What size of footing do I need if I want a 24 x 24 garage with a walking deck on the flat roof? ?

Question

My inspector told me 12" x 12" is OK but I want a higher footing. Do I have to make it wider as well?

Answer 1

Hello, a 12"x12" footer is all that is required to carry the load of the building. That being said I usually pour mine 16" wide and 12" thick, these numbers are calculated by engineers to the specific area in which you are building so if the inspector said it is good, go with it. A higher footer serves no purpose, and poured to thickly can cause problems of its own. Hope this helps.

Answer 2

The key here is to the depth of the footing from grade to bottom, in cold weather climate where winter temps go below freezing go 32" to bottom of footing. If soil is sandy go with 18" wide footing x 12" thick, if soil is heavy clay go 24" wide a 12" thick. That is plenty. You are not gaining much if you go thicker than 12".

More important if you want a flat roof is the roof joist you install. If you are spanning 24' you better use an engineered floor truss designed to carry the flat roof, and occupants on it.

If you are using 8" concrete block a 12" wide footing is not enough.

Plus it does not allow you enough wiggle room when you go to square up and snap lines for block.

Excavating contractors seldom dig footings with a 12" wide bucket, it is usually 18" or 24" wide.

Answer 3

the footer should be twice as wide as the unit you are laying and at least as thick, so 16 in. wide for 8 in. block and so on...the depth will depend on your location...