SIGforum
Repairing cracks in cinder block mortar.
May 09, 2022, 12:49 PM
Skins2881Repairing cracks in cinder block mortar.
Should I use mortar or the caulk style stuff to fix this?
Jesse
Sic Semper Tyrannis May 09, 2022, 12:53 PM
RogueJSKDo you want to do it the easy way, or do it the right way?
The easy way to do it is to patch it with some masonry caulking. This doesn't do much for the structural integrity, and it can sometimes be hard to match the color, thus making the repaired area stand out cosmetically.
The right way to do it, to both make it look better and repair its structural integrity, is to scrape/chisel/grind out the outer inch or so of the cracked mortar areas and reapply mortar to these joints. This is called tuck-pointing or repointing.
And if you haven't already, you'll want to try to determine why it cracked. Some cracking from settling can be normal, but it can also be the hallmark of a bigger foundation issue.
May 09, 2022, 01:27 PM
Skins2881Additional information, I'm painting, so matching won't matter as much as final looks after paint.
Jesse
Sic Semper Tyrannis May 09, 2022, 01:37 PM
h2oysFor some reason I can't zoom in on your pic. What I am looking for is to see if they are just hairline cracks or if the cinder blocks have pulled away from the mortar joint.
As long as you don't have a structural issue, or if there is not water infiltration if your pic is inside your basement, you could get away with caulking.
If structural or if water is a problem, grind out to a depth at least 1" and follow the crack lines joints as a guide. Mix up a batch of mortar, make the grind line wet, and press in the new mortar.
Then you use a joining tool to make the mortar smooth to match the surrounding joints. Use a small sprayer and spray the finished joint a few times a day (the longer you keep the joint moist the "harder" the mortar becomes). Wait a few days and then paint.
May 09, 2022, 02:10 PM
Skins2881Sorry for bad pics. The cracks are small, they look larger from the paint failing on top of the cracking.
Jesse
Sic Semper Tyrannis May 09, 2022, 02:22 PM
h2oysNo problem...I bet if I was logged in using my phone I could have zoomed in but I am at work on my desktop computer.
That type of cracking is considered normal and routine. I don't see signs for bad settling. Hence you could just scrap off the old paint around the crack, seal with caulk, and repaint.
May 09, 2022, 02:43 PM
RogueJSKIf you're going the caulk route, ensure that the caulk you choose is paintable.
May 09, 2022, 03:54 PM
Skins2881Bought the caulk, don't think it's going to work. Says 3/8" max gap. Some are almost half inch, if not over 1/2".
Here's what I'm looking at cleaned out.
Jesse
Sic Semper Tyrannis May 09, 2022, 04:19 PM
RogueJSKRepointing is not difficult or all that challenging. It's just more effort than squeezing out some caulk. Lots of Youtube videos on how to do it.
The most time-intensive part is chiseling out all the cracked mortar. It can go faster if you have access to an angle grinder with a diamond blade.
May 09, 2022, 04:25 PM
Hamden106Has one end of your structure settled?
SIGnature
NRA Benefactor CMP Pistol Distinguished
May 09, 2022, 08:32 PM
GA GatorIf there is occupied space on the opposite side of this wall, have it ground out and patched by a mason. The threat of mold is real.
If this is a garage or non conditioned space use Sika Mortar fix. Go to there website and read the product data.
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May 09, 2022, 09:44 PM
Skins2881quote:
Originally posted by GA Gator:
If there is occupied space on the opposite side of this wall, have it ground out and patched by a mason. The threat of mold is real.
If this is a garage or non conditioned space use Sika Mortar fix. Go to there website and read the product data.
Wait, what? Have all of it ground out? I removed all the areas that had any cracks. There would be no benefit to removing mortar everywhere. Just want it to look decent after paint. Given the condition of block currently it will never be perfect. I just want it to look good for 5-10 years.
I have looked at the Sika product you mentioned. For now I am going to buy that or similar so that the contractor can pressure wash to remove the bulk of failed paint/cracks without intrusion through the poor mortar joints. Then will reevaluate how to deal with the rest of the failing paint/cracks.
I really want to if not for cost just parget it and cover the original crappy workmanship.
Jesse
Sic Semper Tyrannis May 10, 2022, 06:17 AM
h2oysGiven your goals, just use the specialized caulk and paint thereafter
May 10, 2022, 08:57 AM
Captain MorganBuy one bag Type S mortar and a bag of brown sand. Do not get yellow sand. Buy a round jointer.
Hose out the joints you made.
Mix 2 parts sand and one part Type S. Add water for a almost stiff consistency. The joints need to be damp then using a trowel pack in the mortar with the round jointer.
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Benjamin Franklin May 10, 2022, 09:53 AM
smschulzCaulk like Big Stretch will work but I would use mortar.
It will look much better, IMO.