I’m about to build a small (4′ by 6′) addition. The foundation walls will be concrete block veneered in brick, same as the existing foundation. What the best way to tie the new walls into the old? Is rebar driven into the block to connect the footers enough?
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Replies
The new footings need to be at least as low as the existing- otherwise they'll be sitting on backfill material. You can then drill and dowel the new to the old. With the block/brick, I'd remove the brick veneer where the addition sits, and grout the existing cells of the CMU solid so that you can dowel into it to tie the new wall in. Some designers would say to simply set the new block against the old to allow for some differential movement (maybe with a felt expansion joint between). But at a minimum, I'd tie the footings together. What does your architect/engineer say?
Bob
How do you grout the existing CMU's? There are solids on the top of the foundation wall and a house sitting on top of that....
Cut out the face of the top block and dump grout down the cells, then patch in the face that you removed.
Bob
What Bob said.....
Also, I have seen threaded rod run through the existing foundation (assuming basement access), centered on new foundation wall (perpendicular joint), extened at least to first core of new block foundation. Put a large washer & nut on both ends of the rod. Grout core solid (with nut/washer included), all of the way up. Once it sets, tighten the nut/washer on the inside of the exist foundation wall. This helps to reduce the risk of the addition from seperating from the existing foundation. Once again, this works for perpendicular joints.