Allowable cmu wall height during construction
Allowable cmu wall height during construction
(OP)
Are there any ACI or other code limitations on how high cmu walls can be built in one day? Obviously an 8' high wall is not an issue, but what about 10, 15 or even 20'? Will the mortar have issues?






RE: Allowable cmu wall height during construction
RE: Allowable cmu wall height during construction
This could conceivably be an issue if you have a large crew and a short wall.
RE: Allowable cmu wall height during construction
Link to ASCE/SEI 37-02
RE: Allowable cmu wall height during construction
BA
RE: Allowable cmu wall height during construction
When you're constructing CMU walls over 8', wind becomes a factor as stated previously. A masonry block wall can be constructed up to 8' in winds up to 35mph winds during the initial period. The initial period in the first working day and the intermediate period is any time after the first working day until all structural elements are in place as designed. Say you were constructing a 21' wall, 8" 125psf CMU's w/ S type mortar. From BMW, T4.2, the max height is 14' for the initial period, by the end of the day a brace would need to be placed at a height 11'-4," BMW TA1. This table also states that the max unbraced height is 5'-4," 14'-11'-4" = 2'-8", less than max. ok. The remainder of the wall could be built the next day. There also needs to be a restricted zone that must be evacuated when the winds exceed 35mph.
To answer your last question, a Masonry Contractor w/ some substantial experience could use the BMW. If it's not stated in the subs contract the they need to have a bracing plan, that it's up to the GC to provide a safe work zone for all that enter the site.
RE: Allowable cmu wall height during construction
RE: Allowable cmu wall height during construction
This is to safe guard against the squeezing of fresh mortar and minor disturbances when setting which can lead to a rounded profile to the hardened mortar and reduced bond at the ends of the units.
Kieran
RE: Allowable cmu wall height during construction
RE: Allowable cmu wall height during construction
Mortar is not a major factor in the strength of the wall assembly since the major factor is already at 90% to 95% of ultimate.
Here, 9' to 10+' basements are commonly built daily. From an appearance standpoint, you must make sure they do not tool the joints too quickly. It is very similar to grouting where 8" to 11" slump grout is required so the units can absorb the excess water from the mortar quickly, but the load speeds that up and provides stability.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Allowable cmu wall height during construction