stucco cracks

~1980 house is built of stucco over cinder block (in some places) and slump block (in others).
There are long, narrow, noticeable cracks in the exterior stucco suggesting some subsidence (water is all ground sourced, here). Neighbors suggest "just slather some paint over it". <frown>
Is it OK to just patch these cracks? Or, should we expose the underlying blocks to get an idea as to how much they've penetrated the structural block?
If *just* superficial, any advantage to polymeric patches vs. (cement) "stucco patch"?
And, if the cracks permeate the underlying block (presumably on mortar lines), what's the recommended remedy? Anything "injectable"? (fine mortar, cement adhesive, etc.)
Thx!
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Don Y wrote:

Since the cracks are there because of movement, I would not use a cementatious material to patch them. I want something that allows for a bit of movement. I caulk and paint them. For hairline up to maybe 1/8 I use acrylic caulk, I had a joint between a free standing wall and the house that had opened up to 1/4 - 1/2, used polyurethane caulk.
The norm IME for stucco cracks is on block joint lines, easily visible. I haven't worried about whether the cracks penetrate into the block joints as there is nothing I could do to repair same without major effort and expense and I view some joint cracks rather the same way as I would in wood; i.e., minor local damage does not impair the whole.
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[apologies, this thread slipped out of my display "window" -- out of sight...]
On 10/3/2015 2:45 AM, dadiOH wrote:

Why? What do you see as the downside? If the building is still "settling", wouldn't any new mortar lines open themselves under the continued strain?
I.e., how would such a repair differ from the way it *was*? Or, the way the rest of the joints that *haven't slipped?

So, you only deal with the cosmetic aspect of the stucco (surface) and don't sweat any structural consequences?

We have a similar issue with a wall that adjoins the house and supports the back/side gate. The closing of the gate inevitably causes the wall to "move" wrt the house, opening a large crack. I plan on sinking some bolts into the house and tying the wall to them. Then, fill with mortar.

Yes. Very apparent (for masonry homes). Stucco on wood frame seems to generate arbitrary cracks -- typically more vertical than running along horizontal mortar lines as with block.

I was considering opening the stucco and seeing if there was a substance that could be "squirted" into any cracks in the mortar lines. Then, repairing the stucco (house is due to be painted, hence the reason for addressing it now)
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Don Y wrote:

********************** That's why I don't use cementatious material...it cracks. Caulk stretches to a point; if it later stretches to the point of breaking, THEN I would worry about WHY things were moving and - possibly - comsider methods of prevernting it.
Concrete/mortar just doesn't like any movement. My house is block on slab. The slab did its cracking long ago, settled down after it did. I don't recall any stucco cracks on the house walls save one lanai that has two end walls that are stucco over ply over studs; there were a few hairline cracks early on, caulked almost 20 years ago, still good.
There is a knee wall around a courtyard; it developed some cracks following joint lines, a playing card size piece of stucco sloughed off too. All were repaired with polyurethane caulk maybe five years afo, all are good.
A hose bib in the courtyard on a house wall started leaking inside the wall maybe 8-10 years ago. After cutting out the stucco and block around it, the problem turned out to be a nipple that had rusted out at the threads. After replacing the nipple, the cavity was filled with foam up to about 1/4" from the outside wall. I the used thinset to stucco the remaining 1/4". Still good.
I have a seven foot high wall around a garden off the master bedroom. I didn't have it stuccoed when I built the house, got tired of looking at the joints so I used thinset to stucco the 30' of wall. I notice it has developed cracks on the block joints in an area about 2' x 3' and will push some caulk into the cracks someday soon.
**********************

I don't understand what you are asking.
**********************

********************** For the cracks I am talking about - hairline to maybe 1/8" - I can't foresee any structural consequences.
**********************

********************** I think that would be a mistake unless the footer and block for the wall were tied into those for the house when built. If not, and if you tie them together, movement in one will affect the other. If they are separate, the norm is a "cold" joint...one that allows for independent movement.
**********************

IME, the cracks are as likely to go on vertical block joints as horizontal; usually, both.

