that the added
> > reinforcing will control the crack from movement beyond that which the
> > caulk
> >
> > can tolerate. I can see extending the reinforcing 24" or 36" on each side
> > of
> >
> > the crack This is not to stop the building movement but to facilitate
> > waterproofing the brick facing.
> >
> > My simple question is--- will the rebar bond well enough to the brick and
> > mortar for this to be effective? Any thoughts will be greatly appreciated
> > ~:-).
> >
> >
> > Rand
> >
> >
> >
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