Applying Stucco over Concrete Blocks (CMU)

Installation, materials, and body-longevity advice from an old goat
Sept. 17, 2024
15 min read

In the video, Kirk Giordano explains how to apply a specific textured finish to cinderblock walls, demonstrating his technique and tools. He walks through the process of applying a base coat, sharing tips on how to properly cover grout lines and create a textured, jagged finish that matches older craftsmanship styles. He emphasizes the importance of understanding different materials and adapting methods based on conditions like weather. 

Kirk also rambles into stories of past jobs and offers advice on working efficiently without damaging your body. 

OFFICIAL TRANSCRIPT:

Howdy folks, Kirk and Jason here with Kirk Giordano Plastering. Today, what we're doing is I'm going to show you how to do an unusual texture. We're going to show you the cement we use, how to do it, where to buy it, and all that stuff because you may be curious.

See that pattern right there? That's an old-world finish. That just means they did it when they had craftsmanship. Today, everybody wants a three-coat system: scratch, brown, and a color coat. That's a craftsman’s work. We'll show you how we match that. I can match it with this swim-pull trowel, but I've got my square trowel too. I'll show you how we do that.

Covering cinderblock is like regular 3-coat stucco

Okay, what we're doing, guys, is covering cinderblock. When you cover cinderblock, it's the same as if you're covering concrete or terracotta. It's the same material we apply for scratching and brown coating over wood substrates. If I have paper wire, it's the same material. We're gonna show you this material soon, as soon as I warm up a bit because it's pretty cold right now. If it were raining, it would be snowing, so I'm trying to warm up.

Alright, give me some mud, bud, let me warm up these cold bones. Alright, this stuff—once we get started and I warm up—I’ll show you a little more about the materials, like how we put this on.

It was snowing when we were doing a straw bale house, and it was so cold the water hose was freezing unless you kept it on. But we took our shirts off because once you start working, you warm up quick, especially if you know what you're doing.

So, there's just a base coat. To cover the grout lines, you’ve got to go at least half an inch. Thank you, sir. If you're going to paint a wall, you don't have to go that thick, but you're best going at least half an inch.

Bonding agents help stucco stick

The cinderblock wall here—most of you folks who watch what we do know—we apply bonding agents over walls. This wall, we hit with a bonding agent. We put our bonding agent, Weld Crete, over some of the corners for specific reasons.

What I did was hydrate or mist these walls. Although they're brand new—when I say brand new, I mean built about a month ago—I took a wire brush and scored the surface. Then, I took a water hose to remove any dust that might have accumulated from things like lawnmowers. We don't want dust because dust inhibits stucco or paint from adhering well.

I did not apply Weld Crete or any bonding agent on the flat walls. We've got a mechanical bond that's even stronger. We wet this and misted it. If it was 100 degrees, my application would differ a little, but right now it's still under 40 degrees, so it's a bit chilly. One has to understand the weather, as well as the materials.

Usually, if you can apply one type of material, you can apply most. The difference is you have to know and understand what each stucco or plaster material is capable of and what it's designed for. If you're not sure, it's better to call someone who knows.

We show a lot of you folks how we do it and explain the do's and don'ts. But again, if you're not certain, call a professional.

Cinderblock does not require a scratch coat

Now, for this particular finish, I’m applying the base coat—this is a base coat or skim coat, which means the same thing. No, you don't have to scratch it. I’ve got a lot of folks who ask, "Where's the scratch coat?" A scratch coat is for wood lath with paper wire over a wood substrate. You do not need a scratch coat if you're going over concrete blocks, CMU walls, or terracotta walls—anything with a porous nature, like stone.

Corners and top-of-block details

As for the corners, it’s quite easy. I can put it on two different ways. We can squeeze a little bit of excess off, then come through the other side and do the same thing. I put a little extra stucco fat because these corners are going to be jagged. That's how you get a corner quickly without messing around. Put it on here, put it on there, and as it falls, no big deal. We don't want pretty corners; we want jagged corners because that’s what they had back then, and that’s what we want to match.

Let me show you something about the top edge. Generally, I’ll take my hawk, go like this, and pull that right off the top because we want jagged tops to match the jagged finishes of the original house.

We have one finished retaining wall around the house. I'll just take some mud and put it right here. You want to put enough mud up here to still give that jagged look and create a top. Like a pyramid, you go one way, then the other, and hit it flat. Now you can jag your corners.

We've got a little bit of excess mud, so I’m squeezing that off, getting about a half-inch on these corners. Some folks say they don't do the corners because they’re going to cap them. The beautiful thing about this is you can leave it loose, put your electricity in it, and all that jazz if that’s what you have in mind.

