Cinder Block Repair

What is the best product to use to permanently repair these cracks in my chimney block?? Seems there is a lot of options/products when researching this and I’ve got no experience….Thanks.

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Mortar, and seal it all up somehow or moisture will continue to get in and cause more damage.

There are mortar repair products in a caulking tube. That would be the cleanest method rather than using a trowel and tuckpoint tool.
I’d look at the top of that chimney. That type of cracking could be from water getting in from above,freeze/thaw. The chimney block in your photo look like they have some large open pores. Concrete block is not waterproof, it can soak up some water. Seal the top, fill the cracks and then apply a clear penetrating sealer to the chimney walls where the cracks are.

If it were mine I’d probably completely wrap it in a metal lath to give it some structure since it looks to be splitting pretty good. Then spread a couple coats of mortar over that. Make sure the top is sealed and has a good slope to shed water.

Could even have it stucco’d or rock veneered if looks are important.

Quikrete has a bunch of products that would work but as guys have mentioned it looks like your missing a top cap on the blocks and that’s what is letting moisture into the blocks and cracking them. I’d go out on a limb and guess it’s only going to get worse if it’s not fixed the right away. Top cap, fill the crack, and cover the exterior again.

Do your self a favor and demo those block and lay up new ones with a actual cap. Easy and cheap.

Bearcat89 wrote:

Do your self a favor and demo those block and lay up new ones with a actual cap. Easy and cheap.

X2

A guy should be able to carefully take those block Off and put new on over the clay liner, if the clay liner is cracked also your gonna wanna put a stainless steel liner inside the clay. Had to do this on one of our fireplace chimneys this fall, not terribly expensive, and is done right and safe!

Bearcat89 wrote:

Do your self a favor and demo those block and lay up new ones with a actual cap. Easy and cheap.

X 3 check the clay chimney that may already be getting soft and cracking as well. I had the same situation on my garage. The clay chimney actually collapsed inside the cinder block. Another option might be to get rid of it all together and go with regular gas or wood chimney that’s metal and flashing on the roof.

Bearcat89 wrote:

Do your self a favor and demo those block and lay up new ones with a actual cap. Easy and cheap. [/quote

X4 Patching will buy you a couple years before it cracks again, and you have to start all over again.

New chimney time. Pay attention the footing. IMO it all started at the bottom.