Using vertical rebar to suspend footing rebar for CMU stem wall
I will be pouring an 8″ thick by 16″ wide footing into the bottom of a 16″ deep trench and then building a 32″ masonry stem wall for the foundation of a small house. Code requires a continuous horizontal rebar 3″ from the bottom of the footing and a vertical rebar with a 6″ hook, also 3″ from the bottom of the footing, every 48″. I’ve cut and bent the verticals so that they will extend high enough to tie them to the horizontal #5 rebar resting in the 2-1/2″ deep groove in the bond beam, but not so high that they will protrude above the finished stem wall. It seems that the best way to make sure the verticals reach just to the height I want would be to tie them to the footing rebar and to 2x4s that straddle the footing trench, using the vertical rebars to suspend the footing rebar the required 3″ above the bottom of the footing. To keep the 2x4s from sinking into the soil and to give the 2x4s more height to better hold the upper part of the vertical rebars, I would place the 2x4s in the U-shaped grooves of bond-beam blocks that would rest on standard concrete blocks with their solid surfaces down.
I’ve thought of two drawbacks to this method:
1. It may take an hour or so of extra work to set all of this up.
2. The vertical rebars will make leveling the top of the footing slower.
The alternative would be to hang the footing rebar from wires attached to 2x4s and then push the vertical rebars into the footing while the concrete is still wet, but setting that up won’t be all that much easier, and keeping the verticals at just the right height would be more difficult.
Does this method make sense, or am I overlooking something?
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Replies
Jeff,
Below are some photos to give you some ideas. You can trowel the top of your footing, even with vertical rebar protruding.
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Extremely helpful, Martin; many thanks!
We always have two bars at the bottom of the footing. We set them on dobie blocks, and then start tying the hooks to them. Once some of the hooks are in place, we start tying in the horizontal bars that will be in the stem wall. It takes a bit of fussing but you can make the entire thing self-supporting, and then start building the wall forms. Once the wall forms are in place we might use a bit of tie wire here and there to keep everything where we want it.
Martin, the photos you posted do not show the type of corner joint we use, in which the outside bar turns the corner to become the inside bar, and vice versa. It's what the inspector here wants to see. I've never actually looked up a code cite for it, we just do it.
Don't forget to have the electrician put a wire in the footing for a Ufer ground.
Thank you, David.
In this situation for the vertical rebar, this is an excellent product and solution - http://www.steelmate.com