precast lintel 1

[cmrdata]

Could anyone shed some lights on the 16 foot long precast lintel I plan to use for a non-load-bearing interior masonry wall?

1. Does the precast lintel somehow need to be positively connected to the CMU at jamb, with dowels? If so, how?
2. Does the rebar in the CMU wall sitting on the lintel need to be doweled/drilled into this precast lintel, or if grout would be sufficient to hold them together?
3. Whose responsibility is it for the design of this precast lintel? Should EOR call out and detail the reinforcing in the precast, or should it be precaster' responsibility?

Thank you.

 

[UcfSE]

1. No special dowels. The precast lintel (pcl) will bear on the masonry jamb. I recommend bearing it on a grout-filled reinforced cell each end. Continue the cell reinforcement bar through the end of the pcl. It is cast with a cut-out at each end. Often the cut-out is not large enough and needs to be field-enlarged with a saw or hammer. The cut-out needs to be large enough to let the cell reinforcement pass through continuous to the top of the wall and allow grout to flow to the cell below.
2. The bars reinforcing the wall above the lintel should be hooked into the lintel. When the lintel is filled the bars will be developed. Check that the depth of fill in the pcl can provide the hook development length for the vertical bars above.
3. The pcl manufacturer should provide load tables or some such data for vertical and lateral loads such that you can choose an appropriate design strength for the pcl and reinforced cmu courses above, if needed. CastCrete has a good set of data tables, but they are specific to that manufacturer (which is typical).

 

[BAretired]

1. Yes, I would let a couple of bars project beyond the lintel at each end and cast concrete around them after the adjacent block course has been placed.
2. Grout may be enough, but I would prefer some nominal dowels from lintel to CMU at perhaps 4' centers.
3. Design is the responsibility of the EOR. In some jurisdictions, he may delegate it to the precaster, but for something this simple, it is preferable for the EOR to design it.

BA

 

[hokie66]

I think there is some talk at cross purposes here. The OP seems to be talking about a solid precast lintel, while the replies are for a lintel to be filled on site. Or maybe it is me who is reading incorrectly. At any rate, the whole thing need to be tied together.

 

[BAretired]

hokie, I was thinking about a precast, solid lintel although I must admit I have never specified one. To span 16'-0", it is going to be pretty hefty, probably 1000kg or more. The practice in my neck of the woods would be to use either a steel beam or a CMU lintel to be filled on site. But if there is a lot of precast on the job, it may make sense.

BA

 

[hokie66]

Yes, there are a few ways of doing it. Where I am, the lintel would just be part of the masonry wall. Lintel blocks supported on shoring, reinforcement installed, the lintel filled as the wall above is filled. We do tend to fill all cores in a wall like this.

 

[haynewp]

Cast-crete is made specifically for use with CMU. I would use them instead of a solid precast lintel anyway. It may work by the Cast-crete tables for a 16 ft span and non-load bearing wall with running bond above the lintel.

 

[cmrdata]

My sincere thanks to all of you for the suggestions, which is exactly what I'm looking for.
Hokie66 was right that I was thinking about solid lintel such as the load table listed in the NCMA TEK. With solid precast lintel, it makes the dowel suggestion provided by UcfSE and BAretired difficult to execute....unless I'm missing something here?

I did see the load table provided by Cast-Crete with U shape precast lintel that works just like UcfSE, BAretired, and haynewp described. Why did not pursue it? this is a one hundred million dollar project with a lot of precast panels, metal panels, curtain wall, etc., you name it. But I have only two such lintel for the entire project. I therefore figured it would be more cost effective to use non-proprietary solid precast lintel (provide by the precast cladding supplier), instead of using the proprietary Cast-Crete products.

However, back to my 2nd question, I think Cast-Crete's U shape lintel is the only way to somehow tie the CMU rebar above with the lintel together. Otherwise, I'm not sure how we can tie them together.

 

[BAretired]

With a solid precast lintel, I would expect you to provide dowels projecting up into the wall above. It is standard practice with masonry on concrete grade beams. Where is the problem?

BA

 

[hokie66]

The other way, without procuring two special precast sections, is just build them with 8" high x 16" long U-shaped blocks, with enough courses of knockout blocks above the lintel to give you the required depth. This requires temporary support for the masonry above the opening, but that is the way we do it all the time where I am.

 

[UcfSE]

So you have a $100M project and you're worried about the cost of two precast lintels?