********************** Well, I guess you could run some epoxy in but what good would it do? If there is movement again either it would fail or new cracks would open up elsewhere.
Keep in mind that block walls are very strong in compression but quite weak in shear; very easy to push down a block wall. Also, a tiny, almost imperceptible bit of movement can open a crack farther away that is many times the size of the movement. Rather like a lever and a fulcrum...move the long part of the fulcrum and that movement is amplified at the short end.
I'm not saying that cracks are a good thing, just that they are pretty much inevitable, depending on the geology of the area. My house is sitting on sand, 60' to rock. Stuff moves here - especially newly built stuff - and I don't consider a few stucco cracks to be a structural worry. YMMV :)
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On 10/5/2015 10:31 AM, dadiOH wrote:

Again, so what? It gives way -- it doesn't force the adjoining *blocks* to crack. I.e., worst case, I end up with a similar crack in a similar location at some time in the future. Or, if the settling has stopped, no crack.

But caulk just "plug the holes" (gaps) it has no structural value. A thick layer of paint would similarly "hide" the cracks -- and do little else.

Ditto.

The largest/most noticeable of these is located above any load bearing points. OTOH, there are others that appear from stress/strain.

We had a similar problem on the back wall. I removed the galv nipple and fitting into which it was fastened and replumbed with copper and brass from there out (I now have a good understanding of what doctors must deal with when doing laproscopic surgery! :-/ OTOH, I suspect they aren't trying to sweat joints 6 inches inside a masonary wall through a 3 inch opening!). A bit of mortar and a scruff finish leaves the spot indistinguishable from the original stucco that I removed to access the plumbing.

Cosmetics don't worry me (much). Paint covers many sins. I am more concerned with the structural consequences leading up to the cracks and subsequent (as water infiltration and inevitable freezing expansion work to further weaken those areas).

I.e., replacing the failed mortar with more mortar is no worse than it was *before* the cracks developed, right?

OK.

The separation is a result of the ~16" wide stack of cinderblock supported *solely* at the footer being "slammed" by the spring loaded gate wanting to close against it forcefully. The pile of blocks is much more willing to "move" than the house against which it abuts.
A similar gate that is not springloaded has no evidence of this sort of problem (the problem gate wants to be spring loaded to ensure it remains closed even if not latched -- so pets can't escape; the other gate has no "pet access")

Yes. But on WOOD FRAME, there are no vertical block joints. So, instead of a vertical crack terminating (or "turning") at the next course of blocks, it continues to propagate downward following whatever stress line the underlying construction yields.
It's not uncommon to see fairly new (stucco over wood) homes a year later with long veins of caulk appied to try to "fix" the cracks that have developed in that first year or so.

If there is going to be movement, then there is nothing I *can* do -- the house has enough mass to have "a mind of its own". OTOH, if it has settled into this configuration, then bridging the cracks with something structurally sound adds strength to the wall (instead of just covering up a blemish)

Our problem is from groundwater pumping. Gradual subsidance. Nothing that can be done to reverse it. No way to know if/when it will stop. Nor any way to know that it *hasn't* stopped, already!
If its going to continue, then anything I do is going to be undone by "mother nature". But, unlikely to cause BIGGER problems. OTOH, if it has stopped, then anything I do is a permanent fix going forward.
(should I, instead, wait 10 more years and see if the cracks have become larger? :> )
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and

