净跨长度和椽条长度有什么区别？

净跨长度是从墙板外沿到脊檩中心的理论尺寸。椽条长度是实际下料尺寸：减去半个脊檩厚，再加上出檐。

脊檩厚度怎么处理？

计算前先从水平距离中减去脊檩厚度的一半。2x 脊檩即每根扣 1.9 厘米。忽略它会把两侧墙体外推近 4 厘米。

屋面出檐做多少合适？

通常 30–60 厘米。出檐大能遮阳并让雨水远离墙面，但在强风地区会增加掀起风险。

需要多少根椽条？

用建筑长度除以中心距再加一，然后按双坡加倍。12 米长的建筑按 40 厘米中心距，每侧 31 根，共 62 根。

下料要比计算长度多留吗？

要。按上一档标准长度采购：竖切口、鸟嘴口和檐口切割都会消耗长度，切短的椽条就是废料。

椽条计算器

根据建筑宽度与坡度计算普通椽条长度，包含沿坡出檐、脊檩厚度扣减、椽条数量以及应采购的木料长度。

公式与数据最后核对于 2026年8月6日 — Cosyslabs

输入

建筑宽度（外墙到外墙）(ft)

建筑长度(ft)

坡度（每 12 的升高）(/12)

出檐（水平投影）(in)

脊檩厚度(in)

椽条中心距(in)

每英尺单价（选填）($)

Result

Rafter length

14.5 ft

Line length (to ridge)

13.3 ft

Rafters (both sides)

Total rise: 5.97 ft
Total run: 11.9 ft
Overhang along slope: 1.12 ft
Buy length: 16 ft stock

Diagram

Estimates only. Verify with a licensed contractor or supplier before purchasing. Rough Estimator! is not responsible for shortages, overages, or material variances. See our methodology for formulas and sources.

公式

水平距离 = 宽度 ÷ 2 − 脊檩 ÷ 2   ·   长度 = √(水平距离² + 升高²)

参考资料

Measure what the tool asks for
This calculator works from 建筑宽度（外墙到外墙） in ft, 建筑长度 in ft and 坡度（每 12 的升高） in /12. Measure the finished area you are covering, not the material — an estimate is only as good as the dimensions you feed it.
What it does with those numbers
水平距离 = 宽度 ÷ 2 − 脊檩 ÷ 2 · 长度 = √(水平距离² + 升高²) Every figure on the page comes out of that one expression, so you can check it by hand.
Where the numbers come from
The constants are taken from American Wood Council — Span Tables for Joists and Rafters and IRC R802 — Roof-ceiling construction, linked in full below. If a figure here disagrees with your supplier's spec sheet, use the spec sheet — it describes the product you are buying.
What this will not tell you
This is a material takeoff, not a bid. It does not price labour, permits, delivery, equipment hire or site preparation, and it assumes a straightforward layout. Complex cuts, difficult access and awkward shapes all cost more than the geometry suggests.

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椽条木料
脊檩
抗风连接件
系梁
椽间挡块

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常见问题

椽条沿直角三角形的斜边：水平距离为建筑半宽减去半个脊檩厚，升高为水平距离乘坡度除以 12，长度取两者平方和的开方。

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Cite this page

Cosyslabs. (2026). 椽条计算器. Rough Estimator!. https://roughestimator.com/zh/rafter-calculator

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