Connections & installation
Slotted Holes and Movement Connections in Steel
Understand why slotted holes appear in steel details, distinguish adjustment from movement, and coordinate fasteners and adjacent finishes correctly.
Find out why the slot is there
An elongated hole may serve a fabrication, erection, adjustment, or movement purpose. Do not infer its function from shape alone. Locate the approved detail and identify whether the connection is intended to remain fixed after installation or to accommodate relative movement in service.
Write that purpose beside the connection reference in the coordination record. A simple statement such as vertical movement detail is useful only when it points to a specific accepted assembly. Keep direction, location, and product identity together so the field team does not apply the instruction to another nearby slotted connection.
References: 2025 Specification for Structural Joints Using High-Strength Bolts (PDF) · Slide-clip and head-of-wall example details (PDF)
Separate structural bolting from slide-clip details
The RCSC specification addresses slotted-hole conditions within high-strength bolted joints. Manufacturer slide-clip details describe a different type of assembly, with their own fasteners and installation geometry. Rules from one system should not be copied into the other.
For example, Simpson Strong-Tie's published slide-clip drawings identify particular shouldered screws and locations within the slots for those illustrated products. This illustrates the need for exact product instructions; it is not a universal instruction for every clip, slot, or steel connection.
References: 2025 Specification for Structural Joints Using High-Strength Bolts (PDF) · Slide-clip and head-of-wall example details (PDF)
Coordinate the details that can stop movement
Review the complete assembly and nearby work. A movement detail needs coordination beyond the visible slot.
| Item | Question to resolve | Reference |
|---|---|---|
| Connection purpose | Fixed after adjustment or intended to move? | Approved design detail |
| Direction | Which relative movement does the assembly address? | Movement requirement and product detail |
| Fastener arrangement | Which exact product and placement are specified? | Manufacturer installation information |
| Adjacent finishes | Could nearby work obstruct the intended action? | Coordinated architectural and trade details |
| Inspection timing | When can the assembled condition still be seen? | Project inspection plan |
Do not fill unused openings by habit
A hole or slot can look unfinished to someone accustomed to fixed connections. Before adding a screw, welding an opening, or restraining a member, verify what the detail requires. More attachment is not automatically more correct when the intended behavior includes relative movement.
Make that requirement visible in the trade handoff. Identify the affected locations and attach the accepted detail. A general instruction to allow movement may be missed when a later installer sees an apparent gap. A location-based coordination note gives the team something concrete to check before the assembly is covered.
Example: finishing work near a head-of-wall detail
Suppose a wall has an approved movement connection at its top. Before finishes conceal it, coordinate the framing, finish, and any associated joint-system details. Record how each trade's work relates to the intended movement rather than assuming that the framing clip alone resolves every interface.
If a field observation shows an additional attachment that is not on the detail, document it and obtain a disposition. The correction should come from the responsible review, with any required follow-up inspection. Do not remove a questionable item without understanding what work or temporary condition depends on it.
- Confirm the exact connection purpose and direction.
- Use the named clip or bolted-joint requirements.
- Coordinate adjacent work before concealment.
- Record and resolve changes to the intended assembly.
Retain the movement requirement for maintenance
A movement connection can become harder to recognize after construction. Include the accepted detail and location information in the closeout record, especially where later maintenance may add supports, trim, or equipment nearby. The record should explain the intended function without inventing a movement allowance. Future work can then refer back to the responsible design information before bridging a gap or adding an attachment that changes the assembly.
Common questions
Does every slotted hole allow the member to slide?
No. Slots have different purposes, and some connections are fixed after adjustment. Determine the intended behavior from the approved detail.
Can I enlarge a round hole to make a movement slot?
That is a connection modification requiring appropriate design and fabrication review. Do not create an improvised movement detail in the field.
Sources & further reading
Use the current documentation for the exact product and project. Source links do not imply a partnership or endorsement.
- Slide-clip and head-of-wall example details (PDF) Simpson Strong-Tie
- 2025 Specification for Structural Joints Using High-Strength Bolts (PDF) Research Council on Structural Connections
Prepared with AI assistance. Linked references require current project-specific review. How these guides are prepared.
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