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Deflection Track and Head-of-Wall Details: Why Metal Stud Walls Need Room to Move

What deflection track is, why metal stud partitions need a slip joint at the top, and how head-of-wall details prevent cracked drywall in commercial buildings.

By SCCI Drywall. Published 2026-10-22.

Key Takeaways

  • Floor and roof decks move under load; partitions tied rigidly to them can crack or buckle.
  • Deflection track lets the deck move up and down without loading the wall.
  • The drywall and studs must not be screwed into the moving leg of the track.
  • Fire-rated walls need a listed head-of-wall joint system at the top.

Cracks at the top of a commercial wall, bowed studs, or drywall that pops loose along the ceiling line are often caused by one missing detail: room for the building to move. That's what deflection track is for.

Why Buildings Move

Floors and roofs bend slightly under load. When people, furniture, equipment, wind or rooftop units add weight, the deck above a wall can move down. In some conditions it moves up. The amount is small, but if a partition is fastened tightly to that deck, the wall gets squeezed or pulled. The result can be cracked drywall, buckled studs and doors that bind.

What Deflection Track Does

Deflection track is a top track designed to let the deck move independently of the wall. Common approaches include:

  • Deep-leg track: a top track with extra-long legs. Studs sit inside it with a gap at the top and aren't screwed to the track, so the deck can move down into that space.
  • Slotted track: track with vertical slots in the legs. Studs are fastened through the slots, so they're held in place but can slide up and down.
  • Double track: a nested track system that creates a slip joint between the inner and outer track.
  • Clips: specialty clips that connect studs to structure while allowing vertical movement.

The Drywall Detail Matters, Too

A perfect deflection track is useless if the drywall locks it up. At the top of the wall:

  • Don't screw drywall into the moving top track
  • Leave a gap between the board and the deck, as the design requires
  • Finish the joint with a sealant, trim or listed joint system rather than hard-taping it to the ceiling

Fire-Rated Head-of-Wall Joints

On fire-rated walls, the gap at the top can't just be left open. It has to be filled with a tested head-of-wall joint system that both allows movement and maintains the fire rating. The drawings or submittals will reference a specific listed system, and the installation must match it. Learn more in our guide to fire-rated drywall assemblies.

Where You'll See It

  • Interior partitions under steel deck and concrete floors in multistory buildings
  • Walls under long-span roof structures in retail and warehouse spaces
  • Corridor and demising walls that run to the deck. See tenant improvement drywall
  • Shaft walls and stair enclosures. See shaft wall systems

Signs a Wall Needed It

  • Horizontal cracking along the top of the wall
  • Drywall joints cracking near the ceiling on upper floors
  • Doors that start binding after the space is occupied

Built Right by SCCI Drywall

SCCI Drywall frames metal stud partitions with the head-of-wall details your project calls for, and finishes them so the movement joint stays clean. Call (210) 875-0280. Also see metal stud layout, track and blocking.

Frequently Asked Questions

What is deflection track?

A top track for metal stud walls that lets the floor or roof deck above move up and down without crushing or pulling the wall.

Why is my commercial wall cracking at the ceiling?

A common cause is a wall fastened rigidly to a deck that moves. A proper deflection detail at the top helps prevent it.

Can a fire-rated wall have a gap at the top?

Only if it's filled with a tested head-of-wall joint system that allows movement and keeps the rating.

Contact SCCI Drywall

SCCI Drywall serves San Antonio and all of South Texas with drywall installation, drywall repair, remodeling, metal stud framing, light gauge framing and acoustical grid ceiling systems for residential and commercial projects.

Phone: (210) 875-0280

Email: sccidrywall@gmail.com

Hours: Monday through Friday, 7:00 AM to 6:00 PM

Request a free drywall quote