Tuckpointing at Base of Foundation Question

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Old 11-08-14, 09:07 AM
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Tuckpointing at Base of Foundation Question

Hello All,

I've really appreciated the responses that I got from my last question so I thought I'd pose another question to the master builders here.

I'm redoing a lot of tuckpointing on my garage and have an old sidewalk that runs along two walls of it. I was considering creating a little 'slope' that would bridge the gap from the lowest brick to the sidewalk. I've attached a first image of the foundation itself and 2nd with a rough drawing of what I was trying to say in words aboveName:  2014-11-05 22.22.13.jpg
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Would this be a good idea to keep water from seeping in between the crack or will it just flex too easily away from the sidewalk?
 
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Old 11-08-14, 02:45 PM
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You've neglected to mention what material your "little slope" will be made of. And exactly how you plan to attach it to the building and sidewalk.
 
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Old 11-08-14, 06:47 PM
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Bridgeman,

Good point. I've been using type N mortar for all the tuck pointing as my garage is fairly old. The house was built in 1916, but I have a feeling the garage was afterwards at some point. Not positive. I assumed that type N mortar would work for this purpose as well.

As for how I planned to attach it, I was going to coat both the sidewalk and first brick with a concrete bonding adhesive like this: SikaLatex 1-Gal. Concrete Bonding Adhesive and Acrylic Fortifier-187782 at The Home Depot. I'm not sure if this works for brick/mortar or only concrete...

Would it be worthwhile to sink some screws into the brick and sidewalk for a mechanical adhesion as well?

Thanks again!
 
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Old 11-08-14, 08:16 PM
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It would be a mistake to try to bridge a moving opening with any type of rigid mortar. It will first begin to crack, then eventually break out in chunks, large and small. Which will put you back to where you are now, after going through the effort of removing the material that's still bonded.

A far simpler solution would be to thoroughly clean the joint opening, then place some tight-fitting backer rod in the entire joint (about 3/4" below grade), and then run a heavy bead of self-leveling, industrial-grade polyurethane in the opening. Once cured, the stuff will last just about forever, and easily flexes as the sidewalk moves while the building doesn't.
 
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Old 11-09-14, 10:37 PM
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Well much appreciated Bridgeman. I took your advice.

I guess what I learned from the experience is to ALWAYS try to jam a backer rod in the opening even if you think the opening is tiny. Uses so much less polyurethane this way.
 
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Old 11-10-14, 05:52 AM
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backer rod serves only to give the material proper shape factor ( depth:width ratio ) which then allows its cohesion & adhesion properties to work as designed for most jnt sealants, 3/8" is max sealant depth
 
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Old 11-10-14, 11:55 AM
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Actually, backer rod serves other functions as well. In addition to preventing use of excess sealant material, the most critical function for proper sealant performance is that it prevents 3-sided adhesion, which normally causes sealant failure. Correctly-applied sealant should only bond to the 2 sides of an opening being sealed, not the bottom.
 
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Old 11-11-14, 05:51 AM
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isn't that shape factor ? bdge's right - shape factor & prevention of 3-side adhesion is critical to sealant performance
 
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Old 11-11-14, 12:00 PM
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"Shape factor" has nothing to do with whether something adheres to something else. Joint sealants will always fail (by separation and tearing down the middle) if backer rod consisted of material that enabled sealants to stick to it, resulting in adhesion along the bottom in addition to both sides of the joint.
 
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Old 11-13-14, 05:26 AM
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shape factor influences or often determines cohesion while clean sidewalls promote adhesion,,, backer rod ( closed OR open cell ) neither provides nor enables adhesion on the btm of the installed sealant,,, know you know this, bdge, but others may appreciate,,, obviously 3sided adhesion is the enemy of sealant performance
 
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Old 11-14-14, 10:26 AM
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Sorry, but you are wrong. As I stated earlier, and as most of us learned in Joint Sealing 101, shape factor has nothing to do with preventing adhesion along the bottom of a joint. The physical and chemical characteristics of the material that makes up the backer rod are what prevent sealant from sticking to it, not the fact that it's semi-circular in shape.
 
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