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Loose Lintel for Brick Veneer

Loose Lintel for Brick Veneer

Loose Lintel for Brick Veneer

(OP)
I am having a few issues with the loose lintels on a building project. The architect is showing 6" metal studs + 5/8" sheathing + 2" Rigid Insulation + 1 1/2" air space + brick veneer. This means that the total distance from outside face of sheathing to outside face of brick is 7 1/8". This leaves me with the need to update my lintel schedule on the job. I have sized a L7x4x3/8 lintel on a maximum opening width of 5'-0".

Limiting the deflection to L/600 and tip rotation to 1/16", I am finding that this L7x4 is right at it's limit. I'll have to have the architect move his joints off of the edges of the windows to ensure full arching action.

I am fortunate that I don't have any larger openings on this metal stud back-up.

My question is this: Have any of you encountered a similar condition? (This is the largest cavity I've seen. The architect tells me the new energy codes are driving this.) If so, are you moving away from loose lintels?

Thank you for your time and help.

RE: Loose Lintel for Brick Veneer

I would have thought a 4x4x1/4 L would have been more than adequate for a 5' span. Why are you making it 7" wide?

BA

RE: Loose Lintel for Brick Veneer

(OP)
The architect wants the vertical leg against the sheathing - which is a condition we have been seeing at our firm a lot in the past 5 years.

I think the reason has something to do with flashing.

RE: Loose Lintel for Brick Veneer

I thought that the cavity behind a rainscreen was supposed to be vented top and bottom. The architect is cutting off air circulation with his detail.

BA

RE: Loose Lintel for Brick Veneer

I would never support brick on the end of a 7" leg. You need to be concerned about the structural aspects of the building more than the architectural.

RE: Loose Lintel for Brick Veneer

And what would be wrong with placing the required insulation between the metal studs?

Batt insulation would work well here...

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

RE: Loose Lintel for Brick Veneer

(OP)
As stated in original post, I have checked stress, deflection, and toe displacement due to rotation.

I am no expert on this part, but Current energy codes apparently require a certain amount of continuous insulation in addition to the batt insulation.

My primary question was whether or not you are seeing these types of details and finding them just as restrictive. I have seen these details on jobs for years now... though not quite as extreme as this. I have also compared our details to those of peers on several occasions... when the opportunities present themselves. Again, those situations were also a bit less extreme than the one I am describing.

RE: Loose Lintel for Brick Veneer

I have not run into this situation before, but...

I would use a tube steel section as the window/door header within the studwall, perhaps with tube steel columns at the ends, then weld the ledger of the size needed to the tube steel header. The tube steel section is great for torsion...

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

RE: Loose Lintel for Brick Veneer

Couldn't you have the fabricator weld a plate to the backside of a smaller angle?

RE: Loose Lintel for Brick Veneer

Hey hokie66....AMEN

As we all know, architects make it pretty....we make it work.

RE: Loose Lintel for Brick Veneer

Ron,

Rather: Architects provide the template for asserting efficient form and vernacular to impress the human response into a view of the emerging tectonic visualization and the effects of materiality on praxis.

Engineers make it work.

RE: Loose Lintel for Brick Veneer

I agree with BA's comment - this seems like a bad architectural detail. If the reason is energy code it seems counter-productive to disrupt the rigid insulation with the angle, a thermal bridge, not to mention the disruption of the cavity drainage plane.

Also, how do you check tip rotation? Maybe I'm off here but with the angle so offset the end bearing will only be at the outside of the legs, the vertical will be hanging out in space - not much torsional restraint there.

RE: Loose Lintel for Brick Veneer

I actually Have a project going now with a 7 3/8" cavity. We needed a relieving angle to pick up 3 stories of brick we ended up with a L8x7x3/4" angle (from memory i don't have the plans in front of me) We have wood stud walls, so ended up putting steel columns in to support the lintels. The cavity was done mainly to get the insulation in as you noted.

RE: Loose Lintel for Brick Veneer

I don't get it either. The ones I have worked on had the insulation run up behind the brick.
FWIW, I think in most situations, the lintel just acts as formwork until the mortar cures and then the brick acts as a deep beam. I know we don't design as such, but I think this represents reality. Otherwise, we would see many more issues with brick veneer over large openings. One thing you can do is specify joint reinforcing in the first couple of courses of brick which tends to make it act like a reinforced masonry beam. I heard this from an engineer at the Brick Institute of America.

