Multi-wythe masonry wall again

[JStructsteel]

Looking at a building tomorrow that the client wants to open up a wall with a window. He's reported its 2 wythe outside, air gap, then inner wythe wall. Was wondering a few options to open it up.

First option is cut in a groove for an angle, and slide in. Question on this is what stops the wall dropping when they cut the groove? I get arching action, but locally could bricks slide down?

Other is to do a clamping type beam each side, but with the air gap, could cause failure if tightened too much.

I guess option one is the best, what is worry some is the inside wythe, what collects that load? The header bricks? Cut the groove below those?

The client is looking for me to be the expert, but in reality, isnt this the contractors issue, I am just giving suggested construction methods?

 

[RPGs]

If you have enough continuous coursing above and around the opening to guarantee arching action, I would have them pull out the veneer side for access, grind in two angles on inside/outside to support the double outer wythes, thru bolt those angles together, and then add in a separate loose angle for the inner veneer. The exposed angle and bolts will need proper waterproofing, flashing, etc, but you can probably put this on the contractor to figure out. I always spec a triple epoxy coating on steel in contact with masonry.

Under the section that is arching, yes the bricks are hanging in place via magic--usually OK for hanging sections ~3 ft wide or less depending on the condition of the masonry and other factors. Any larger or there's an obvious lack of continuous coursing above/around the opening and I call out needle beams by others. Either way all construction means, methods, procedures, and temporary shoring shall be the responsibility of the contractor.

I wouldn't do a squeeze channel for the entire wall section with the air gap.

 

[XR250]

Does the customer want to see the vertical leg of the angle? Most of mine don't so it is either 3 angles or a beam and plate. Usually, they just cut the opening and install the lintel without any shoring.

 

[JStructsteel]

RPGs - thanks, Good idea on starting on the inside. I dont actually know the span of the new opening yet, so will know that tomorrow. I'm assuming its bigger than 3' though.

XR250, not sure on the final look of the opening. If need be, they can insert a place with stiffeners after the angles are installed, then cut the vertical let off the angle.

I am not sure just saying cut the opening is the best advice. That does not seem to be the procedure people suggest here.

 

[structSU10]

Big question is whether it is load bearing or not. Make sure to see how the floor is supported above the opening.

If it is load bearing I would think needle beams, remove the masonry, install lintel and rebuild to conceal it all. Otherwise it really depends on the span you are dealing with.

 

[dik]

If it's a concern and/or the opening is large, you can install a 'needle beam' to provide temporary support for the wall over the opening.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[jerseyshore]

I don't think many engineers say it's okay to just cut an opening, but that's what happens a lot of the time. Just that magic keeping the masonry up.

 

[JStructsteel]

Back on this, attached is a detail I am working on.

Is it expected that the angle is cut into the brick, but not cut all the way thru until the angle is installed? What keeps the brick from falling out before the angle is installed?

I figure leave a inch of brick, install the angle, then chip away the rest.

Eventually I will show a couple plates welded to close it all off.

Thoughts? [URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1684433834/tips/Masonry_Angle_d7fo5u.pdf[/url]

 

[phamENG]

I don't like that detail at all. Yes, you can flash that, but it's not going to look good at all. And if they mess it up, this whole thing is going to rust and explode the brick wall.

My approach would be to use needle beams over the opening, and then remove bricks 8-12" wider than the opening needs to be removing whole bricks (do not cut them) and at least one course higher than the top of whatever your lintel will be.

Rebuild the jambs up to lintel bearing, any bricks that have to be cut should have the cut side turned into the wall so it's sealed and less susceptible to moisture gain. Install the lintels. I would reverse the direction of each of the angles you have shown. Then rebuild the brick up tight to the existing.

As for what's holding the brick up, I'll quote KootK's old signature line:

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

Mortar isn't there for looks (though a properly tooled joint is mighty pretty). It has strength, and that's what holds the bricks up in between. If the joints are questionable above this opening, then you may need to reconsider (or fix the joints first).

Edit: galvanize the angles! Epoxy is great if handled properly and not exposed to sunlight, but most masons are anything but gentle, especially with things that aren't masonry. Scratch that epoxy and it'll rust all the same and the oxide jacking will be devastating.

 

[GeorgeTheCivilEngineer]

Space the needle beams correctly and corbelling (not just arching) of the bricks will keep them in place. The one or two bricks that are still able to drop can be simply removed or held in place with small timber props.

Sliding angles in is an odd method to my eyes and very vulnerable to mortar blobs and miscoursed masonry (esp in the inner brickwork) ruining the builder's day - needle beams and a set of lintels all the way.

 

[structSU10]

I agree with Pham & George. Additionally I have no clue how they would install the brick that is within the cavity between the veneer wythe and double wythes.

That type of retrofit lintel only really works when you only need to grab each side, and I usually only use it for partition walls inside a building that are quite small, where the lintels are really just insurance.

 

[JStructsteel]

owner doesnt want to do needle beams.

I agree with Pham & George. Additionally I have no clue how they would install the brick that is within the cavity between the veneer wythe and double wythes.

I dont think they will be installing anymore brick. The air space is there for insulation purposes right?

As for the waterproofing/flashing, owner said he would make it work. Not sure what finishes they will end up with. If they can live with it, I certainly can!

Other option is to use the angle as shown inside the single wythe, then bolted channels each side. That would be a bigger pain to flash

 

[structSU10]

I was just talking about how they would actually install this:

they would need to remove some of the veneer brick up a couple courses to get that in.

 

[phamENG]

owner doesnt want to do needle beams.

They'd better have a really sound reason for this. When owners start trying to dictate details or construction methods, I either explain to them that they are not the engineer or I walk away.

They might be able to live with it, but will the new owner of the building be able to live with it in 3 years when things start going wrong?

 

[JStructsteel]

Thanks. Was thinking about construction sequence and getting the angle in the middle
Time to discuss options again with the owner.

 

[JStructsteel]

Here is my attempt at a needle beam details. I assume the needle beams only need to carry the 45 deg weight of the brick above, like a lintel would?
[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1684700684/tips/Needle_Beams_v1julm.pdf[/url]

 

[dik]

and if the building is old, be careful with the type of mortar and strength.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

It can be, but unless real insulation is used, it's of very limited purpose. The real use of the air space is to prevent moisture from penetrating the wall... check 'rain screen principle'. Even with real insulation, you have an air space to minimise water issues.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[dik]

Depending on the span and loading, I often through bolt channels to the wall to act as a needle beam, picking up the reactions at the end of the channels.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JStructsteel]

Dik, the thru bolt and channels wont work in my mind due to the multi-wythe and air space. Would be worried it would pull the wall inwards to the air space.