Crack in porch foundation

We have an outdoor porch that is sitting on a slab (i believe). The one side of it has a pretty substantial crack and I'm wondering the best way to fix. Should i just get some masonry caulk and a backer rod, or should i get some mixture? I believe that they are just concrete bricks that are settling apart and/or water water hydraulicing. At it's largest the crack is about an 1/2 inch in height. The depth seems almost infinite at some points but is at least 2 inches. Here are some pictures for reference.








(16 inch ruler)

Advice, pertinent articles, or best googling terms greatly appreciated.

Thanks for reading.

I suspect that the slab is somehow connected to the house and that is what is holding it up. First I would make sure the ceiling is level in the porch check a few places, a slope there would indicate a bigger problem.

That crack looks like it is at masonry block levels.
I think the block below the slab has settled and created the void.
You have any pictures of the top slab?

I am sure a brick layer could re-point the block and this could be fixed up like new, my worry is that the front has sunk which would pull the roof away from the house. That would call for somewhat more of a fix or atleast watched closely for future changes.

What makes you think the porch is on a slab? Is your house on a slab or do you have a basement? If you dig down a little in front of the blocks, what do you find? There's a good chance that it is just another row of buried blocks. maybe a concrete pier, or you might find a slab. That will be good to know because your corner columns may need to be checked also.
What is the floor of your porch made from?

slownsteady said:

What makes you think the porch is on a slab? Is your house on a slab or do you have a basement? If you dig down a little in front of the blocks, what do you find? There's a good chance that it is just another row of buried blocks. maybe a concrete pier, or you might find a slab. That will be good to know because your corner columns may need to be checked also.
What is the floor of your porch made from?

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The slab is visable just below the brick wall, it is the deck of the porch. But your point is a good one, is there a footing and was the footing designed to carry a concrete deck and roof.

If it was mine and after looking at your photos I would say this hasn’t happened over night and I would take a wait and see attitude. I would fill the cracks as deep as I could with a mortar mixture. Don’t just put a backer and caulk the crack. Where the crack feathers out I would work that joint open a little with a chisel and fill it. The only place I would caulk is the last hairline crack. Then I would keep an eye on it after a winter and see if it opens more. If it doesn’t then I would say its ok if it did I would then start looking at footings and all the above.

That’s just my 2 cents if it were mine. Actually I have a few places that look just about like that and thanks for reminding me I should get at them before the snow flies.

I use the term "slab" more out of ignorance of proper terminology. We do have a basement but it isn't below the porch or even the room connected to the porch (which is a converted garage).

Here is a picture of the deck of the porch, just concrete, there are no cracks in it.



Here is a picture through one of the larger crack areas.



So we just moved into this house Aug 1. I think what has happened is that the downspout washed out that area (left side of photo #2) and "helped" the settling. I have installed a downspout extender and am in the process of regrading.

I've gotten the recommendation of quick fix closed cell backer rod and Polyurethane Sealant (not caulk) i you can determine if the settling has stopped. Then a permanent fix of mortar if and when all is well.

The question whether there is a footing or not. The slab is the right term to use. It appears there is steel in there so it was likely built to attach to the house and the front wall, the sides may have been an after thought just to close it up. Thge real problem is when the front wall sinks and you want to look at the joint between the deck and the house and check the ceiling, it should be level between the house and the front above the posts.
I would not use cord and caulk as the steel is visable, that wants to be incased in concrete to protect it from rusting more. When that steel rust it will break the concrete.
I think I would be cleaning up the crack as best you can and fill the void with a morter mix of some kind. Others will tell you which is best for the job.

nealtw said:

The slab is visable just below the brick wall, it is the deck of the porch. But your point is a good one, is there a footing and was the footing designed to carry a concrete deck and roof.

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Fair enough. I think of the slab as a foundation, that's what I was getting at. In this case, the slab is sitting on something else and we don't really know what is at the base. The word 'footing' escaped me last night.

I'm having trouble getting the photos but I saw one that appeared to show a void in the crack. That might indicate a suspended slab that might have been poured on uncompacted soil that has since settled. If the front has a good footing and it has a good connection to the house, the slab might be self supporting, depending on how much rebar they put in the slab.
If this was built, just some time after building the house, the side footing may be there but it may have been placed on disturbed soil that had been removed to install house foundation.

nealtw said:

I'm having trouble getting the photos but I saw one that appeared to show a void in the crack. That might indicate a suspended slab that might have been poured on uncompacted soil that has since settled. If the front has a good footing and it has a good connection to the house, the slab might be self supporting, depending on how much rebar they put in the slab.
If this was built, just some time after building the house, the side footing may be there but it may have been placed on disturbed soil that had been removed to install house foundation.

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That was my thought in post #7. With the wait and see approach after filling the crack as deep as I could with mortar. After seeing the close up I agree get the rebar covered and pack it full as you can with something solid not just sealing the crack.

My suspicion is the footer for the block wall was not adequate. Rain or whatever has caused the block wall to sag, separating it from the "slab" which was above it. You can clearly see the steel in the "slab" so we know why it is strong enough to hang in mid-air.

Analysis -- Dig along the line of the crack a few feet, deep enough to encounter the footing (if there is one). If there is no serious footing, you have to consider the next step. Typically, you want it to be twice as large as the size of the block it is supporting on each side.

Solutions -- Good for you to re-direct the water away from the foot of the wall. This might stabilize the wall all by itself. Can you underpin the footing for the block wall? Sure ... but it will be a lot of work. Can you pack the crack with cement products and take a wait and see attitude? Sure because once you have done this, the "slab" will be stabilized and you won't have to worry about a more catastrophic failure in the meanwhile. Should you use caulk and/or backer rods? NO, they are cosmetic and cannot support your "slab" in the meanwhile.