RE: Loose Lintel for Brick Veneer

(OP)
bookowski,

I've modeled it several ways. I started with a beam model. Then I worked up a quick solid model in Femap/Nastran so that I could measure the tip deflection relative to the deflection at the vertical leg. I only constrained the part of the angle that would be embedded in masonry on each side of the opening.

RE: Loose Lintel for Brick Veneer

The wall construction isn't bad... can be supplemented with batt insulation. Bad overall detail.

The loose lintel is the problem and it shouldn't pass throught the rigid insulation to the sheathing. In these environs, the angle against the sheathing could easily be at a temperature of -30C... As BA noted, it should be bearing on the ends of the adjacent veneer and his L4x4x1/4 would likely be OK.

Dik

RE: Loose Lintel for Brick Veneer

The steel stud (wrinkled tin) is the major factor in the thermal short-circuiting compared to the lintel. The studs can reduce the FG theoretical wall "R-Value" by 50%, which is the major factor and is not important to structural concerns.

If you have gravity concerns. brace the lintel for a short period to allow the real load on the lintel be reduced by the structural properties of the masonry above., but I defy anyone to calculate the exact amount.

Going 2 stories between relieving angles is common, but going 3 or more creates problems creep/expansion with long term deflection of different materials (steel vs clay), but that is really an architects problem to control cracks and window leaks/alignment.

Dick

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

RE: Loose Lintel for Brick Veneer

I strongly suspect that what the architect REALLY wants is to have a member closing off the cavity above the windows. We locate our steel lintel angles with approximately 3/4" clearance to the back of the brick (that provides adequate clearance for the flashing) and weld a piece of continuous flat bar or a small continuous angle to the back of the lintel angle to close off the cavity. This detail works structurally and makes the architect happy.

RE: Loose Lintel for Brick Veneer

From what I know ASHRAE 90.1 is driving this whole issue. It is incorporated into the IBC by reference. This standard now provides minimum continuous insulation values as well as a total insulation value. It looks like the majority of the time you will need both cavity and continuous insulation.

I have dealt with this on one project to date, but it looks like that was just the beginning.

RE: Loose Lintel for Brick Veneer

Hello there, I also have a question regarding loose lintel. AS this thread is about the same topic, I am adding my question here as well.
We have multiple window openings spaced 1ft apart ( 4-5 ft wide windows opening size). My concern is:1 ft wide available brick wall support will act sufficiently for the bearing load?.
Any thoughts appreciated.

RE: Loose Lintel for Brick Veneer

It might... depends on how much brick over... also as a veneer, it has to be suitably anchored to whatever backing is available.

Dik

RE: Loose Lintel for Brick Veneer

If the lintels bear 4" at each end, there would be only 4" between lintels. I think I would want to anchor the end of each lintel to the brick below as well as the backing.

BA

RE: Loose Lintel for Brick Veneer

The brick veneer above the window is 12ft high.And this is cold formed stud load bearing wall system. Definitely, the veneer will be anchored for wind load on back up but now I am concerned about vertical load of brick.
As the window openings are about 6 ft wide, I have jamb studs on every 6ft.
I see one of my option as attaching shelf angle to window header studs. Another option attaching only to jamb studs and spanning between jamb.As not much experience on light gage design system.

As Both of you Dik and BA mentioned about anchoring to back up system- do you guys means anchoring the lintel angle to jamb and header. Little more about anchoring types/details would help me alots.
thanks

RE: Loose Lintel for Brick Veneer

This is done commonly around here without incident (that I have ever seen). Since the brick column is anchored every 24" (typically), Euler buckling usually is not an issue so it really comes down to the compressive strength of the brick - which is pretty darn high.
Trying to use the studs to support the lintel is a waste of time IMHO (I am a light gage designer) The light gage system is typically much more flexible than the brick in a vertical sense due to track to stud tolerances etc. Also, the brick may grow over time due to moisture absorbsion so the lintel may possibly want to pick up the framing at some point.

RE: Loose Lintel for Brick Veneer

I wouldn't want all that brick supported on 12" long sections of brick. Neither would I want it supported on light gauge studs. I think you need structural steel jambs, providing support for shelf angles rather than loose lintels.

RE: Loose Lintel for Brick Veneer

The brick veneer is not capable of resisting wind loads by itself. The backup system, which in this case is light gauge steel framing must be designed to resist wind. The brick pier and steel lintel must be anchored (laterally but not vertically) to the wind resisting structure, otherwise the veneer is unstable.

The brick pier is carrying a 12'x7' area of brick. At 40 psf, that would be 3360# which results in an average bearing of about 70 psi on the brick pier. That should be no problem for the pier provided it is laterally braced.

BA

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