Who Owns the Backing Design? Why This Overlooked Scope Matters
- Matthew Elgersma, P.Eng., P.E.
- 4 days ago
- 7 min read
Backing is one of those small but essential details that can easily be overlooked. On many projects, it’s installed without much attention, but that doesn’t mean it isn’t important. This post highlights what backing is, why it matters, and how clear responsibility helps projects run smoother.
Backing doesn’t get much attention. It’s rarely shown clearly on drawings, and it doesn’t fit neatly into anyone’s scope. The base building engineer typically doesn’t cover it. The trade's engineer assumes it’s by others. And the general contractor, who often installs it, often doesn’t have design information to work from.
It’s a small piece of the structural puzzle, but when it’s missing, it can sometimes significantly affect the public safety and un-intentionally expose the base building engineer and/or architect to unanticipated risks.
Background
When we talk about backing in structural engineering, we’re referring to the secondary supports that allow finishes, fixtures, or cladding to be safely attached to a building. It’s the unseen structure behind the surface, giving screws, anchors, or bolts something solid to grab onto and also transferring any loads from connected items into other structural elements, like studs.
Backing can be flat stock metal, steel stud tracks, plywood, or lumber, etc. Backing supports things like grab bars, shower seats, wall-mounted equipment, glazing anchors, masonry ties, handrails, and signage. As a funny aside, we've even provided backing drawings for wall mounted clocks on some hospital projects.
The Scope Gap Problem
The scope gap issue arises because each trade hires their own engineer who provides engineered designs and field reviews for the scope of work which their client completes. So the wall and ceiling trade's engineer will review the wall and ceiling framing. The veneer trade's engineer will review the cladding and how it connects to the building. The glazing trade's engineer will review the glazing and how it anchors to the building.
Because general contractors often take care of the backing installation themselves, none of the trade engineers will have provided designs or field reviews for that scope. For a masonry veneer trade engineer, the backing is often installed and covered before their client, the masonry veneer trade, gets started on the project.
If the general contractor installs the backing, and does not have backing details from base building engineer or a specialty engineer which they have retained themselves, the backing often will not be engineered at all.
Where We've Seen the Gap
One of the most common places that backing is not properly designed and reviewed is the backing for brick veneer supports. Brick veneer is often supported on structural steel angles which are bolted into concrete or blocking in the wall. There is usually no issue if the anchors are into concrete, however issues arise when the brick veneer support cannot connect to the concrete. While the brick veneer engineer will typically state what material they are assuming their bolts are going into, they will rarely design the block itself and its connection to the studs. This connection is critical as the loads imposed on the shelf angle by the brick can be very large. In our experience, sometimes the brick veneer trade has this added to our scope late in the project, or the general contractor gets the blocking engineered, or this gets totally missed. Sometimes the base building engineer will have a blocking detail for this in their drawings, but this is the least common outcome in our experience.
Another place where backing is often missed is when steel stud parapets are framed on top of metal deck roofing. In this situation, a strip of plywood is typically installed around the roof perimeter. The trade installing the parapet then connects to that plywood. The issue is that this perimeter plywood is rarely specified in the base building structural drawings or in the trade engineers’ drawings. Once installed, neither the trade engineer nor the base building engineer usually has an opportunity to review it. The trade engineer can sometimes work around this by detailing parapet connectors that fasten directly to the metal deck instead of the plywood, but this isn’t always practical in the field and can be difficult to verify after installation.
Case Example – A Critical Component Caught a Little Late
On one recent project we completed, the glazing system was connected to the base of a steel stud parapet. This is a tricky and very unideal condition, and it only occurred on this project due to a unique set of circumstances. During design, both the glazing and steel stud trades excluded the backing from their scopes, as neither trade was installing the blocking. The general contractor installed the blocking themselves, but no engineered drawings were provided to guide how it should be done.
It wasn’t until after the glazing anchors were installed that the problem came to light. The GC asked who was responsible for the backing design. The glazing engineer said it was outside their contract. The steel stud engineer said the same. The base building engineer didn’t consider it part of their work either, since they found it a little strange for them to provide engineering for a component sandwiched between the glazing and steel stud trades scope.
When the installation was reviewed later, it became clear that while the GC’s approach was typical, it wasn’t structurally acceptable. The 2x wood blocking had been fastened with screws into the end grain, which provides little shear strength. The only way to fix it was to open up the parapets and add 16 ga cold-formed angles and screws.
The repair added cost, time, and frustration for everyone involved. It was a clear reminder that “typical” details aren’t always adequate (in this case the loads were exceptionally large), and that without a defined scope for backing, even common practice can lead to unsafe conditions. Thankfully on this project, the issue was caught and addressed, however there are many projects when this doesn't happen.
Why It Matters – Public Safety and Liability
Not all backing carries the same level of risk. Some items, like clocks or paper towel dispensers, are low impact. If they fall, they might cause inconvenience but not real danger. Generally speaking, these items really don't need to be "engineered".
Other items, such as grab bars, shower seats, masonry anchors, and glazing supports, are much more critical. These components rely on properly designed backing to safely carry the loads they experience in use.
When the responsibility for backing design is unclear, there is a risk that no one checks whether the installation can actually support those loads. This can lead to unsafe conditions that may not be discovered until long after construction is complete, if ever. In some cases, the base building engineer or the architect might become responsible by default as a result of trade engineer's schedules not covering certain scopes. .
Backing might seem like a small detail, but it directly affects public safety. As such, it should be reviewed by professionals.
How to Avoid the Gap
There are really two good ways to handle backing scope gaps.
The first is for the general contractor to retain their own specialty structural engineer. In this setup, the GC installs the backing, and their engineer provides the design drawings and any required field reviews. This keeps the responsibility with the group doing the work and allows the design to reflect the actual materials and methods being used on site. It also avoids the delays that come from waiting on other trades to provide drawings. In our experience, this does not happen much.
The second option is to make it clear in the contract which trade is responsible for the backing. In this case, the general contractor does not install it. Instead, the trade that owns the scope, whether it is glazing, masonry veneer, or steel stud, installs the backing and engages their engineer to provide the design and reviews. This option works well when the responsibility is clearly defined early and everyone understands their role. In our experience, this option happens more often than the first option when the backing scope gap is addressed.
Either approach can work and there are probably many other ways to deal with backing scope. What matters is that the responsibility for both the design and installation of the backing is clearly assigned before construction begins. When that happens, the risk of confusion, rework, and unsafe details drops significantly.
A Quick Reality Check
If you've read this far, we should clarify that it’s worth noting that most projects don’t have major problems with backing, as best we know. In the vast majority of cases, things get built safely, and even when the scope isn’t perfectly defined, the experience of site crews and trades usually keeps everything working as intended.
This article isn’t meant to sound alarmist or suggest that buildings are at risk because of missing backing. The intent is simply to highlight a small but often misunderstood part of coordination that deserves a bit more attention. Backing issues are rare, but when they do occur, they can create unnecessary rework and confusion. A little clarity up front goes a long way toward keeping things simple and safe.
Closing Thoughts
Backing is rarely talked about, but when it’s missed, it can cause real problems. It often sits between scopes, and because of that, it often falls through the cracks. When no one takes ownership, it can create safety risks, added costs, and frustration for everyone on site.
Backing design might not be the most exciting part of a project, but it’s an important one. Getting it right means understanding how the different systems connect and making sure the load path is continuous. When the design, communication, and installation are aligned, the rest of the project goes smoother.