Embed Plate on Top of CMU Wall 1

[Gopher13]

I have a question about where the top of an embed plate is typically placed with reference to the top of a cmu wall. Please see the attached sketch for reference. Option 1 shows the plate sitting on the top of the wall (bottom of the plate is at the same elevation as the top of the wall). Option 2 shows the top of the embed plate level with the top of the wall. And option 3 also shows the top of the embed plate level with the top of the wall but with the cmu flange notched (this would maybe be done if the plate is too wide to fit between the cmu flanges).

I have seen it detailed all three ways but was wandering what is typically constructed. I would typically think they would construct it how it is detailed, but my experience with masons is that they kind of do whatever they want.

I am curious because if I call out a deck bearing elevation on plan as some elevation that matches cmu coursing, and option 1 is what is typically done, the very top course of cmu would have to be cut to a depth equal to the thickness of the embed plate.

Thanks!

 

[MrHershey]

Most of the masons I've worked with have been fairly lazy, so I'd guess 1 is most popular because there's less steps for them. Just set the embed plate on top, don't have to worry about figure out how it's supported or cutting blocks.

 

[KootK]

In many cases, I think you'll get the wet set plate on top. With a roof deck connection, it's almost a certainty as it wouldn't affect elevations much regardless. If it's a floor connection, like at a steel joist seat, they'll often notch out the block because:

1) not always at even coursing anyhow.
2) tough to accommodate the dimensional overrun in floor stuff.

More than a decade on, I still often struggle to predict what masons will do in a given situation. There's a selfish part of me that would like to see it just disappear as a construction material. Luckily, economics matter more than my personal comfort.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[DETstru]

Option 1 makes it easiest on the mason. If you have no reason to use Option 2 or 3, just stick with Option 1.

 

[dik]

The 'U' block is good, good idea to provide a bond beam. Detail 1 is good and common. Plate elevation should actually be established by the beam location. It's cheap to locate it on top of the block, but depth of beam may dictate where slab or steel deck are located, and sometimes best to cut the beam bearing block at the elevation required.

Dik

 

[hokie66]

I have never used a wet set plate like that. Where I am, masons won't do it, for good reason. If you want the plate to be at the right elevation, use chemical anchors into a grouted wall.

 

[dik]

Common practice here... loads on masonry are light and the same quality of bearing for concrete in not required. Often stuff empty masonry cement bags into the cores to keep the grout from falling to the bottom. The beam bearing is still located where it is required and does not necessarily line up with the masonry course.

Dik

 

[dhengr]

Gopher13:
Details 1 & 3 are most likely to be done unless you specifically detail, with copious notes, another method of application, such as Hokie suggests. I would set the plate back from the edge of the conc. blk. edge by .5 - .75", otherwise the way the pl. is loaded tends to cause the edge of the blk. to spall. I’ve never liked wet setting of bearings pls. or anchor bolts because the process leaves such a crappy condition under the pl. and around the a.b’s. Half the time there are voids left where the a.b. was pushed in, so it has inferior bond, bearing, pull out strength, etc. etc. There are likely voids under the bearing pl. too. I’ve seem them where it looked almost like they formed a void down to the J-hook or stud head. If they set them in wet enough conc. and then consolidate around them immediately, there is a chance. But, you better be standing there to force them to do the consolidation and re-leveling, etc.

 

[Gopher13]

Great info. everyone. Much appreciated. Thank you!

Kootk: My most favorite engineer that I used to work with shares the same disdain for masonry as you. He refers to it as poor quality pre-cracked concrete.

 

[JLNJ]

I have used #2 for a continuous 5" wide plate where the roof deck runs over top of a wall and I want to weld or shoot the deck to something. I rely on the mason to set it wet and tap it down to the correct elevation.

 

[mbullism]

I've found that no matter how I show it I always get it wrong, lol

Analog spoken here...

 

[OldBldgGuy]

Hokie66 is obviously in a different country than some of us. Option 1 is most common here, but as others have said, option 3 gets used if the coursing doesn't work to the necessary heights (not cut just for plate thickness). I can say I've never used or seen option 2 done in 40 years in both design and construction.

 

[slickdeals]

Would echo the sentiments above. For anything that requires a reasonable degree of precision, I have specified threaded rods to be installed into the top of masonry (with enough lap with vertical reinforcement that is hooked into the bond beam). This allow for proper consolidation of the grout around the anchor rods.

You can then call for a plate with leveling nuts and a non-shrink grout below the plate. This gives contractors the most flexibility in terms of ensuring that the steel framing can be installed correctly.