What is a collar tie?

A collar tie connects opposing roof rafters high in the attic to resist their separation near the ridge under uplift. It sits in the upper third of the attic space. Lower rafter ties resist outward thrust instead, so identify which member you have before requesting changes for more headroom.

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By InstaBids editorial team with AI research agents. Updated 2 November 2026

What this means for your home project

Use an existing attic photograph or roof section to mark whether the tie sits in the upper third of the attic; label that location in your project notes. Source: Greene County, Missouri, read 2026-11-02.
Request a written collar-tie connection schedule identifying nail type and count at each rafter, so the reply specifies the fastening rather than just “add ties.” Source: North Carolina Building Code Council / Office of Administrative Hearings, read 2026-11-02.
For a headroom proposal, ask whether ridge straps would replace the collar ties; request a reply that names the replacement connection. Source: North Carolina Building Code Council / Office of Administrative Hearings, read 2026-11-02.
If the project removes ceiling joists or rafter ties, request a roof section showing the proposed wall or designed girder supporting the ridge. Source: Greene County, Missouri, read 2026-11-02.

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What is the difference between a collar tie and a rafter tie?

The difference is the load each tie resists: collar ties connect the upper rafter ends against uplift, while low rafter ties or ceiling joists resist outward thrust from roof weight. The American Wood Council places that thrust resistance in the lower third of the attic. Wood Frame Construction Manual is the full name of WFCM in its explanation. “Ceiling joists or rafter ties resist outward thrust of the rafters in the lower third of the attic space.” Source: American Wood Council, read 2026-11-02. “Collar ties or ridge straps to resist wind uplift shall be connected in the upper third of the attic space.” Source: Greene County, Missouri, read 2026-11-02.

How far apart should collar ties be?

Greene County, Missouri’s residential guide gives a maximum spacing of 4 feet on center and a minimum nominal lumber size of 1 by 4 inches. On center means the distance between tie centers; nominal is the lumber size designation. This older local guide references the 2012 International Residential Code elsewhere; use it as an example to discuss with your designer, rather than a determination of your home’s requirements. “Collar ties shall be a minimum of 1 inch by 4 inches (nominal), spaced not more than 4 feet) on center.” Source: Greene County, Missouri, read 2026-11-02.

How do you nail collar ties?

Specify the nail type and count at each rafter connection. In the North Carolina 2024 residential-code rule submission, Table R602.3(1), item 5, lists face nailing with four 10d box nails, three 10d common nails, or four 3-inch-by-0.131-inch nails. Those alternatives are a reason to request a fastening schedule in the written scope. This is the submitted code text, not a determination of the code currently enforced at your home. “Where collar ties are used to connect opposing rafters, they shall be located in the upper third of the attic space and fastened in accordance with Table R602.3(1).” Source: North Carolina Building Code Council / Office of Administrative Hearings, read 2026-11-02.

Collar ties: can you remove some of them to create headroom?

A replacement ridge connection is one option to discuss before removing a collar tie for headroom. Section R802.4.6 in North Carolina’s 2024 residential-code rule submission permits ridge straps in place of collar ties. It also specifies the strap and its fastening; removing the wood alone does not describe that replacement work. Ask for a written proposal identifying the replacement connection. “Ridge straps shall be permitted to replace collar ties.” Source: North Carolina Building Code Council / Office of Administrative Hearings, read 2026-11-02.

Is it possible to replace these ceiling rafters with collar ties? Or do I need more support?

Collar ties address uplift near the ridge; they do not take over the lower ties’ job of resisting outward thrust. If “ceiling rafters” means ceiling joists, Greene County’s guide describes a different structural arrangement when joists or rafter ties are absent: a ridge supported by a wall or a designed girder, meaning a supporting beam. Keep that distinction in the scope of a ceiling-opening project. “Where ceiling joists or rafter ties are not provided, the ridge formed by these rafters shall be supported by a wall or girder designed in accordance with accepted engineering practice.” Source: Greene County, Missouri, read 2026-11-02.

Sources

What is the difference between a collar tie and a rafter tie? — American Wood Council; published 2021-09-27; read 2026-11-02.
Residential construction guide: roof framing (2012 IRC context) — Greene County, Missouri; read 2026-11-02.
2024 Residential Code rule submission: Section R802.4.6 and Table R602.3(1); council adoption September 12, 2023 — North Carolina Building Code Council / Office of Administrative Hearings; published 2023-09-12; read 2026-11-02.