Why is it important to install rebar in footers?

Answer 1

Installing rebar in footers helps the overall strength.
The foundation of a structure is most commonly built using layers, beginning with topsoil and foundation excavation, leading through frame pouring and footer mapping, and installing rebar and concrete into the footers. The rest moves from the ground up.

Answer 2

General answer: concrete is great under compression, but fractures easily under tension. Steel is just the opposite: it has high tensile strength and is great when pulled (under tension), but weak under compression (push and pull a piano wire and you'll see)

Imagine a concrete bridge. The pillars are under compression and thus have less steel rebar than the concrete girders/beams spanning the pillars, which have lots of steel, especially under tension near the bottom edge.

Foundation footers are like the bottom girder on a bridge. If the subgrade is improperly compacted, the steel will help "bridge" small soft spots in the soil and prevent the concrete/steel footer from cracking or breaking. If you could be 100% certain that the subgrade was compacted and would never move, then you don't need the steel. Practically speaking, however, this is never the case.

Answer 3

Overall strength. The footers are also subject to ground movement with changing temperatures. This could cause the footer to shift and break if not reinforced with rebar. In Florida, I even had to have it in a porch which had nothing on top of it, even an awning.

Answer 4

The footer supports all the load above it, some times thousands of pounds.Although concrete resists compression the tensile strenght is an important factor, steel provides this and resists cracking along the length. Footer failure translates to cracking and excessive settling in the structure which can lead to a lot of problems.