Stucco on the north wall here at the old Haney place is bubbling up. Not all over - just enough to spend a half day. I scraped off a few of them and patched them OK -- does the job, but doesn't exactly match the texture. Original pattern was swirls in the first layer and then the usual throw on and smooth out the 2nd layer.
Looks like this only the first layer on mine has a dragged brush texture.
http://www.myphotoshopsite.com/tutorials/level_5/images/stucco_orig.jpg
Stucco with these 3D patterns is a stupid idea if you ask me, but the lovely miseries Snuffy likes it. So... it was either hire a swirler or learn myself. It collects dirt on the rough surface, and water hang on it. It's not a good idea to wash this stuff off as I found out, so there no real easy way to keep it clean. I like stucco in general - it has been over 20 years and most of the walls are still like new. But I would never do the fancy 3D look again.
I watched a few youtube videos and then experiemented with various make shift tools. I found that using the brush piece of a push broom gives a pretty close match. So I've got the swirling down pat. Still can't figure out how to throw the 2nd coat up on the wall without scooping it up in my hands. I guess the hand-scooping will have to do.
Also mixing color is a waste of time for me. I got the stucco color where the sample matched exactly in the store and mixed a small batch using a 5 pound package scale. I figured it would be off, but it turned out to be like night and day. Got the exact mix. Then added the exact amount of water. When it dried is was so far off the original color that I figured I would just use plain stucco and then paint the whole wall. Add another day on the ladder....
I knew it would be a hard job, but, man, this is worse than digging a ditch. Stucco artists are definitely "artists." They deserve every nickel they get for this kind of work. Unfortunately my nickel supply is low, so I'll be out there again next weekend and end up cover head to toe in stucco drips.
And that's the way it is way out west.
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Snuffy "Hub Cap" McKinney wrote:

Google "skip trowel"
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On 10/2/2015 9:14 PM, Don Y wrote:

When I lived in Florida, our condo assn. got some estimates for painting stucco/concrete block bldg. with loads of mold and lots of hairline cracks. I worked on getting estimates...first, for 2 coats elastomeric paint and all the usual prep, was for $27K. Last, and the one we used, was a tad under $7K. Contractor rec. 2 coats paint, but board wanted cheap. I am not a lowest-bid fan, but this contractor was good. They used brushable caulk, which I had never heard of before, and it turned out to be a flawless job....they spent first week just on pressure washing, as the old paint job was in horrible shape and there was loads of paint that blasted off the bldg. Paint job looked great 6 years later when I left.
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On 10/3/2015 7:33 AM, Norminn wrote:

Yes, and "wet brushing" can make the caulk not stand out as a "line" under the paint.

My concerns are the structural consequences of any underlying cracks. And, sealing things up so water infiltration during winter months doesn't lead to these growing (when freeze).
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On 10/2/2015 9:14 PM, Don Y wrote:

I would start out by looking at websites for a couple of paint companies and look at the technical stuff for particular conditions. Read the recommendations for product and application. Then, so you have an idea of how one SHOULD approach the problem, get a couple of estimated from reputable paint contractors. The better prepared you are, the less they will try to over-sell and you might get additional good recommendations.
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Norminn wrote:

Some time ago, wasn't it discussed here about stucco painting vs. fogging? I asked around about fogging here and no one seems to know what it is.
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On 10/3/2015 3:37 PM, Tony Hwang wrote:

I think people get confused about different types of stucco....stucco/concrete block is almost only thing used in Florida. Stucco on lath, IDK. In Florida, it is also almost universal to use semi-gloss acryllic paint. Semi to discourage mildew from clinging.
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On 10/3/2015 7:38 AM, Norminn wrote:

We'll do the work ourselves. The issue has been trying to get an answer that doesn't just sound like "addressing the cosmetics".
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Don Y wrote:

Patching is good except matching color. Small fine cracks I, use colored silicon sealant smeared in with fingers. When kid was young used to hit the wall with hockey pucks playing street hockey causing some chips, etc. In my neighborhood all houses are Stucco walled. Lately painting is getting popular into darker earth colors. I one day I asked a painter doing the job, pointing my house which has lighter mirage color. He said,"You know, if I were you I wouldn't bother. It's like a fashion, in about few years your house color will be fine. Your walls are in pretty good shape."
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