Dogs and concrete control joints

liberty bell

Here is a picture of my dog, Hedy Lamar. Also, the red arrow on the picture is pointing to a concrete joint. How does one detail this type of joint? Or does just call for the concrete pad to be sawcut (per a joint pattern plan that one also provides) and leave it at that?

Sep 7, 19 3:38 pm

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You draw it. 

Sep 7, 19 3:43 pm

Good question, Donna.  I always assume these thin scorings to be saw-cuts in a single slab rather than a joint between two slab areas.  (The line nearest Hedy's right paw appears to be a true joint in that regard.  I might be wrong, though.)

Sep 7, 19 6:35 pm

The line near paw is an expansion joint


Saw cut control joints, cut them 1/4 the thickness of the slab min...I usually say 1/3

Sep 7, 19 7:38 pm

Good rule for control joints is every 8-10 feet min...expansion joints every 25’


no it's not


15’ max meant to say...


Or 25-35 times thickness of slab...

Looks like pavers to me.

Sep 7, 19 9:54 pm

thinking the same thing, it's not altogether too easy to saw cut concrete, this straight, this thin, with a radial saw and not have it chip or spawl.


Although, not seeing the depth of the "cut" it could be a stamp too.

Wood Guy

The joints you're pointing to look to me like they are saw cut. As others have said, min. 1/4 the depth of the slab. It's not that hard to cut in a straight line if they take care, though most don't. There is no guarantee that cracks will happen at the control joints; I've found that slow-curing is much more effective against noticeable cracks, but the joints won't hurt anything either. If you care what the pattern looks like, draw it. If you don't care, just call out the min and max spacing. The closer the better if you want to actually avoid visible cracks. 

The bigger joints were wet-tooled with a special trowel. Possibly all as one pour, or possibly as separate pours. 

It also looks like it has a washed finish, with the surface cream rinsed off to expose some aggregate and provide a slip-resistant texture. Or it's old enough that acid rain has done the same thing. 

Sep 8, 19 11:19 am

Cutting with a circular blade means kerf depth at the end of the cut is zero. Not so hard to cut a straight line, not so easy to get it to stop in exactly the right place every time. A look at the perfectly rolled edges also indicates precast. As you point out the finish is not floated, which means polished in place - which isn’t going to a happen on a sidewalk. Concrete subs are not that delicate, and the ones that are aren't doing sidewalks.


Perhaps they poured the walk first, cut it, then cast the curb / perimeter. If it was part of a building project there's no reason it couldn't be done by a skilled crew.

Wood Guy

Miles, if you zoom in above the arrow, it looks to me like the kerf is only about 1/4" or 3/8" deep. If they used a 7 1/4" saw blade set to 1" deep and over-run the end by 1/2" it would end like that. But you're right, it would take more attention to detail than the typical concrete contractor provides.

On the other hand, the flatwork contractor who used to do the higher-end homes I worked on would fill in when local cities needed flatwork done; in fact he poured my mom's concrete driveway after the city tore it up, and he had excellent attention to detail. The joints look too perfect to me to be individually set pavers. But who knows. It's certainly a higher grade of work than the average sidewalk. 

Sep 8, 19 2:37 pm
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Oops I had forgotten I posted this while I was walking the dog yesterday!

I should point out that this is a patio outside Michael Graves' Indianapolis Art Center, which outside of using EIFS is an excellent, wonderful building.

Also it's definitely a cut slab, not pavers. I could see the surface texture (broom finish?) continuous from one side of the sawcut to the other.

Yes, that joint close to Hedy's foot is a control joint that was formed in.  The thinner joint is definitely sawcut. I did some research on concrete forums last night and it sounds like it's truly a qualified concrete craftsperson skill to be able to cut straight, clean joints like this! This slab is over 25 years old, and it's showing some wear at the cuts in a few places, it's overall in excellent shape.

So, tintt, you're right. I'll just leave the means and methods of getting an acceptable cut to the contractor, but I'll draw the pattern I want, and I'll ask for a site meeting to confirm before the pour.

Sep 8, 19 3:31 pm

Nice work. Wonder if that contractor is still in business.


Do you every call your dog Hedley just to make yourself giggle?

Yes, I do. And I say it that way.


I've seen them scored with a rope while the concrete is still wet. They are then further tooled to achieve fhe final depth. Then they get sealed. 

Sep 8, 19 5:08 pm

Tooled like so

Sep 8, 19 5:09 pm

Excellent image. 

(And your caption reminds me of a very proper British porno I saw once.)



The flange of the grooving tool is absent from Donna's image.


Donna's pic is not a wet tooled joint.

Oh wait I see a hint of it now on the edging side ... I think.


The one by the paw might be a tooled joint.

Wood Guy

I can see the trowel flange marks on Donna's image, though just barely. The surface was washed or brushed after it was troweled, which conceals the marks. And then 25 years passed.


Should also be noted that trowelled is a ton cheaper than cut, particularly if you are doing something like 45-degree with some tight corners. Also, a cut joint is weaker than a tooled one, so it will usually crack in the joint. Thus its also the better if you are coming to a point like Donna's picture if you want to avoid cracking off the corners.

atelier nobody

Courtesy of the US Army Corps of Engineers.


Sep 9, 19 1:14 pm

It’s worth noting, your resident archinect landscape architect, j-lax, accurately described what is pictured in the second post from the top. Fwiw the finish looks sandblasted, not broomed.

Sep 10, 19 7:56 am

j-lax is a landscape architect? I didn't know that.

( o Y o )

Even a blind chicken occasionally finds a kernel of corn.

Sep 10, 19 8:04 am

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