FAQs

The calculator is set up to receive specific inputs for building plan dimension and Band identification, based on your design. These inputs are entered in a specific organised way to allow the calculator to perform the calculations. The calculator will not function properly if the inputs are not entered in the specific way. Please review this video, and image, for clarity on how each input in the calculator relates to your design.

Note: The tool is currently set up with Bands oriented vertically, labelled along the horizontal axis, as 1, 2, 3 etc. Bands oriented horizontally, labelled along the vertical axis, as A, B, C etc. This decision was made based on feedback from designers on standard drawing conventions. Please recognize that this labelling setup is different to the BC Housing Illustrated Guide. A future version will include functionality for a user to select their preference before identifying their Bands in the (I-3) Design & Feedback sheet.

This means that your location is not listed in the Appendix C of the BCBC. To use the calculator, please review this video on entering a Custom Location. By navigating through to the (A-2) C-2 & C-3 Generator sheet, users can recall site specific seismic and climate data for any any location in the Province. For those interested, this functionality will soon be available for any location nationally.

Occasionally, when navigating from sheet to sheet, Google Sheets incorrectly locates the Buttons in the user interface - and they can be misplaced and look like this instead of this. Try navigating to another sheet and back again, to give the sheet an opportunity to reset correctly.

In the context of the Part 9 Bracing Calculator, a Braced Storey is a building storey that requires calculation of bracing lengths through BCBC 9.23.13.7.(3) and (4). In a Slab-on-Grade construction building, all storeys will be Braced Storeys.

A Relaxed Braced Storey relates to a Basement/Crawlspace that is permitted to use a code Relaxation of BCBC9.23.13.5.(2), 9.23.13.8, or 9.23.13.9. to reduce the amount of bracing length required in that storey. The amount of bracing length in a Relaxed Braced Storey is dependent on the amount of bracing length in the Braced Storey above (the tool automatically make these calculations). Note that, in some situations these Relaxation clauses are quite restrictive, and if a Basement/Crawlspace does not meet the permissions, the Basement/Crawlspace is required to be designed as a Braced Storey. 

The determination of Braced Storeys and Relaxed Braced Storey is made by the calculator automatically in the responses to questions on the (I-1) General sheet.

CFW-FH stands for Concrete Foundation Wall – Full Height. This reference framing type is used within the Part 9 Bracing Calculator to account for full-height concrete foundation walls that extend up to the underside of the first wood-frame floor, and are relied upon to resist lateral loads.

Although the BC Building Code (Part 9) does not currently provide prescriptive bracing length design values for this type of concrete construction, some designs may require it to facilitate calculation.

The Part 9 Bracing Calculator uses CFW-FH as a proxy category, assigning it the same bracing capacity values as the strongest wood-sheathed option: WSP-E.

This is a placeholder assumption based on alignment with the best-performing prescriptive wood system, and it ensures the calculator remains functional until such time as code authorities prescribe the shear capacity of concrete foundation walls that extend to the underside of floor systems.

Important:

• This designation is not recognized by code but is a functional tool within the calculator.

• Users should consult with their AHJ for approval of this use.

BCBC2024 [B] 9.23.13.7.(6) provides specific prescriptive permission to reduce the amount of required bracing length by 50%, if a gypsum sheathed Reference Framing Type panel is applied to both sides of a wood-framed wall. Within the Part 9 Bracing Calculator, the user selections for Reference Framing Type, with suffix of "-2", provide opportunity for users to make this permitted adjustment.

The Short Answer:

The Part 9 Bracing Calculator currently uses the "Calculation Approach" (aka "Calculation Method") outlined in BCBC2024 [B] 9.23.13.7 — to determine required bracing length. It does not use the Simplified Approach described in BCBC2024 [B] 9.23.13.11.

The Long Answer:

Subsection 9.23.13 outlines two permitted ways to calculate an amount bracing length; the Simplified Approach, and the "Calculation Approach". Furthermore, the "Calculation Approach" can be used via two methods: the "Tables Method" and the "Alternative Method". This code framework is detailed below:

1. Simplified Approach (9.23.13.11): A limited method that can only be used in certain locations and for buildings that meet specific design and layout restrictions. This article uses table references to make a determination on required length. This approach is not used by the Part 9 Bracing Calculator.

2. "Calculation Approach" (9.23.13.7): A more flexible method permitted across all BC locations, including those with higher seismic or wind loads. This method contains two subset methods for determining required length.

   • The "Table Method": This method uses table references 9.23.13.7.A-D to determine Unadjusted Length and then requires these values to be multiplied by Adjustment Factors. Climate and seismic design loads are bracketed (to within a range of values) within the tables. This method is referenced through the Part 9 Bracing Calculator as Calculation Method (Tables) or Tables.

   • The "Alternative Method": Outlined in the Notes A-9.23.13.7, this method inputs direct climate and seismic design loads into the equation to calculate required bracing length, and as such provides greater fidelity in its results. This method is referenced through the Part 9 Bracing Calculator as Calculation Method (Alternative) or Alternative.

Either the Simplified Approach or the "Calculation Approach" must be used to determine required bracing length under BCBC2024 [B] 9.23.13 (unless a specific exemption applies, or a structure is professionally engineered).

The Part 9 Bracing Calculator exclusively uses the "Calculation Approach" and, where possible, provides results for both the "Table Method" and the "Alternative Method". 

⚠️ Confusion on the term “Table Method”:

Some external user guides refer to the Simplified Approach as the “Table Method” — this makes sense, as this method does use tables, however, it has also led to some confusion with users of the Part 9 Bracing Calculator.

This FAQ is to clarify that the Part 9 Bracing Calculator's "Table Method", as referenced in the tool, is not based on the Simplified Approach. It is a subset of the "Calculation Approach" under 9.23.13.7 and is a compliant method across all locations in BC (except Whistler, in which case the subset "Alternative Method" can be used).