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Re: Repairing Cracked Masonry

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You may have to use more than one mortar in your application. You may have to use a more fluid mortar to bond to the rebar and masonry, and confine it with a backer rod. You will then have to remove the backer rod and use a mortar matching the existing mortar in color and texture. On the exterior mortars, I like to develop a matching mortars. I don't know how old your building is, but a matching mortar is better than one that contrast.

When I say "develop". You will have to work with a masonry contractor and try to mix mortars of various consistencies to get the performance you want.

One other thing that you need to bear in mind is that brick masonry mortar will expand AND contract depending on the temperature and humidity. You also need to be aware that creating a hard spot in a wall (using a type S mortar in some areas in a field of N mortar) can cause the fracturing of the face shells.

Harold Sprague

From: "Rand Holtham, P.E." <rand(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: <seaint(--nospam--at)>
Subject: Re: Repairing Cracked Masonry
Date: Tue, 9 Nov 2004 12:50:46 -0600


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.


I have my doubts too, that's why I posted... what do you mean develop a mortar doesn't an epoxy mortar already exist?


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 :>


----- Original Message ----- From: "David Fisher" <dfisher(--nospam--at)>
To: <seaint(--nospam--at)>
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
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

312.573.1726 fax

312.622.0409 mobile

-----Original Message-----
From: Rand Holtham, P.E. [mailto:rand(--nospam--at)]
Sent: Tuesday, November 09, 2004 11:49 AM
To: seaint(--nospam--at)
Subject: Repairing Cracked Masonry


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


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