Texturing to match existing walls

Now, what we do is keep putting it on. I'll show you how we do these textures. This one is Jason’s favorite texture—the beard behind the camera filming me right now.

I built that corner here. Now I’m just going to reinforce it. It just takes practice. You look at it, and it doesn't have to be perfect because the finish we're doing is imperfect. If I made it pretty, I'd be defeating the whole purpose.

I'm going to do one last thing and show you some other stuff. Alright, I’m finally getting warmed up. It's a cold day out here—everybody's walking by with earmuffs and ski jackets, and I just took mine off. I don’t want to get stucco all over my jacket.

Alright, now I’m going to take off the last little bit here. Even though I’ve wet these walls for a mechanical bond, which is actually stronger than any bonding agent, it’s still wet. How long will this take to dry? If it was about eighty degrees, it would already be dry. I'd have to keep misting it with water as I'm plastering because it would suck up the moisture right out of this Portland cement.

Stucco mixes vs. mixing your own with Portland Cement and sand

What does Portland cement... excuse me, fellas, let me get over here. I want to show these guys something because I can. This is Lou's job.

Folks ask, "Why do you always say, 'Luuuu,' like that?" Because of the Mary Tyler Moore Show. Lou's all right. Anyway, this is... a lot of you guys think, "Kirk, I'm going to Home Depot. I'm going to Lowe's. What material do I buy?" I say, "Buy a Portland cement, buy some sand, or what the heck." I say, if you're going to Home Depot, buy the Rapid Set. It's a product that has sand in it and cement. All you do is add water.

Here's how we professionals do it, okay? We bring a yard. Like this morning, I got a couple yards of sand. Now, what’s a yard of sand? It’s 2,400 pounds. A ton is 2,000 pounds. So, you get your sand, and then you mix your cement plaster.

There are so many different cement plasters, I couldn't name them all here and bore the crap out of you guys. I just prefer this one here, sold at the material yards. It's a cement that has common cement, and it also has lime in it, so it has everything all in one bag. And what is this? It's a Lehigh. Lehigh is making this all-in-one. It's premium. That way, I don't have to get separate bags of plastic and common—that's a whole other story, and I won’t get into it.

The truck we use, of course, has everything. A fella says, "How do you have, like, 20 of these?" Yeah, I got about 15 of these because we use them. We use everything. We come to a job like this; we have everything. The way we do it is we come to a job once. I don't leave the job five, six, seven times to go back and forth to get materials. I have more materials than I need for every job when I get to that job.

Covering radius walls with stucco

Anyway, guys, we're going to continue moving here, and when we get to these radiuses—piece of cake. Close our eyes and go around them, and do the tops the exact same way. I'm not worried about getting mud on these stairs because they have two-inch flagstone going on this. So after we get all this done, we just take a trowel and trim it right out because it's all going to be covered.

Let me show you a few more tips since we're here. All right, we're on a radius wall. Do you have to take it like this out of radius? Not really. Because it's such a large radius, I'll just take it... and just like I did on the other side, I'm taking it here, and then I'll come back to it.

PRO TIP: Catcher's shin guards are better than knee pads

By the way, guys, you might be wondering, anybody watching and sees what we've done over the last ten years... a lot of people say, "Hey Kirk, how come you don't wear knee pads?" Well, when I was working Union, we would stucco about anywhere between ten houses a day with a gun. We'd go through 20 tons of sand and 200 bags, and I did wear knee pads. I was wearing these catcher's knee pads. Why? Because these catcher's knee pads—they're comfortable. These aren't as comfortable as a lounge chair or a hammock, but they don't fall off, they don't slide down, and they don't cut your blood circulation off.

So, I know someone's going to comment and say, "Kirk, what kind of knee pads?" They're catcher's knee pads from baseball. And another thing too, guys, is because I don't want to jack up my elbows, like, say, here—I'm just being lazy. Now, watch. I do this... the bottom is gonna go on the ground, not my elbow. The hawk tip is gonna go out, and I'm putting all the weight on that tip while holding it off. And I'll do this, guys. I'm putting the mud on the wall. What I'll do sometimes is hold off the sack as I'm putting it on, and if I have a seat right now, I'm on the tip. I'm not on my elbow. I'm on the tip.

Simple movements that reduce strain on your body

Just have it, guys. Make some of these things, especially your apprentices who watch what we do—make these things habit so you don't jack up your elbows. Now, look, my hand is not on it or my elbow. Now, I'm using it. I'm going down. I'm using a hawk, kind of like a crutch. Man, I'm here or here. I'm never on my elbows, especially on concrete.

