New CMU on top of exist CMU
New CMU on top of exist CMU
(OP)
Interior cmu wall, non-load bearing, probably 6" cmu x12' high but still need to verify.
For access purposes they have to demo about half the height and then re-install matching masonry. Since most likely there isn't going to be any rebar in the wall, I am just going to let them install the new cmu on top of exising with a mortar bed ofcourse. Would that be enough for the tie between the two or do I need to dowel the two halves together. I am going to have them brace the wall at top, if it wasn't already.
For access purposes they have to demo about half the height and then re-install matching masonry. Since most likely there isn't going to be any rebar in the wall, I am just going to let them install the new cmu on top of exising with a mortar bed ofcourse. Would that be enough for the tie between the two or do I need to dowel the two halves together. I am going to have them brace the wall at top, if it wasn't already.
RE: New CMU on top of exist CMU
RE: New CMU on top of exist CMU
I am in a high seismic zone, so I would feel better if I installed verticals at 48" minimum spacing, but you might not need it in your area.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: New CMU on top of exist CMU
A few rebars and some grout is rather cheap
RE: New CMU on top of exist CMU
RE: New CMU on top of exist CMU
RE: New CMU on top of exist CMU
First thing is to get accurate information of the size, dimensions and configuration of the existing wall units, including the number of cores and webs. The 12" height is extremely rare. Are you sure are not 8" high?
If it is actually concrete masonry, you can use normal mortar to lay the new units on the existing portion.
When you remove the old section and there is rebar, do not cut it off, but retain enough to allow the new rebar and be lapped and then you can grount those cores. Use 8" to 11" slump grout and not mortar. Depending on the height, it is up to you, as the engineer, to determine the placement methods based on the height of the new masonry. I would avoid clean outs if at all possible since they can decrease the quality of the construction.
Finding 12" high units, especially in a 6" thickness, will be a challenge since they are extremely rare in the world.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: New CMU on top of exist CMU
Pardon my ignorance but I am assuming that by cleanouts you mean shell openings knocked into the side of a cmu block, right? And thanks for the detailed response, like I mentioned I still need to go out in the field and verify the dimensions.
And while I have your attention here, what do you think about a 4" interior partition wall, 10' tall, braced at the top. Ignore any seismic loads, the wall is for mechanical chases and some toilets.