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# Design Wind Bracing to AS 1684.2:2021
> Wind bracing design to AS 1684.2:2021 and AS 4055:2021. Find wind pressures and racking forces, then size bracing length for Class 1 residential buildings.
AustraliaAS 1684.2:2021AS 4055:2021
Wind bracing analysis and design to AS 1684.2:2021 and AS 4055:2021. Calculate wind pressures and racking forces from building configuration, then size total bracing length across long- and short-side walls for Class 1 residential buildings.
The Calcs.com Wind Bracing Calculator to AS1684.2 is a quick and easy tool for performing wind bracing analysis and design to Australian codes. With customization options, intuitive interface and a broad selection of commonly used bracing types, users can design their structural bracing system while considering various site situations. Ensure the safety and stability of your structure with fast and accurate designs provided within minutes by Calcs.com Wind Bracing Calculator.
## Method & scope
| Property | Detail |
| ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Design standards | AS 1684.2:2021, AS 4055:2021 |
| Regions | Australia & New Zealand |
| Who it's for | Australian structural engineers designing wind bracing for hip and gable end buildings to AS 4055:2021. |
| What it helps with | Calculate wind pressures and racking forces from building configuration, then size total bracing length across long- and short-side walls. |
| What it checks | Step 1 , Design wind pressure from AS 4055:2021, Step 2 , Racking demand from area of elevation, Step 3 , Bracing capacity from AS 1684.2:2021, Step 4 , Pass/fail check |
#### Calculation method
The calculator works through four sequential steps: determining design wind pressure for each wind direction, calculating the racking demand on each wall face, tallying the bracing capacity provided, and checking that capacity meets demand. Each step is performed independently for the long-side (wind on side) and short-side (wind on end) of the building.
##### Step 1 , Design wind pressure from AS 4055:2021
Wind pressure depends on how the wind approaches each face of the building.
For **vertical surfaces** (flat gable ends, skillion ends, and walls presenting a flat face to the wind), the calculator looks up the design wind pressure directly from Table 5.2(A) of AS 4055:2021 using the wind classification. The values for non-cyclonic sites are:
* N1: 0.66 kPa
* N2: 0.92 kPa
* N3: 1.44 kPa
* N4: 2.14 kPa
For **sloped roofs** (hip roofs and side wind on gable or skillion roofs), the calculator interpolates across Tables 5.2(B)-(I) of AS 4055:2021 using both roof pitch (0-35°) and building width as inputs. Wind class and story level (single story / upper story versus lower story of a two-story building) determine which sub-table governs. Because the sloped-roof pressure depends on building width, the long-side and short-side of the same building may produce different pressures even at the same wind class.
Roof pitch must be between 0° and 35° (70:100 slope), and building width must be less than 16 m , both are enforced by the calculator in accordance with the scope of AS 4055:2021.
##### Step 2 , Racking demand from area of elevation
The racking demand (kN) acting on each wall face is the product of the design wind pressure and the area of elevation facing that wind direction, per AS 1684.2:2021 Cl 8.3.4:
**F* = p\_u × A*\*
The area of elevation can be entered in two ways. When **auto-calculation** is selected, the calculator derives the long-side area from wall height and building length, adding the gable or hip triangle contribution using roof pitch. The short-side area is derived similarly using building width. When **custom areas** are selected, the user supplies the projected areas directly , required for L-, H-, or U-shaped plans, buildings with enclosed verandahs, or any geometry where the standard formula would not capture the true exposed surface.
##### Step 3 , Bracing capacity from AS 1684.2:2021
Bracing capacity is assembled from up to three sources for each wall direction.
**Structural wall bracing** is chosen from the 18 bracing types listed in Table 8.18 of AS 1684.2:2021. Unit capacities range from 0.8 kN/m for type (a) two diagonally opposed timber/metal angle braces up to 7.6 kN/m for type (i) 7 mm F11 plywood and type (m) Hardboard Type C. The user nominates the bracing type and total installed length; the calculator multiplies these to obtain the bracing capacity for each row and sums across all rows.
Two adjustments modify the raw table values:
* **Wall height multiplier** (Table 8.19, Cl 8.3.6.4): For wall heights greater than 2.7 m, all bracing capacity is scaled down by the ratio 2700 mm / H\_w. A 3.6 m wall, for example, attracts a multiplier of 0.75.
