Stone Veneer vs Angle Ledger

[bigmig]

I have been asked to comment on a condition where a mason installed a stone veneer in a manner so that the actual stone is proud of the angle ledger.
SEE ATTACHED PHOTO.

My first impression is that the stone is attached via adhesion to the mortar....a pretty nebulous concept. I was planning on rejecting this, but would like
to back it up with some code reference.

Does anyone have some recommendations on where to start in terms of masonry code?

The project is US Based.

Thanks.

 

[jike]

Leger horizontal leg does not look long enough. Where are the ties to the backup?

Check the drawings and check the spec before deciding who is responsible.

 

[hokie66]

Like any masonry veneer, the stone must be tied to the structural wall with horizontal ties, similar to brick ties. Just sitting on the angle does not accomplish that. The angle does appear to be a bit small.

For stone veneer details and specifications, suggest referral to the Indiana Limestone Association.

 

[XR250]

Seems sketchy to me. I always use 6x6 angles for this. Are there any brick ties or is it just bonded to the tar paper?

 

[jdgengineer]

Chapter 6 of ACI 530 provides masonry veneer design requirements. As the veneer is quite thick you will exceed the limitations of "adhered" and will need to follow provisions of anchored veneer. As hokie mentioned you will need brick ties installed per the prescriptive requirements at the very least.

For the lintel sizing we prefer to keep the lintel 1/2" short of the outside edge of the veneer to provide nearly full bearing (this works great with 4" veneer & 3 1/2" lintel). With other size veneer it doesn't always work out with standard size angles. We try and keep at lease 75% of the veneer supported with the angle. I'm not sure if there is a specific code requirement, but any less than that and I have felt uncomfortable.

 

[calvinandhobbes10]

Use ties and an extended horizontal shelf (stitch weld a cont 1/4x6 galv plate) for the remainder of the wall.
I don't think the portion already built is going anywhere. Some post-installed anchors could give redundancy.
This close to grade, I'm surprised a steel shelf was used over a concrete ledge or footing bearing. Paint the shelf with coal tar for corrosion protection if it won't be covered adequately.

 

[bigmig]

The IBC Section 1405 is specific in terms of masonry ties....2 square feet of veneer per tie. The Building Code Requirements and Specification for Masonry Structures leaves it open ended in an effort to facilitate "creative" ways to attach masonry. They actually state this. They do point out that you loads need to be transferred via principles of mechanics.

There is no way we are welding galvanized steel onto this. You can't reach it to weld it, you can't safely weld galvi without poisoning your welder, you burn off all the galvanization while welding,
you need a special inspection, you then need to repaint the galvi. No way is that a practical cost effective solution, no personal disrespect intended.

The reason we do steel angles, even sub-grade is because they are cheaper than concrete ledgers, and install when you need them...which is right before veneer arrives.
Most concrete companies will batch a minimum 1 or 2 yard mix, which is more than we would need to pour ledgers. In addition, you have to time them with your backfill process.
I used to believe strongly in never burying steel until someone pointed out to me that the rate of decay of sub-grade steel, at least in most soils in my area, is something
like 85 years until the bolts or angles are turned to rusted dust.


Regarding the ties, this is seldom specified by engineer or architect, yet I have personally inspected projects where the stone had cracked and fallen out because the mason didn't use any ties. Do you guys spec tie spacing, type and size on your drawings for residential stone veneer?

 

[calvinandhobbes10]

Valid and interesting points about the steel. Rec'd bearing width is 2/3 of the masonry width, so that's the challenge.

ACI530 section 6.2.1 (and 1.3) sounds like an effort to promote adding new proprietary products into designs quickly, as opposed to delays or Code-extrapolations while the Code gets updated (commentary on section 1.3). It indicates board reviews and test data, which is certainly not the need here. I suppose this section can also be construed as a means of resolving CA issues by showing stresses, loads and calcs to justify a greater anchor spacing than 6.2.2.5.6 prescribes. I again would lean toward anchoring the remaining part of the wall and leaving the as-constructed segment as is.

 

[calvinandhobbes10]

Also, I don't spec ties or spacings. I usually do a redline of the architect's spec on commercial jobs for structural criteria, and rarely change the veneer tie section.

For residential veneer (brick, stone, either), with no specs, if I come across any reference to the ties, it's usually a callout on an arch section "ties at 16" o/c ew" and rarely do I have any comment. This usually goes without issue, but certainly could be improved.

 

[XR250]

Regarding the ties, this is seldom specified by engineer or architect, yet I have personally inspected projects where the stone had cracked and fallen out because the mason didn't use any ties. Do you guys spec tie spacing, type and size on your drawings for residential stone veneer?

I never do and it probably would not make a difference.
Many jobs I go to from the 60's and 70's do not have ties and simply use the soffit trim to keep it plumb - geez.

 

[bigmig]

I inspected a house with veneer failure. The mortar had cracked and the stones were randomly falling out. We pulled the entire thing off.
Not one tie. Everything else was to code. We did not run any testing on mortar, so in hind site, that could have been a contributor.

So in my personal experience, the ties make a big difference. They appear to basically keep things from moving 'just enough' that the cracks can't develop.
Also, in further reading of the IBC Section 1405.7, ties need to have 15 inches (!!) of embedment into stone mortar joints. The tiny corrugated galvi
ties I typically see are about 3" long. Curious how trades "wander" from code without anyone really catching it.

 

[XR250]

When I said "it would not make a difference" I meant that they may or may not get installed depending on the contractor, mason or if things get inspected.
It is an item that typically gets installed while the masonry is going up (at least in residential) so unless the inspector is standing there the entire time, how is anyone going to know?
Of course they make a difference structurally.