Question 1

What size header do I need for a window?

Accepted Answer

For windows up to 4 ft wide in a load-bearing wall with one story above, use a doubled 2x6 header. For up to 6 ft, use doubled 2x8. For up to 8 ft, use doubled 2x10. For 8 to 10 ft, use doubled 2x12. Always use jack studs (one for openings under 6 ft, two for wider spans) on each side. For non-load-bearing walls, the header can be smaller.

Question 2

What is a header in framing?

Accepted Answer

A header is a horizontal structural beam installed above a window or door opening to transfer the load from above (roof, floor, or wall) to the jack studs on either side. Headers prevent sagging at the opening and are required by code for any opening in a load-bearing wall. Common header materials include built-up dimensional lumber (typically two or three 2x members) and engineered LVL.

Question 3

Do interior walls need headers?

Accepted Answer

Headers are only required in load-bearing walls. For interior non-bearing walls (most interior partition walls in single-story homes and many in multi-story homes), you can use a flat 2x4 across the opening as a top of opening framer. Bearing walls run perpendicular to floor or ceiling joists and support a load from above. If unsure, treat any wall as bearing and consult an engineer.

Question 4

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

Accepted Answer

Walls running perpendicular to floor or ceiling joists are usually load-bearing because they support the joist ends. Exterior walls are almost always load-bearing. Walls aligned with joists (parallel) are usually non-bearing. Walls below a beam or supporting a wall above are bearing. The safest approach is to assume any wall is bearing and verify with a structural engineer or by checking framing plans.

Question 5

How many jack studs do I need on each side of a header?

Accepted Answer

Per IRC, openings up to 6 ft wide need one jack stud per side. Openings 6 to 12 ft wide need two jack studs per side. Openings over 12 ft typically need three jack studs or an engineered design. Jack studs (also called trimmers) sit beside the king studs and directly support the ends of the header. King studs run full wall height and are nailed to the header for lateral support.

Question 6

Should I use LVL or built-up lumber for a header?

Accepted Answer

Built-up dimensional lumber (e.g., doubled 2x10) is cheaper and works for most residential headers under 10 ft. LVL (laminated veneer lumber) is straighter, stronger, more dimensionally stable, and allows shallower headers for the same span. LVL is the better choice for headers over 10 ft, for headers in 2x6 walls (where width matches), or where you want a thinner header to maximize window height.

Question 7

What load should I use to size a header?

Accepted Answer

Use the load that comes from above the header. Roof-only loads are smallest (typical for single-story homes). One floor + roof loads are larger. Two floors + roof loads are largest. Snow load also matters: heavier snow regions (like the Northeast or mountain states) require larger headers than southern climates. The IRC tables include adjustments for snow load up to 70 psf.

Opening	Roof Only	Roof + 1 Floor	Roof + 2 Floors
4 ft	(2) 2x4	(2) 2x6	(2) 2x8
6 ft	(2) 2x6	(2) 2x8	(2) 2x10
8 ft	(2) 2x8	(2) 2x10	(2) 2x12
10 ft	(2) 2x10	(2) 2x12	(3) 2x12

Header Size Calculator

Opening Width

Load Above Header

Header Material

All Built-up Lumber Options for 1 story + roof

How to Size a Header

IRC Prescriptive Tables

Common Header Sizes by Load

Jack and King Studs

Header Filler and Insulation

Interior Non-Load-Bearing Openings

Frequently Asked Questions

Opening Width

Load Above Header

Header Material

All Built-up Lumber Options for 1 story + roof