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Footing Detail

Footing Detail

Footing Detail

(OP)
I am interested in your opinions on this footing detail. Notice that there is no joint between the footing and the slab on grade.

Thanks!


RE: Footing Detail

What is it that you're looking to discuss?
Personally, I would add continuous bars across the bottom of the footing, in lieu of a hooked dowel in each direction.

RE: Footing Detail

Slab over wall condition is fine by me so long as the sequence of construction works for your project (slab precedes enclosure).

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Footing Detail

If that slab ever settles good luck, because you're going to need it. I would recommend extending that wall up to the CMU. Stop your slab at the wall.
Otherwise it acts like a big crow bar and levers your wall, distressing it.

RE: Footing Detail

bigmig - you're right - I meant to comment on the fact that there is no thermal break between the outside and interior slab - in warmer climates maybe not a big deal but in the northern areas with freezing the issue is quite pronounced.

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RE: Footing Detail

I agree with the comments above. Depending on where you're located, you might want to include depth to the bottom of footing for frost.

RE: Footing Detail

(OP)
Thanks so much for your comments.

We have been using similarly detailed footings for years in Kentucky and Tennessee with satisfactory performance. A contractor recently questioned the need for a joint between the slab and the footing.

To respond to a few of the comments above:

The footing depth is always below the recommended depth by code.

Vertical masonry reinforcement is provided including embedment depth/lap splice of dowels.

Space under the slab is always backfilled with crushed stone.

RE: Footing Detail

If you are worried about the slab settling, instead of using the stub steel contractors hate as it destroys their forms, you could always make the footing 14" wide and bear the end of the slab on the 2" lip.

A little more concrete, but a lot less hassle.

Mike McCann, PE, SE (WA)


RE: Footing Detail

I use a detail like JAE marked up all over the southeast US and it works well. Of course, we don't have freeze/thaw issues that the rest of the country usually has to deal with. Anywhere else, we float the slab at the wall.

RE: Footing Detail

Why is a reinforced corner joint needed where the slab connects to the wall section? Nix the full return dowel from the slab top bars, and just let the wall bars project far enough up into the slab to create a pinned connection, resisting lateral shear. If the joint at the face of the wall is visible below the finished grade at any point, simply put in a horizontal v-notch reveal there to give the crack somewhere to hide.
Dave

Thaidavid

RE: Footing Detail

Technically speaking - to resist lateral shear between floor and foundation wall you'd have to develop the bars to full fy on either side of the joint for shear friction to occur.

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RE: Footing Detail

If they're providing a key, then technically they don't need full development no?

RE: Footing Detail

If you trust keyways....I don't after seeing so many crack through the years. But again, many don't crack.

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RE: Footing Detail

That's why I used the word technically, I'd be providing the rebar.

In reality, we'd never do this detail, we'd always have the slab separate from the wall and only dowelled at the doors.

RE: Footing Detail

Quote:

If you are worried about the slab settling, instead of using the stub steel contractors hate as it destroys their forms, you could always make the footing 14" wide and bear the end of the slab on the 2" lip.

A little more concrete, but a lot less hassle


msquared48,

Could you elaborate? It sounds intriguing but I'm afraid I wasn't able to follow it.

[Edit] Wait, it may have just hit me. You're referring to making the stem wall 14" wide, bearing the slab on a 2" portion of it and building the CMU wall on the remaining 12" portion of it? Did I get that right?

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