Basement walls.?

Question

How thick should a 9 foot tall poured basement wall be to support a 1300 sq foot two story framed brick house?

FORGET MINIMUM CODE! What is a realistic thickness if you want the house to stand for more than 20 years without having cracked walls?

And how long should the concrete set before starting to build on it.?

Answer 1

Tio is correct, however there is no guarantee that 10" walls won't crack either.

Answer 2

In the South we often use 8 or 12 inch concrete blocks with 1/2 inch re-bar coming out of footings (minimum footing 8"x24") then fill the block cells with concrete. 8" block gives 4" slab, 12 inch gives a 8 inch slab. Use the 12 inch if supporting brick above ground level.

Followed with the proper water proofing and french drains you will have a very good wall. I have them this way on 2400 sq.ft brick homes for over 26 years.

Total strength of concrete is after 28 days. We let walls stand over week end and start building on them.

We do not do any back fill until the home is built. The walls are also poured before pouring the basement floor. This gives extra strength against the inward pressure from back filling.

Don't forget to set anchor bolts while concrete is poured.

To lessen the chances of cracking, prevent it from drying fast. You may hose the blocks several times a day if the temps are high. You may even spray water inside the blocks before pouring and rod-ding to keep from having hollow spots in the wall.

Answer 3

10" with 3500psi concrete will rebar would be plenty strong.before backfilling put a water proof membrane around the outsideand with good drainage tile you should have a dry basement