Footing Size

[chimney]

I am daftsman detailing a new foundation under an existing church; The stemwall will be cinder block (8x8x16) - so how wide do I need to call the footing? I am used to a T system and havent had to deal with block before.

[homebild]

Width of footing will depend upon the soil type, the loads, the height of any unbalanced backfill against the foundation, and your building code.

If I remember correctly, under the IBC (International Building Code), you would need at least 2" of footing projection on each side of the foundation wall.

So for an 8" wide block wall, you would need a footing at least 12" wide.

But that only presumes that an 8" wide wall could support the loads.

You'll need an architect or engineer to calculate those for you, and likley one of them to sign and stamp the plans if you need permits for this commercial project.

[Rich]

Rule of thumb for design intent drawings would be to use a projection of 1/2 the wall width. So for 8" wall I would project 4" for a total width of 16". Aside from that - you'll need to call out that somebody will need to verify soil bearing capacity and rebar layout/size. Plus the other items that homebild mentions above.