Is adding a bond beam into an existing CMU wall fesible? 2

[reverbz]

Hey Guys,

So I know adding vertical reinforcement and grout into an existing CMU wall is doable, but how about a bond beam with horizontal reinforcement? Is this doable? Seems like it would be difficult.

thank you!

 

[jayrod12]

In the middle of the wall, or at the top? Middle seems unlikely to be constructable without shoring the wall above until the bond beam can be installed, grouted and cured.

At the top of the wall, I don't see a big problem.

 

[reverbz]

@jayrod12 I'd be thinking about a wall with a parapet so it would be a bearing line below so technically middle. Any way to add bearing in this area? Do you just span a ledger between verticals if you're trying to bear new trusses/joists?

 

[jayrod12]

@jayrod12 I'd be thinking about a wall with a parapet so it would be a bearing line below so technically middle. Any way to add bearing in this area? Do you just span a ledger between verticals if you're trying to bear new trusses/joists?

Yeah, I don't see why you couldn't just mount a ledger to the face of the wall unless your loads are extremely high. And in that case, a little bit of demo to support heavier loads would be anticipated.

 

[milkshakelake]

If it's a wall with a parapet, I think it's cheaper to remove the parapet and install bond beam. If you don't want to do that, I'd look into alternative methods of supporting new trusses, like an interior structural backup wall.

 

[milkshakelake]

Sorry just saw the comment about the ledger. This can work but you have to consider the eccentric moment going into the wall, as well as local tension to prevent "pullout" of the joist.

 

[reverbz]

@milkshakelake thanks, just confirming you mean spanning between the verticals right? Wouldn't the local tension be present in a bond beam connection as well or am I missing something?

 

[KootK]

thanks, just confirming you mean spanning between the verticals right?

I wouldn't sweat the business of spanning between verticals. I could see it being a nightmare trying coordinate the fastening for that and I doubt that it's necessary. I'd be inclined to make it work with fastening to the unground cells or not at all.

Was your original plan to create new bearing pockets for the joists over the bond beam?

 

[KootK]

I've used this detail before with OWSJ and felt decently about it. If it's top chord bearing trusses, the channel hides nicely within their depth.

 

[milkshakelake]

@milkshakelake thanks, just confirming you mean spanning between the verticals right? Wouldn't the local tension be present in a bond beam connection as well or am I missing something?

I'm not sure what you mean by spanning between verticals. But yes, tension would also be present in a bond beam connection and would need to be addressed somehow. It should be relatively easy to handle. I mean don't just put a ledger and sit joists on top of it without a decent tension connection to the wall. I haven't seen that, but I've seen people do joist pockets without tying the joist to the wall, which leads to all kinds of issues. So it's merely something to be aware of, rather than something that would change your design.