Multiple Course CMU Lintel Construction
Multiple Course CMU Lintel Construction
(OP)
Hey all,
I have never designed a multiple course CMU lintel before without just using 16" U-shaped blocks. What is the typical way to construct a simply supported lintel with say 3 courses required? Would you first place a set of 8" U-shaped blocks with reinforcing, place two more courses of standard blocks above, and grout the whole thing solid? What about continuous lintel? Would you knock out the webbing of the standard blocks to place top reinforcing where needed? If anyone has a sketch or a standard detail they are willing to share, it would be greatly appreciated!
I have never designed a multiple course CMU lintel before without just using 16" U-shaped blocks. What is the typical way to construct a simply supported lintel with say 3 courses required? Would you first place a set of 8" U-shaped blocks with reinforcing, place two more courses of standard blocks above, and grout the whole thing solid? What about continuous lintel? Would you knock out the webbing of the standard blocks to place top reinforcing where needed? If anyone has a sketch or a standard detail they are willing to share, it would be greatly appreciated!






RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
I could be wrong. Just stands out in my mind as one of the reasons I haven't been able to use non-masonry lintels in the past.
Crackerjack...sorry, I am not able to answer your question. But I will be following the answers!
PE, SE
Eastern United States
"If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death!"
~Code of Hammurabi
RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
In my practice I've only done fully grouted masonry and all lintels at openings would be constructed pretty much as you describe. A lintel or inverted bond-beam block at the bottom and another a bond-beam course at the top. Horizontal reinforcing provided according to the demand in bending and vertical reinforcing based upon beam shear (hooks may be required on the ends of the vertical bars for anchorage). For lintels with large tributary areas/spans out-of-plane bending may need to be considered too.
regards,
Michel
RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
If I need a lintel that is 32" deep, the bottom course would be a U-shaped block (#85 in Spats' document). Assuming the wall extends higher than the required 32" lintel, would you just use standard blocks for the three courses above the U-shaped block and then grout the entire 32" solid? Or would you use one of the flow-through type blocks for the (3) upper courses of the lintel?
RE: Multiple Course CMU Lintel Construction
That's true... I'm just not a big fan of precast lintels, because I've never really found a satisfactory way of specifying them. Cast-Crete, for one, has a too complicated naming convention for specifying. I worry about them just pulling something convenient off the shelf. Specifying gravity loads, lateral wind loads and uplift loads is too complicated. How do you specify?
RE: Multiple Course CMU Lintel Construction
Yes you can use standard block in the three courses above and fill solid. The only problem I see is if they forget to fill the upper blocks. Even if you don't need top bars, I usually put them in to remind the contractor that the whole thing is the lintel. 32" is a pretty deep lintel... have you checked shear? The top bars also provide mechanical anchorage to help develop the vertical shear reinforcement, which needs to be hooked around the top and bottom bars as stated by Michael60.
RE: Multiple Course CMU Lintel Construction
regards,
Michel
RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
If I had to guess, I'd say that the masons around here prefer not to involve another trade when they can fairly quickly build up wood shoring to support most lintel construction. I remember one or two contractors who would use something like a Powers Steel lintels in lieu of shoring but still construct them as masonry lintels.
http://powerssteel.com/lintels/index.html
As for the block, I often saw the masons cut out one of the end shells of a typical 8x8x16 to gain the requirement that no air gaps remained in solid grouted lintels. Or an open bottomed bond beam block with one end removed where there was horizontal reinforcing.
RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
regards,
mk
RE: Multiple Course CMU Lintel Construction
Precast lintels and steel lintels in block walls cause too much discontinuity for my liking.
RE: Multiple Course CMU Lintel Construction
hokie66 they have a slot for vertical reinforcement placement at the ends.
RE: Multiple Course CMU Lintel Construction
Dik
RE: Multiple Course CMU Lintel Construction
Also, if the structure uses pigmented or split architectural units, it is easy to satisfy the architectural or appearance requirements using units that may normally be on the job.
Every location of the country has preferred shapes that are made to satisfy local preferences and needs, especially in seismic controlled areas. There are many variations in what people think are standard units and one mold manufacture has a file of over 1500 different variation of just 8x8x16 CMUs and a dead file of molds not ordered in last few years.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Multiple Course CMU Lintel Construction
Thanks, but I was talking about horizontal continuity.
RE: Multiple Course CMU Lintel Construction
We are talking about grout filled U shaped precast lintels right.
RE: Multiple Course CMU Lintel Construction
The major difference is the appearance and whether it is site built (quicker) or from a supplier that may have standard lintels that size and reinforcement readily available for construction.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Multiple Course CMU Lintel Construction
RE: Multiple Course CMU Lintel Construction
Our terminology seems to be the problem. I thought you were talking about a precast, reinforced solid lintel. The U-shaped precast lintels you are talking about are new to me...not available in Australia to my knowledge. We just use U-shaped blocks, and the builders build wood shoring without complaint.
RE: Multiple Course CMU Lintel Construction