We have an outdoor porch that is sitting on a slab (i believe). The one side of it has a pretty substantial crack and I'm wondering the best way to fix. Should i just get some masonry caulk and a backer rod, or should i get some mixture? I believe that they are just concrete bricks that are settling apart and/or water water hydraulicing. At it's largest the crack is about an 1/2 inch in height. The depth seems almost infinite at some points but is at least 2 inches. Here are some pictures for reference.








(16 inch ruler)

Advice, pertinent articles, or best googling terms greatly appreciated.

Thanks for reading.

 

The crack looks uniform enough, with the exposed corners rounded, to indicate it's a moving construction joint. A (tooled) bead of polyurethane, over recessed backer rod, should seal things up adequately.

 

Okay. If i understand correctly I will shove a backer rod in there, use some caulk (guy at the hardware store recommend this DAP® Concrete Waterproof Filler and Sealant), then smooth it over with finger/tool (aka tooled).

May I ask what a "moving construction joint" is, my quick Googling didn't bring up much (or i just don't know what to look for).

UPDATE:
You're probably saying i should use something like this: DAP® Premium Polyurethane Concrete & Masonry Sealant, because it's polyurethane.

 

The hardware guy's recommendation is water soluble while still flexible, meaning it's not a true polyurethane. The second product you linked should be better performing and longer lasting, but since it's been years since I've bought or specified any such products, someone else might come along with a more current recommendation. And to answer your question, a moving construction joint is a joint intentionally placed during the construction sequence of a structure, for the purpose of allowing movement (expansion/contraction) to take place.

Note: Hardware store salesmen can usually read product labels, and know what they sell a lot of, but don't usually possess a lot of product performance knowledge. You might do better by going to a masonry supply place, where they make a living by selling to professionals.

 

we'd use basf/sonneborn's NP 1 as posted in the other forum - best wishes !