Brick Lintel Bolted to Wood Header

[STR04]

I'm searching for information that provides guidance for attaching a steel lintel (bolting) to a wood (mico lam) header for large spans. I searched the IBC & NDS for restrictions but couldn't really find anything. I'm asking because I have a wood framed building with large window openings supporting brick veneer above and would like to keep all headers as wood.

TIA

 

[concretemasonry]

Check on the micro lam to see if it is designed for the extra load and what the restrictions (location and size) on drilling and attachments are. Many are produced just to carry loads over interior openings.

If the height of the brick is substantial enough, the arch action will reduce the load on the lintel.

Flash well!

Dick

 

[youngstructural]

Dick's comment about flashing is very apropo. The biggest problems you're going to face aren't going to be structural; Steel and wood can be made to work composite, even if it can be difficult to pull off correctly (otherwise flinch beams would be impossible!), however the risk of water ingress and rot are very much real. You're going to have to be very careful about your flashing, meet (I would recommend exceeding) any weep hole requirements in your brick, make certain that you acheive the required air gap between veneer and backing wall, etc.

I would talk to an older, experienced Architect. This is one of those situations I will not handle without an Architect's advise. They need us, but we need them too; I think you might have one of those situations.

Good luck,

YS

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[ChipB]

Look at Section 2304.12 in the IBC your area is using. IBC 2006 allows supporting masonry on wood, previous versions pretty much didn't allow it. There were some exceptions, but they weren't applicable often.

If you do use IBC 2006, you need to make sure the top and bottom of your MicroLam is restrained from rotating. I'd figure about 3" from the face of the beam to be added to 1/2 the width of the beam for eccentricity of the brick on a typical situation (1/2" sheating + 1/2" air gap + 2" centerline of brick).

 

[civilperson]

Not worth the headache. Use steel and box with wood to get matching visual effect.

 

[DaveAtkins]

I have done this many times. I recommend lag screws, not bolts. The microllam needs to be limited to a deflection of L/600, so as not to crack the brick veneer. And the microllam needs to be designed for the torsion. At each end of the microllam, you may need to add Simpson straps to tie each face of the microllam to the shoulder studs below, to take out the torsion.

DaveAtkins

 

[COEngineeer]

The microlam is probably at the same elevation as the floor. I dont think torsion would be a concern if the joists run perpendicular to the microlam. If they run parallel, I would put blocking @ 16" o.c.

I rather use thru-bolts instead of lag bolt. Make sure you will have enough surface bearing area for the bolts.

 

[ChipB]

STR04,

You'll need to look at your connection detail and use your engineering judgement on the torsion issue.

I don't think a typical Simpson-type joist seat has a positive enough connection into the upper-third of the joist to resist rotation. It would place the nails in withdrawal on a typical seat.

Also, as you stated "large span," the bottom of the joist may be near to the center of the LVL, as it would likely be a 16 or 18.

Personally, I'm with civilperson. I have never (knowingly) supported brick veneer with a wood member. I've always sized the angle to support the brick. You have to be careful about bearing pressure on the masonry.

 

[MikeE55]

A word of caution - I inspected a home where the brick angle was lag screwed into the wood header. The screws were closely spaced, and about 2" above the bottom of the header. The bottom 2" of the header split and collapsed along with the angle and the brick. I don't use wood to support masonry.

 

[mbullism]

"Look at Section 2304.12 in the IBC your area is using. IBC 2006 allows supporting masonry on wood, previous versions pretty much didn't allow it. There were some exceptions, but they weren't applicable often."

Here in MA wood is a no-no... the only exception is for glass block. We don't use it because we can't, but I'm not sure I would if we could.

.02

 

[csd72]

Personally I would never use timber to support the permanent weight of brickwork.

Under a sustained permanent load such as this creep is at its worst case, over time the timber will most likely deflect more than the code calculation gives.

Can you design the steel angle to take the full vertical load and provide blocking/bridging back to the floor beam to provide lateral restraint and take out the twist?

 

[Whodapookie]

Funny, In the South, most brick homes are designed using the wood members (usually LVL, LSL, or PSL) to support the brick lintel that is almost always a L6x4x5/16. The Northern Virgina market and North never allow wood to support the brick. I would prefer for the lintel to be designed to carry the brick load, but it is up to the developer to specify the material they prefer if the code does not address the issue.

For residential construction, I don't think creep is that large of an issue since the "arching action" of the brick will take over once the morter has cured and there are no control joints in the brick. Torsion is usually not considered although maybe it should be. The wood beam should be braced with a king stud on each end as a bare minimum. Most failures from this are ususally from workmanship and poor detailing of the connection of the lintel to the wood beam.

Although this does not mention brick per se, this is a good article for dropped beam headers that may be the cause of issues with wood beams supporting brick.

http://www.i-joist.org/pdf/WIJMA Dropped Header Design Guide (1-3-06).pdf

 

[Chedim]

yes

 

[frogit22]

I feel it is poor practice at best.

Around here it is not allowed for commercial work (IBC). I believe it is allowed for residential (IRC)

 

[csd72]

Whodapookie,

RE:

"....but it is up to the developer to specify the material they prefer if the code does not address the issue."

If this did go to court, this statement would not hold water. You as the engineer are the only one who 'should know better' if the code doesnt specifically cover the situation.

regards


csd