What is the difference between a ridge board and a ridge beam?

A ridge board is a non-structural member that aligns the rafters at the peak. It relies on collar ties and ceiling joists to prevent the roof from spreading. A ridge beam is a structural member (usually LVL, glulam, or steel) that carries the full roof load, eliminating the need for collar ties and allowing open cathedral ceilings.

What size ridge board do I need?

The ridge board must be at least one nominal size deeper than the rafters so the rafters bear fully against it. For 2x6 rafters, use a 1x8 or 2x8 ridge. For 2x8 rafters, use a 1x10 or 2x10 ridge. For 2x10 rafters, use a 1x12 or 2x12 ridge board.

How many ridge boards do I need?

Divide the total roof ridge length by the board length you plan to use (12 or 16 feet). For a 40-foot ridge using 16-foot boards, you need 3 boards. Add one extra for waste. Joints between ridge boards must occur at a rafter location so both boards are supported.

Can I use a 1x board or do I need a 2x ridge board?

A 1x board (3/4-inch thick) is acceptable for a non-structural ridge board since it only serves as a nailing surface and alignment guide. A 2x board provides more rigidity during construction and is easier to work with. If the ridge must carry any structural load, a full-dimension 2x or engineered beam is required.

Do I need a structural ridge beam for a cathedral ceiling?

Yes. If you are building a cathedral or vaulted ceiling where collar ties and ceiling joists are not possible, you must use a structural ridge beam. The beam must be sized by an engineer based on the roof span, load, and local code requirements. Posts supporting the ridge beam must transfer loads down to the foundation.

How do I support a ridge board during construction?

Temporarily brace the ridge board with vertical supports (2x4 braces to the floor or temporary walls) while setting the first few pairs of rafters. Once several pairs of opposing rafters are nailed in place, the ridge board is held stable by the rafter connections. Remove the temporary bracing after the roof is fully framed and sheathed.

What size ridge board do I need?

The ridge board must be at least one nominal size deeper than the rafters to provide full bearing contact. For 2x6 rafters, use a 1x8 or 2x8 ridge. For 2x8 rafters, use a 1x10 or 2x10. For 2x10 rafters, use a 1x12 or 2x12. The ridge board thickness can be 1x or 2x since it is non-structural in a conventional rafter roof with collar ties.

Do I need a ridge board or ridge beam?

Use a ridge board (non-structural) when your roof has collar ties or ceiling joists that form a structural triangle with the rafters. Use a structural ridge beam when there are no horizontal ties, such as in cathedral or vaulted ceilings. A ridge beam must be engineered (LVL, glulam, or steel) and sized to carry the full roof load, with posts at each end bearing down to the foundation.

How long can a ridge board span?

A ridge board can span any length because it is non-structural — it is simply joined end-to-end with butt joints at rafter locations. Each joint must land on a rafter pair for support. A structural ridge beam, however, has span limits based on its size: a 3.5x11.25-inch LVL beam can typically span 16 to 20 feet, while longer spans require deeper beams or intermediate support posts.

What is the difference between a ridge board and ridge beam?

A ridge board is a non-structural member (usually 1x or 2x lumber) that aligns opposing rafters at the peak and relies on collar ties or ceiling joists to prevent the roof from spreading. A ridge beam is a structural member (LVL, glulam, or steel) that carries the full weight of the roof, eliminating the need for collar ties and enabling open cathedral ceilings. Ridge beams cost significantly more and require posts to the foundation.

Free Ridge Board Calculator — Length & Count (2026)

Ridge board calculator: How many boards for my roof peak? Free tool for 2x8, 2x10 & 2x12 ridge boards — gives length and count.

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How to Use This Calculator

1Enter total roof length.
2Enter the board length you will use.
3Click Calculate.

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About This Material

The ridge board runs along the peak of the roof and serves as the connecting member where opposing rafters meet. In a traditional rafter roof with collar ties, the ridge board is non-structural — it simply aligns the rafters and provides a nailing surface. It must be at least one nominal size deeper than the rafters to provide full bearing (for example, a 2x10 or 1x10 ridge board with 2x8 rafters). Common board lengths are 12 and 16 feet, joined end-to-end at rafter locations. A structural ridge beam is different — it is an engineered beam (LVL, glulam, or steel) that carries the full roof load without requiring collar ties or ceiling joists, allowing open cathedral ceilings. Structural ridge beams are significantly more expensive and require posts at each end bearing down to the foundation. Standard ridge boards cost $15 to $40 each depending on size and length, while structural ridge beams can cost $200 to $1,000+ depending on span.

Next Steps:

Rafter Calculator →Roof Sheathing Calculator →

Installation Tips

•Temporary support the ridge board while setting rafters.
•Keep the ridge board straight — use temporary bracing.
•The ridge board does NOT carry structural load in a traditional rafter roof (collar ties and walls carry the load).

Common Mistakes to Avoid

Using the same size as rafters — ridge must be one size larger to provide full bearing.
Not supporting the ridge during construction.

Free Ridge Board Calculator — Length & Count (2026)

How to Use This Calculator

About This Material

Installation Tips

Common Mistakes to Avoid

Frequently Asked Questions

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