Part 9 Canadian Code Strip Footings

Question

Part 9 Canadian Code Strip Footings

Woody1515 (Structural)

(OP)

7 Feb 18 21:44

Hello everyone,

I have a basic question regarding strip footing design, particularly for Part 9 structures from the NBCC (mostly residential). From my understanding, Part 9 gives design criteria for unreinforced concrete footings. Is it true that if the footing width and thickness meets the Part 9 requirements you can design these footings without any reinforcement? In my limited experience, I've seen many residential drawing packages with rebar in the strip footings.

Thanks!

BAretired (Structural) · Answer 1 · 2018-02-08 00:47:07

Yes, it is true. Some engineers may specify longitudinal steel in strip footings, but that is essentially temperature steel. In most cases for Part 9 structures, the width of footing is small. A 24" wide strip footing supporting an 8" thick wall has a projection of only 8" on each side. If the depth is 8", transverse bars are not required.

BA

KootK (Structural) · Answer 2 · 2018-02-08 00:51:16

Agreed. In addition to temp and shrinkage, some engineers like that the longitudinal bars make the footing a bit of a beam element to allow the system to span over potential weak bits of soil. Often, however, you'll have a frost/stem wall better suited to that function anyhow though.

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.

Woody1515 (Structural) · Answer 3 · 2018-02-08 17:23:24

Thanks for your responses. I figured the rebar included in these footings was "extra". I always find it tough to determine when it is required to design above the Code requirements.

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Part 9 Canadian Code Strip Footings