Minimum Distance Between Spread Footings 1

What if you take a single spread footing of double the size and double the area? It really doesn't matter if there is a cold joint between them as long as they are loaded equally I think.

So theoretically you can place them side by side as long as they are loaded the same.

Geotechs out there! Chime in.

Careful with your assumptions! Geotechnical studies should consider the nature of the structural loading. If the anticipated construction is 75 kip column loads and the soil is suited for 5,000 psf, the geotechnical engineer will consider the settlement potential for a 5x5 ft loaded area. If abutting footings make the loaded area 5x10 ft, then the "seat of settlement" would go to a greater depth (and the settlement response different).

Fact is if you have an existing footing (i.e., it's settled) this may be moot. Then again, maybe not. I'd ask the geotechnical engineer. If it's a soft-ish ground site or a site with an underlying loose sand or soft clay) you could trigger greater-than anticipated settlements - don't know.

f-d

¡papá gordo ain’t no madre flaca!

Overlap of stress bulbs can cause differential settlement. The stress increase is greater under the near edges of the footings than the far edges, so the footings can tilt towards each other. This is a significant problem only if the soil is pretty compressible and total settlements are significant.

A clear space of one footing width for square footings and two footing widths for continuous footings should usually be safe. If the compressible soil is more than two footing widths down or sizeable settlements are expected, ask the geotechnical engineer.

I ended up leaving almost two footing widths between footings. The footing dimensions are 5.5'x11' and I left 10' between footings. Thanks for the guidance!