Attaching to existing masonry 2

[NewbieStruct]

I am designing an addition to an existing building. I have situation where I have to connect a deck angle to an existing CMU wall (this wall would be non bearing for the new structure). I have existing brick veneer on the existing wall that the architect does not want to remove. Can attach the deck angle to the existing wall using epoxy anchors or using thru bolts ? The existing CMU wall is fully grouted and I have to transfer about 4.5 k shear load over a length of 50'.

 

[concretemasonry]

A brick veneer is not a structural element and there may even be an air space (as much as 2" including insulation) between the brick and the back-up. You never know what the base anchorage of the brick veneer is and it could be sitting on a steel angle. With this situation, a through bolt to use the grouted block can get quite long and flex or bend, reducing the effective load transfer.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[NewbieStruct]

The brick veneer on the existing building goes all the way down to the foundation. The air space is 1.5". The veneer is 3-5/8"

 

[bookowski]

You are saying that it's not load bearing for the new structure? So is the angle just for edge of deck support during construction? Are you attaching the angle to the brick side of the CMU side?

 

[NewbieStruct]

Yes, the existing CMU wall is not loading bearing for the new structure. The angle is just to support the deck on non bearing side.

 

[bookowski]

And are you attaching to the brick side or the CMU side?

 

[NewbieStruct]

I am attaching to the brick side. The brick is on the exterior of the existing building.

 

[bookowski]

4.5k over 50' isn't much load but I still wouldn't trust brick veneer for transferring loads. If it was just the edge of deck for construction I would say ok, but not for transferring final structural loads.

I would tell the architect that the veneer is not structural and you can't use it to transfer loads. Go back to the base cmu and do your attachment there.

 

[NewbieStruct]

I will be attaching thru the brick veneer to the masonry. The architect does want to tear down the veneer.

 

[MiketheEngineer]

Hilti or Simpson or some other mfg makes a "wedge" type anchor for use in brick - has pretty low values.

Regardless - brick is pretty "lousy" - see if you can get to the grouted CMU - much better results!!!

 

[NewbieStruct]

I will be getting to the grouted CMU but will be passing through the brick veneer. I was just wondering if that (passing through brick veneer) to reach the grouted CMU is an issue.

 

[bookowski]

Yes, I would say it's an issue. You will need the anchors to cantilever about 5"-6" (brick + airspace). This anchors would need to be designed for bending in the anchor but also the masonry needs to be designed to take that additional force. How will you connect the angle to the anchor, you can't torque the bolt down since you have the airspace. You are dealing with relatively small loads so you may be able to show that it works - going to be a funky detail though.

 

[msquared48]

I would install specially designed periodic brackets directly to the CMU, say 6 to 8 feet on center for example, and run the angle outside of the brick veneer, attached to the brackets.

Bo not bear on the veneer!!!!!!!!!!!!!!!!!!!!!!

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[hokie66]

A section would help. Is the deck near the ground (near bottom of the cavity) or elevated? I wouldn't necessarily discount bearing on brick, if the brick is limited in height.

 

[NewbieStruct]

The existing brick veneer continues above the roof of the new building.

The existing masonry wall is 22' tall with no openings. The new deck is going to be at 8' height.

 

[DST148]

Assuming not in a very high seismic and wind zones.....
Adhered veneer (noncomposite wythes) relies on the back up for out-of-plane loads only. Veneer bearing on the foundation wall is typically isolated from the back up structure vertically and laterally (in the plane of the veneer) and assumed to be self supporting for loads in the plane of the veneer. Given the small magnitudes of lateral loads, and no net tension on the veneer at the foundation level due to these additional lateral loads, the loads may be transferred via anchors in the veneer only and not through through-anchors to the CMU back-up.

 

[dhengr]

I agree with Hokie, the brick could likely carry the 90lb./l.ft. vertical load from the deck, but there are plenty of questions before I would allow this. And, a sketch/section showing the entire wall would clear up some of these. What kind of deck is this that only has a 90lb./l.ft. reaction at the bldg. wall, can’t be much load on it, or much of a span. Is the deck conc. or steel that it uses a ledger angle, or is it wood construction? But, we’re always kept in the dark on these important issues. 90lbs./l.ft. is only a little better than 2' height of the brick veneer. I want to see an adequate brick ledge at the found. I want to see how the brick is tied laterally to the grouted CMU wall.

The IRC in the U.S. prohibits this. I don’t think the IBC out-and-out prohibits it, but it probably discourages it, and says it needs special engineering attention. The veneer can carry the vert. load, but needs shelf angles periodically in height. Remember, brick tends to grow in size while concrete or CMU’s tend to shrink. The veneer can take some lateral load in plane. But, there should be no load perpendicular to the plane of the wall, or relative movement induced by the deck on the brick veneer wall. I would not attach a deck just to the brick veneer (to the veneer alone) because of the potential of lateral loads on the veneer.

 

[hokie66]

Thanks, dhengr. You read my mind, as usual.

 

[bookowski]

I thought he was saying that needed to transfer 4.5k of lateral load to the wall. The original post says that is is a non load bearing condition. I think he is saying that the wall is picking up the edge of a metal deck, parallel to the deck span, and he is counting on it for lateral resistance (i'm doing a lot of interpreting though so maybe I'm off)

 

[dhengr]

Bookowski:
Upon rereading, and I had already read it several times, you certainly might be right. The “4.5 k shear load over a length of 50'” reads better your way, than as a vert. load. I still might put that 90lbs./l.ft. into the plane of the wall if I had test prisms of some of that veneer brick/mortar lay-up; and had been able to design for it btwn. the veneer and the CMU wall. But, I think on existing brick veneer I would put that into the grouted CMU wall through some specially designed shear brackets. I do not want this loading to impart a load perpendicular to the plane of the veneer. This would involve removing 6-10 bricks at 6 or 7 locations and then partially replacing the brick around the brackets, with flashing, caulking, etc.