Wall Stud Calculator — Raked Wall Pitch & Stud Length
Calculate individual stud lengths for raked walls using the roof pitch angle. Enter the starting wall height, pitch angle, stud spacing, and number of studs to get a complete cut list. This wall stud calculator is essential for framing cathedral ceilings, skillion roofs, and gable ends in Australian homes.
How to Calculate Stud Lengths from Pitch Angle
When you know the roof pitch angle (in degrees), the formula for each stud is:
Stud Length(n) = Starting Height + (n × Stud Spacing × tan(Pitch Angle))
Where n is the stud number (starting from 0). The tan(pitch) value converts the horizontal spacing into the vertical rise for each stud.
Quick Reference: Rise Per Stud at Common Pitches
| Pitch Angle | Rise per 450mm | Rise per 600mm | tan(pitch) |
|---|---|---|---|
| 5 deg | 39mm | 52mm | 0.0875 |
| 10 deg | 79mm | 106mm | 0.1763 |
| 15 deg | 121mm | 161mm | 0.2679 |
| 20 deg | 164mm | 218mm | 0.3640 |
| 22.5 deg | 186mm | 249mm | 0.4142 |
| 25 deg | 210mm | 280mm | 0.4663 |
| 30 deg | 260mm | 346mm | 0.5774 |
| 35 deg | 315mm | 420mm | 0.7002 |
Stud Spacing Requirements (AS 1684)
The spacing between studs in a raked wall depends on the load and wind classification:
- 450mm centres: Required for load-bearing external walls in wind classifications N3 and above. Also used for walls supporting tile roofs or heavy point loads
- 600mm centres: Standard spacing for load-bearing walls in N1 and N2 wind areas. Most common in residential construction across southern and eastern Australia
- Non-load-bearing internal walls: Can use 600mm centres regardless of wind classification. Some builders use 450mm for better plasterboard support
Worked Example: Raked Wall Stud Cut List
Scenario: Cathedral ceiling with 2,400mm starting height, 22.5-degree pitch, 600mm spacing, 8 studs:
| Stud # | Position | Rise Added | Cut Length |
|---|---|---|---|
| 1 | 0mm | 0mm | 2,400mm |
| 2 | 600mm | 249mm | 2,649mm |
| 3 | 1,200mm | 497mm | 2,897mm |
| 4 | 1,800mm | 746mm | 3,146mm |
| 5 | 2,400mm | 994mm | 3,394mm |
| 6 | 3,000mm | 1,243mm | 3,643mm |
| 7 | 3,600mm | 1,491mm | 3,891mm |
| 8 | 4,200mm | 1,740mm | 4,140mm |
Note: These are stud lengths between plates. Subtract top and bottom plate thickness (typically 35mm each) from your floor-to-ceiling measurement to get the starting height for the calculator.
When to Use Pitch vs Two Heights Method
- Use Pitch method (this calculator) when you know the roof pitch angle from the plans or from the roofing material specification. Best for new builds where the pitch is specified
- Use Two Heights method when you know the wall height at each end but not the pitch. Common for renovations where you measure the existing structure
Important Considerations for Raked Wall Studs
- Bevel cut the top: The top of each stud needs a bevel matching the pitch angle so the top plate sits flat against the rafter or roof plane
- Nogging: Install horizontal nogging at mid-height for any studs exceeding 2,700mm. For a raked wall, this means nogging is required in some bays but not others
- Stud size: If any stud in the raked wall exceeds 3,000mm, consider using 90x45mm or 140x35mm studs for the entire wall for consistency. See our main raked wall calculator for timber sizing guidance
- Order extra: Allow 10% extra timber for waste, bevel cuts, and off-cuts that are too short to use
“Print out your stud cut list and label each stud with its number and length before you start cutting. This simple step prevents costly mistakes, especially on long raked walls with 15-20 studs of different lengths.”
— Carpenter and framing contractor, Brisbane
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