We’re bidding on a ramp job for a church. Currently there is a 8′ wide by 4′ deep porch or stoop about 16″ high. We’d like to extend the stoop from 4′ out to 8′ out, making it about 8’x8′. Prob would demo everything as the brick facing on this is damaged. We’ll exc a footing to carry the new portion and lay 6″ block for the perimeter . Would leave the front n portion of the wall intact to support the slab in the center. Are we risking a crack at the center? Would rather not put an exp or control joint in this slab (about 5″ thick).
Thanks
Replies
If you try to pour the new concrete tight against the old, you will certainly get a crack as the new concrete cures and shrinks. No way you can avoid a crack ... you have a cold joint. Go ahead and pour it, then wait a month and add a layer of slip resistant porcelain tile, with a crack reducer membrane.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
If I am understanding you correctly you are going to take out the old concrete but leave the wall underneath it. If that is the case then yes it will work just fine. If that is not the case then you can pour the new concrete up against the old and just edge the new with an edger so that it looks like a normal control joint between the new and old.
Or you could put a strip of isolation joint material( commonly referred to as expansion material... looks like celotex) between the old and new and then edge up against that instead of the new.
as long as you are going to support the new crete at the porch edge with block then I wouldn't bother to tie the two together (old and new) as the new footing and block should take care of the problem of settling.
I 'm not a big believer in using the isolation material myself as it usually rots out after a few years and allows debri and dirt to fill the gap which then freezes and pushes the two slabs apart little by little........ more dirt enters and freezes ..... slab gets further apart ........ you get the idea.
Better to just pour the new up against the old and then use a quality concrete crack / control joint filler to seal the joint. Euco makes a good one as do others. This is a much better solution than expansion material.
good luck with it.
Mark
Just to clear things up. The existing cap would be demolished. My concern was minor settleing of the new portion of the footing causing a crack. I used to be in the block business and I know that no one would ever tooth a masonry wall into an old one due to the setttleling of the new one. Prob less of an issue with this being only 16' high. thanks
bump
if you pour a big enough footer, it be fine. But compact the subgrade too.