I'll show you a couple of things too while we're at this because what we're gonna do is knock this out, but I want to show you a few basics before we even lift it up. I'm lifting up—everything is with my crutches now. Jason is spreading the texture over this tire. Everything. Jason is really good at textures. You put your pancakes in it, guys. There's a lot of ways to do this.

Stucco and concrete mix recipes

If I were to let this turn light gray, like the color of this when it dries, it's going to be that color. That's Portland cement. Here's concrete. It's Portland cement with rocks. Stucco or cement plaster or render, as they say in the UK—all that is, instead of rocks, it's Portland cement with sand, so it's a tanner color because of the sand. The rocks are usually lighter. So that's Portland cement, and this... this is going to dry like that. There are three to five different ways to do this.

Floating the final coat

Jason just put this on. Now, you let the whole wall set entirely and turn this one color, and what Jay is doing is this. He's just taking each one, and he's taking a sponge float. A sponge float brings out the sand or aggregate. Now you bring out the aggregate, you just let it drip on it— a lot of water, guys, you just let it drip. You see how that's dripping down? It's not gonna hurt the wall. That's actually good for the wall. Just a lot of water, guys. I mean, you could use a lot of water depending on the size, depending on what type of pancakes you're putting on it or trowel marks—no water or a lot of water.

And yeah, you could use a felt brush. We used felt brushes when we were working at Union for interior coating, but you can also just use the brushes here. And the more water you put, you're gonna take away the sharpness of this, so depending on what you want, I use a little water or a lot of water. Anyway, guys, we're gonna continue moving, and when we get done with all of this, we'll show you.

Lou, he's doing another mix, and that's how we do it, guys. We take the sand from the back of the truck and do individual mixes. Edgar here, my nephew, just happens to have the day off. He's working with us. This guy is the bomb—it makes my life so easy. You're spoiling me, brother.

Anyway, we're gonna continue moving, then we'll show you the end result. Alright guys, I'm going to show you the final of this. Now, as you can see, this is what the owner wanted. We're here talking with him and discussing things. As Jason says every day, everybody has a different fingerprint as far as a different texture. This is what floated his boat. He's happy, so we're happy. There are a lot of different ways to do this.

Jobsite truck repairs

When you're a big-time stucco guy, a lot of different things happen on the way here. I was huffing and puffing, turning that truck. That's a nightmare without power steering. I thought, man, I gotta put in this power steering before we leave to go home. No, I don’t. This is what’s left of my power steering belt—no power steering belt, no alternator, no water pump. I can't drive that. We're in San Anselmo, that's an hour and a half away from my house. So, wait, and Jason is about to get off the camera and go get all the belts—all four—and another alternator. We're gonna have some fun and stay here till dark and put it back. The life and times of a big-time contractor.

Anyway, my name is Kirk, Jason on the camera. We thank you guys for watching, and as usual, live long and plaster.

Hey, I forgot to tell you yesterday because I was sidetracked with what's left of my fan belts, but we got this truck here. We were an hour and a half away from San Anselmo. We fixed the truck somewhat, but we're getting ready to go to work now, and it's just as cold. And because we're not mechanics, we've got a whole thing of oil over here. So you want to be a big-time contractor? I wanted to tell you guys, my wife brought me a cup of coffee as she saw me freezing my arse off. And fortunately, Carl, my neighbor, he's a 40-year Ford mechanic. I have turned this over to him just like sometimes you guys turn the stucco over to me.

By the way, what I missed yesterday to say was, if you guys want to see how that texture was put on, I'm gonna put a link in the description to Jason's channel because he did all the texturing. All I did was apply everything, and we got out of there.

Anyhow, guys, we thank you for watching, and take care of your vehicles. By the way, folks, my dad and I are now members of Amazon Affiliates, so if you're looking to buy any of the plastering or construction tools you've seen in our videos and you want to support us in the process, you can check the links below our video or you can go to our website and get them there. If you have any other questions for tools we don't have linked, email us directly, and we'll respond to you. Once again, folks, we thank you for watching, and I really enjoy all your comments. If you guys like this video, please click the like button down below. And also, if you enjoy what we do, subscribe to our channel so we can keep making these videos for you. My name is Kirk, and Jayson... we thank you for watching, and from the entire Giordano family, we'll see you on the next one.

About the Author

Kirk Giordano

Kirk Giordano is a plaster and stucco contractor in the San Francisco Bay Area. His YouTube channel has a lot more videos.

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