Ok I’m building an addition on a friends house….I’m not a foundation man (although I have done enough of them) But my question is this– how to tie in a block stem wall into the existing block Basement foundation wall.
The house is old and has a block basement (more like a deep dirt floored crawlspace) and I am putting in a 4 foot deep foundation, planning on pouring a 22 inch wide footer and lay 10 inch block, grouting the caveties every 3 feet, with a drain on the outside daylighted out.
What do i use to tie in to the existing foundation? ON poured stem walls I would expoxy in some rebar stubs and tie them into my steel…. ????
When in doubt, get a bigger hammer!
Edited 3/2/2006 5:05 pm ET by custombuilt
Replies
epoxy rebar
what size, and do i just chip out a pice of the end block or leave a bigger joint?
Do you know if your existing block stem wall has filled cells? Probably not.
At the point of connection, I would drill holes in the block to determine if they were filled cells. If they are, epoxy the dowels and go from there to tie them to your new wall.
If the cells are empty, break out a cavity at the top of the wall and after setting your dowels and tying into your new wall, fill the old cells at the same time you are filling the new.
If you are extending the wall at a corner, that is, you are not making a perpendicular connection, drill or break through into the next cell too. Extend your dowel into the second cell and fill both cells. This will tie the old corner together better, especially if you are drilling through the side of the cell of a full block into the end of the next block.
Our dowels are usually #5 and at the top of the wall you should also have a #5 running continuously through the bond beam and tied to the verticals which in my area are #4's. The bond beam is lintel blocks as the top course and they and the next course below are totally filled. On a short stemwall, like 5-6 courses or less, I usually fill all the cells. Not worth the trouble to isolate the bond beam and hit just the cells with the #4 verticals.
Overkill? Maybe. Maybe not.
Edited 3/2/2006 7:06 pm ET by RalphWicklund
at the connection - break a couple of holes through the existing block, lay in steel, and pour the cavity to the new cavity. That will give you a knot of mud reinforced with steel
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thanks for the replies guys!
Also any tricks for tuckpointing an old block foundation? hmm....i've done a lot of brick.. It doesn't appear to be stress cracking, just a lot of the grout has fallen out.
I think i'll just tuck point them with fresh morter....but should i go ahead and fill some of the cavities? none are filled