How to install a hollow metal door frame the right way

Hollow metal frames are the workhorse of commercial construction, but a poor install can ruin a perfectly good door. The two biggest enemies are racked frames and out-of-plumb jambs — both will fight you every time the door swings.

Before you uncrate anything

• Confirm the rough opening: 2" wider and 1" taller than the nominal frame size is a safe rule for knock-down (KD) frames.
• Check the floor for level across the full width of the opening. Shim if you're more than 1/8" off across 3 feet.
• Identify your jamb depth and make sure the wall thickness matches. A 4-3/4" jamb on a 6-3/4" wall is going to look weird and feel worse.
• Verify handing against the door schedule. Don't trust the box label — frames get mis-labeled at the factory more often than you'd think.

Knock-down frames: 6 steps

1. 1Assemble the frame on the floor next to the opening. Slip the head into the jamb tabs and tap together with a rubber mallet. Square it by checking diagonal measurements — they should be within 1/16".
2. 2Set the frame into the rough opening with the door-stop side facing the swing direction. Most KD frames are designed so the floor anchors slide into the bottom of each jamb.
3. 3Plumb the hinge jamb first using a 6-foot level. Shim behind the hinge locations — at the top, middle, and bottom — until the jamb is dead plumb.
4. 4Drive the floor anchors into the slab. Use power-actuated fasteners or Tapcons rated for the slab thickness.
5. 5Plumb the strike jamb. Check that the gap between the door and the jamb (the reveal) is consistent — typically 1/8" — across the full height. Shim until it is.
6. 6Fasten the frame to the studs through the jamb anchors. Don't over-tighten — that's what racks the frame and binds the door.

Face-welded frames

Welded frames arrive as a single rigid unit. The good news: no on-site assembly. The bad news: if it's out of square when it arrives, you can't easily fix it. Set them in place with two people, brace them to keep them from racking, and anchor the same way as KD frames. Inspect every welded frame for square before you commit to the opening.

Common mistakes

• Skipping the diagonal check. If the frame isn't square going in, no amount of shimming downstream will fix it.
• Anchoring before plumbing. Drive your anchors only after you've confirmed plumb at the hinge jamb.
• Forgetting the head anchor. The header needs to be tied into the framing or it'll deflect under door-closer load.
• Using the door as a template. Always measure independently. Frames and doors are manufactured separately and don't always agree.

A frame that's plumb, square, and properly anchored will make every other step of the opening — hardware install, weather seal, paint — go faster and last longer.