A header is the horizontal member spanning a door, window, or wall opening. Above a load-bearing wall, the header transfers all loads from the wall, ceiling, and roof above the opening down to the king studs and jack studs on either side. Wrong header sizing causes immediate sag, drywall cracking, and over time a structural failure. The Ontario Building Code (Section 9.23) provides span tables for typical residential conditions.

This guide covers a typical interior load-bearing header for a doorway up to 8 feet wide. Larger spans (over ~10 feet) and unusual loading require engineered drawings.

Before you start

Three things to settle:

1. Confirm the wall is load-bearing first. Not every wall above a doorway is load-bearing. Walls perpendicular to floor/ceiling joists usually are; walls parallel often aren't. Check joist direction in the basement or attic. Misidentifying a load-bearing wall and undersizing the header is a common DIY mistake. Confirm with engineering or a designer if uncertain.

2. Header size from span tables or engineering. OBC Table 9.23.13.1 gives header sizes for typical loading. Roof loads only (one storey above): 2-2×8 covers ~6-8 ft openings depending on snow load. Two storeys above: heavier headers (2-2×10 or 2-2×12). Above 10 ft span or unusual loading: engineered (LVL, steel).

3. Temporary support before cutting. Removing wall studs above the opening releases the load above. Without temporary support (shoring), ceiling and floors sag immediately. Build temporary 2×4 wall ~4 ft away from the work area and load-transfer to it before any structural cuts.

What you'll need

Tools

Reciprocating saw or oscillating multi-tool
Circular saw or mitre saw
Drill with bits and driver
Hammer
Framing square and speed square
Tape measure
Level (4-foot)
Stud finder
Pry bar
Safety glasses, hearing protection, dust mask

Materials

Header lumber: typically 2×8, 2×10, or 2×12 doubled (sized per span tables or engineer)
1/2 inch OSB or plywood spacer (to bring built-up header to 3.5 inch wall thickness)
16d framing nails or 3-inch construction screws
Construction adhesive (PL Premium)
Jack studs and king studs (2×4 lumber)
Cripple studs (short studs above header)
Temporary shoring lumber (2×4s)

Build a temporary wall before cutting structural members

Approximately 4 ft from the planned opening, build a temporary 2×4 wall floor-to-ceiling. Cut the top plate, studs (16 inch on-centre), and bottom plate to fit. Stand it up snug with a few wedges or shims at the top.

This wall transfers load from the ceiling through to the floor, freeing the work area to be cut. Don't skip this — a 4 ft wide opening with no shoring will visibly sag the ceiling within hours.

Step-by-step instructions

Confirm load path and header size

Identify what's above the wall: roof only, attic + roof, second floor + roof, or larger.

Look up header size in OBC span tables for the loading and span. Or hire engineer for confirmation.

Common: 2-2×8 with 1/2 inch plywood spacer for openings up to 6-8 ft under one storey + roof.

Build temporary shoring 4 ft from opening

Build a temporary stud wall floor-to-ceiling, parallel to and 4 ft from the planned opening.

Tighten with shims or wedges at the top — should bear firmly against the ceiling.

This carries the load while you remove existing studs.

Mark the opening location

Mark king stud locations on the bottom plate at the outside of the opening (king studs run full floor-to-ceiling and frame the entire opening).

Mark jack stud locations 1.5 inches inside the king studs (jack studs support the header from below).

Mark header height: bottom of header at door/window's intended top trim height + room for header thickness.

Remove existing studs in the opening area

Use a reciprocating saw to cut existing studs flush with the bottom plate (or floor if no plate).

Pry studs out. Save useable lumber.

Caution: cut wires before cutting studs. Use a stud finder to locate any electrical.

Install king studs and jack studs

Cut king studs to floor-to-ceiling length. Position at outside of opening; nail/screw to top plate and bottom plate.

Cut jack studs: total opening height (bottom of header) − bottom plate thickness (1.5 inches). Position inside king studs; nail to king studs.

Build the header

Cut two pieces of header lumber to length: opening width + jack-stud width × 2 (typically 3 inches additional total).

Sandwich header lumber with 1/2 inch OSB or plywood spacer between to achieve 3.5 inch wall thickness for 2×4 wall.

Glue with construction adhesive between layers; nail/screw together every 12 inches in two rows.

Install the header

Lift header into position above jack studs. Should bear fully on the jack studs.

Nail/screw header to king studs (toe-nail through the side) — multiple connections per side.

Verify level.

Install cripple studs above header

Cripple studs: short studs between top of header and top plate, at 16 inches on-centre.

Cut to length: top plate to top of header.

Nail/screw to header from below and top plate from above.

Remove temporary shoring and verify

After all framing is in and the load path is established (header → jacks → king studs → bottom plate → floor), remove temporary shoring.

Verify ceiling is still flat — no sag across the opening.

If sag is visible: header is undersized; shore back up and recalculate.

Common mistakes that cost you

Skipping temporary shoring. Ceiling sags within hours. Always shore before cutting.
Header too small. Visible sag, drywall cracks. Use OBC span tables or engineer for sizing.
No spacer in built-up header. Doubled 2×8 = 3 inches; 2×4 wall is 3.5 inches. 1/2 inch spacer required to fit flush.
Jack studs missing. Header bears on king studs only — they transfer load partially through nails. Jack studs provide direct load path.
Nailing alone. For built-up headers, glue + nails or glue + screws. Glue prevents the laminations from racking.

Frequently asked questions

How do I know if a wall is load-bearing?

Check joist direction. If floor/ceiling joists run perpendicular to the wall, it's likely load-bearing. Parallel joists, often not.

Walls running through the centre of the house (running with the long axis): often load-bearing.

Walls in the basement directly under upstairs walls: load-bearing path.

When in doubt, hire an engineer for a stamp confirming.

When do I need an engineered header (LVL, steel)?

Spans over 10 ft, unusual loading (point load above), or removing more than one stud bay continuously.

Engineered LVL beams handle longer spans in less depth than dimensional lumber.

LVL costs more per linear foot than dimensional lumber, but the added span capacity is often worth it.

Do I need a permit?

Yes for any structural change in Ontario — including modifying load-bearing walls. Pull a building permit through Ottawa's MyServiceOttawa portal.

Permit fees start at $117 minimum. Inspector verifies header sizing and connections.

When to call us instead

Removing or modifying load-bearing walls is structural work. Our team handles wall removal, header installation, and engineering as part of renovations.

Book a free 60-minute site visit →

Related Ottawa services

If you're opening up walls in a renovation, our team coordinates engineering, permits, and structural work. Book a free 60-minute consultation.