Awning Attachment to Facade

[BSchwab]

I have a project where the customer would like to add an awning above a couple of the doorways. Approximate size is 4' wide (perpendicular to building) and 8' long (parallel to building). The wall system is a metal stud backing to a 4" split face CMU facade. Minimum horizontal joint reinforcing and ties appear to be provided. The question is, would it be possible to attach this awning to the building by just anchoring to the 4" CMU? Or is a more substantial method needed? Perhaps some sort of anchoring into the studs. It is preferable to only use the facade because then the inside would not need to be torn up.

I have done some calcs, and with anchors at 1'-0" oc, each needs to resist 170 lb of pullout in addition to 140 lb of shear. It seems like it might work (I still have to do some more checks), but I have never design anything like this before. So I was hoping to hear about what other people thought. Thanks!

 

[Ron]

Not sure of your location, but you have to consider snow loads with drift (overhang condition) and wind loads (overhang condition).

4" split face CMU is usually insufficient to handle much of any structural reaction. In this case, I would go through the CMU and anchor to the structural portion of the wall....yes, you'll have to reinforce the wall and you'll need to tear up stuff on the inside for access, but that's the proper way to do it....after all, you wouldn't want the canopy to come down during a snow event and prevent egress..your liability could be quite high if that happened.

I've designed hundreds of canopies, including hanging canopies such as the one you've described as an awning. In each case of a hanging canopy, the anchorage is the controlling factor.

 

[MiketheEngineer]

I have to agree with Ron..

However if the wall is sheathed with something you can identify like plywood - you might get by with toggle or multiple toggle bots located near a stud.

These can be nasty and some fly-by-nights just anchor them to anything!!??

 

[engineertipsman]

Just had a hotel in town where one fell down, and brought brick with it...over a door, no one injured. These are the money makers for lawyers

 

[hokie66]

No cantilevered structural element should be anchored into masonry veneer. At least once a year, I read about a kid being injured or killed because a basketball backboard has been supported on brick veneer.

 

[BSchwab]

Thanks for all the replies. Seems like everyone agrees that this is a bad idea. I figured that was the case... but I also thought that it must have some capacity. So I started to try to calculate the capacity. However, it quickly became a nightmare with all of the different checks that I thought needed to be done.

Ron, you mentioned that "4" split face CMU is usually insufficient to handle much of any structural reaction". Does this include the vertical reaction or were you just talking about resisting the moment? For example, if we were to add columns on the free edge, the veneer would only be taking a vertical load (approximately 140 lb/anchor). While this solution isn't ideal for the customer, who knows, they may like it better than tearing up their interior.

Thank you guys for the safety warning... the last thing I want is for anyone to be injured.

 

[Ron]

BSchwab...it can take vertical loads, including the shear from anchors, though not to the same degree you would get with structural masonry. It is not good at resisting tension in anchors nor the force couple you would get from a hanging canopy.

 

[a2mfk]

Agree with everyone- don't anchor into 4" CMU, its cladding.

I would look for a canopy solution that is self supporting, perhaps a couple of small HSS columns placed close to the building on their own small footings, extend up as cantilevers to pick up a right-triangle framed mini-truss to form your canopy structure. Then dress it up to match the existing structure. Sounds pricey I know for a couple of small awnings over doors.

 

[csd72]

Brick walls are great for vertical loads but not much good for anything else.

There was an earthquake in Newcastle in Australia where many many canopies that were tied back to 4 inch masonry walls pulled out even though the rest of the canopy was perfectly fine.

In masonry veneer the studs are the structural element - use them.

 

[BSchwab]

I just found out that the wall construction is made out of 2x6 wood studs with a structural sheathing instead of the 6" metal studs. Somehow I didn't get the correct information the first time...

In addition, there is a double top plate connected directly to the wall and second level floor trusses. So it looks like we can anchor into that through the veneer if we hang this high enough. I'm sure they'll have fun hitting the wall plate.

Otherwise, we'll have to go with the column approach.