I would like to build some bearing walls on an existing 4″ slab. Assuming 3000psi concrete which is sitting on 3000psi sand, the loads would not be significant. But as I understand it, code specs a minimum of 6″, or is that just for a concentrated load such as a bearing post? If required for a wall, can I legally put down 2″ cement brick and then place the bottom plate? This of course would not be transferring the load over any greater area.
Thanks for any help!
Replies
Unless this is a doghouse, shed or chicken coupe, the edge of a 4 inch slab is not a good idea.
better to put in a proper foundation.
Codes depend on where you are. Local code officials will be able to point you at the applicable requirements.
Am I missing something perhaps? When I do rough calculations (walls 16psf, floor 45psf, roof 55psf) I come up with 18 pounds per square inch total load.
Yes, you are, the edge of the slab is not the same as the center. On the edge, there is no support on one side and rotational forces come into play as well. You can dig out under the edge and pour more concrete to create a real footer if you don't want to cut the slab.
I think you’ll find the sand at psf not psi
Is the slab reinforced?