* **Joint group uplift** (Cl 8.3.6.3): If the timber framing is JD4 rather than the default JD5, the capacity of sheet bracing types (g) to (k) is increased by 12.5% and types (l) to (n) by 16%.
**Nominal wall bracing** (Cl 8.3.6.2) represents sheet lining fixed to the framing without purpose-fitted bracing hardware. One-side-sheeted walls contribute 0.45 kN/m and two-side-sheeted walls contribute 0.75 kN/m. The total nominal bracing capacity credited to the design is capped at a user-controlled percentage of the racking demand , by default 50% per the standard, but this can be set lower.
**Custom bracing** allows users to enter proprietary or non-standard bracing products not listed in Table 8.18, supplying their own unit capacity (kN/m) and installed length. The wall height multiplier can be toggled on or off for each custom row, accommodating products where the manufacturer's capacity already accounts for wall height variation.
Total racking capacity for each direction is the sum of structural bracing capacity, nominal bracing capacity (capped), and any custom bracing capacity.
##### Step 4 , Pass/fail check
The calculator compares total racking capacity against the racking demand for both the long-side and short-side walls independently. The design passes when:
**F\_total ≥ F**\*
If capacity is insufficient, a clear failure message identifies which wall direction needs additional bracing. Because eccentricities in wind loading and plan irregularities are excluded from scope, this is a global check , total capacity across the wall face versus total demand , consistent with the simplified approach in AS 1684.2:2021.
## How to use it
Open it from **Run calc** in the About this calculator panel above.
Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See [Checks, References, Conditions and Assumptions](/docs/running-calculations/checking-results/checks-references-conditions-assumptions).
Check the utilization of each governing check in the summary, then export a PDF report. See [Views and Export](/docs/running-calculations/exporting-reports/views-and-export).
## Common questions
The calculator uses AS 4055:2021 to determine design wind pressures and AS 1684.2:2021 to size the bracing. Wind classification (N1 to N4) is entered for both the long-side (wind on side) and short-side (wind on end) of the building, and wind pressure values are drawn directly from Table 5.2 of AS 4055:2021. Bracing unit capacities and the treatment of nominal bracing come from Section 8.3 and Table 8.18 of AS 1684.2:2021. Cyclonic wind classes (C1-C4) are outside the scope of both standards and are not covered.
The main inputs fall into three groups. First, wind classification: wind class (N1-N4), roof type (vertical surfaces or sloped roofs), building story level, and roof pitch (0-35°) for each wind direction. Second, building geometry: building length, width (≤ 16 m), wall height (≤ 6 m), and either the calculated or a custom area of elevation for each face. Third, bracing layout: timber joint group (JD4 or JD5), nominated lengths of structural wall bracing chosen from the 18 types in Table 8.18 of AS 1684.2:2021, lengths of nominal (sheet) bracing, and optional custom bracing with user-supplied unit capacities , all entered separately for the long-side and short-side walls.
For each wind direction the calculator reports the design wind pressure (kPa), the racking demand (kN) , derived from wind pressure multiplied by the area of elevation , and the total racking capacity (kN) from structural, nominal, and any custom bracing combined. A pass/fail check confirms whether total capacity meets or exceeds the racking demand for both the long-side (wind on side) and short-side (wind on end) walls. The wall height multiplier (Table 8.19) is applied automatically when walls exceed 2.7 m, and the JD4 capacity uplift is applied to sheet bracing types where relevant.
Yes, with a per-story workflow. AS 1684.2:2021 requires each floor level to be assessed separately, so you run the calculator once per story: select 'Single Story or Upper Floor of Two-story Building' or 'Lower Story of Two-story Building' from the bracing location dropdown, enter the corresponding wall height and area of elevation for that level, and size the bracing accordingly. The calculator does not automatically split loads across stories , each level is an independent calculation, which is the correct approach under the standard.
Use the custom area option any time the building footprint is not a simple rectangle or when the default formula would underestimate the exposed surface. The calculator derives the long-side area from wall height and building length, adding the gable or hip triangle contribution using roof pitch and building width. If the building has an L-, H-, or U-shaped plan, a verandah that will be enclosed, or a skillion end treated as a vertical surface on one side but a sloped roof on the other, enter the actual projected area directly. AS 4055:2021 Cl 5.2 requires the worst-case wind direction to govern, so complex shapes should always be verified with manual area take-offs before entry.
## Next steps
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