Letters of Assurance for Part 9 Buildings

What are Letters of Assurance?

Letters of Assurance are legal accountability documents that are required under the Building Code, intended to clearly identify the responsibilities of key participants in a construction project such as the owner, architect, or professional engineer. These documents were established to assure professional accountability and coordination of professionals involved on a project to avoid failures such as the Station Square collapse. The requirements for Letters of Assurance are outlined in the 2018 BC Building Code Subsection 2.2.7. in Part 2 of Division C.

Schedule A: Confirmation of Commitment by Owner and Coordinating Registered Professional
Schedule B: Assurance of Professional Design and Commitment for Field Review & Summary of Design and Field Review Requirements
Schedule C-A: Assurance of Coordination of Professional Field Review
Schedule C-B: Assurance of Professional Field Review and Compliance

Letters of Assurance are not to be confused with “Schedule D” or “Schedule E” (Commonly referred to as the Owner’s Undertaking Letters”). Letters of Assurance are different than other accountability documents that may be used or required by the Authority Having Jurisdiction (AHJ) on matters outside the scope of BCBC 2.2.7. Additionally, Letters of Assurance are not appropriate accountability documents for the author of an Alternative Solution. An AHJ may require a letter of commitment from a registered professional when Letters of Assurance are not required by the Building Code, however these must not take the form of Building Code Letters of Assurance.

When are Letters of Assurance Required for Part 9 Buildings?

Subsection 2.2.7.1. in Part 2 of Division C of the 2018 BC Building Code and Subsection 2.2.7.1. in Part 2 of Divisions C of the Vancouver Building By-Law 2019 outline the requirements for Letters of Assurance in their respective jurisdictions. Part 3 buildings and Part 9 buildings have different requirements for Letters of Assurance, and it is not uncommon for Letters of Assurance to be requested by the Authority Having Jurisdiction (AHJ) for Part 9 Buildings when it is not in the actual scope of requirement.

2024 BC Building Code Requirements

In the 2024 BC Building Code, Subsection 2.2.7. Professional Design and Review gives the following as the required scope for Letters of Assurance:

2.2.7.1. Application
1) The requirements of this Subsection apply to
a) buildings within the scope of Part 3 of Division B,
b) buildings within the scope of Part 9 of Division B that are designed with common egress systems for the occupants and require the use of firewalls according to Article 1.3.3.4. of Division A, and
c) the following, in respect of buildings within the scope of Part 9 of Division B other than buildings described in Clause (b),
i) structural components that are not within the scope of Part 9 of Division B (See Note A-2.2.7.1.(1)(c)(i).),
ii) geotechnical conditions at building sites that fall outside the scope of Part 9 of Division B,
iii) sprinkler systems designed to NFPA 13, “Installation of Sprinkler Systems”, and
iv) standpipe and hose systems designed to NFPA 14, “Installation of Standpipe and Hose Systems”.

Note A-2.2.7.1.(1)(c)(i) Structural Components. The reference to “structural components of buildings that fall within the scope of Part 4” includes the situation where a building is classified under Part 9 due to its size and occupancy but also contains some structural components (such as beams supporting concentrated loads) which must be designed under Part 4. In this situation only Schedules B and C-B for the structural components are required. Schedule A and Schedules B, C-A and C-B relating to non-structural components are not required.

Vancouver Building By-Law 2019 Additional Requirements

The Vancouver Building By-Law 2019 adds the following requirements to the requirements above (in blue italics):

2.2.7.1. Application
iii) sprinkler systems designed to NFPA 13, “Installation of Sprinkler Systems”, NFPA 13R, “Installation of Sprinkler Systems in Low-Rise Residential Occupancies”, or NFPA 13D, “Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes”, and
iv) standpipe and hose systems designed to NFPA 14, “Installation of Standpipe and Hose Systems”,
d) a building that is designed according to Article 1.3.3.5. of Division A,
e) a building that is within the scope of Part 5* of Division B,
f) additions which are subject to Part 11 of Division B, and
g) a change of major occupancy which is subject to Part 11 of Division B.

*Part 5 Environmental Separation-Building Envelope

The Guide to Letters of Assurance states the following about the requirement for Letters of Assurance for Part 9 Buildings:

14. Application of Letters of Assurance to Part 9 Housing and Small Buildings

Letters of Assurance are generally not intended to apply to Part 9 buildings, although authorities having jurisdiction often elect to utilize them. Only those Part 9 buildings or their components that fall within the scope of Subsection 2.2.7. in Part 2 of Division C are required to be subject to Letters of Assurance.

Clause 2.2.7.1.(1)(c) describes the parameters when registered professionals and Letters of Assurance are required for certain components within Part 9 buildings (e.g. structural, geotechnical, sprinkler systems and standpipe systems).

Note that Article 2.2.7.1. of the VBBL 2019 includes many additional conditions when registered professionals are required on a building projects, including Part 9 buildings.

Refer to the Joint Professional Practice Guidelines – British Columbia Building Code Letters of Assurance Requirements for Part 9 Buildings (AIBC and Engineers and Geoscientists BC 2021) for further information.

For example, Letters of Assurance are required for a structural component (in a Part 9 building) that falls within the scope of Part 4 of Division B. Letters of Assurance are required for that structural component only. Beams with point loads, girder trusses, trusses with spans greater than 12.2 meters and proprietary engineered products are some examples of structural components that may exceed the scope of Part 9 of Division B and will require a registered professional to assume responsibility for the substantial Building Code compliance of such components.

If a Part 9 building contains numerous Part 4 components, many authorities having jurisdiction require that the scope of the Letter of Assurance include the integrated structural design and field review for the entire building. The registered professional of record should review with the authority having jurisdiction the local requirements for such circumstances.

If a registered professional is taking responsibility for specific components within a Part 9 building, the Schedule B should be clearly annotated to describe the applicable components.

14. 1 Factory-Built Roof Trusses

Factory-built roof trusses that are designed under Article 9.23.14.11. in Part 9 of Division B of the Building Code do not require Letters of Assurance from the truss designer. However, in some cases authorities having jurisdiction request a written commitment from a registered professional that the girder reactions and loads are satisfactory. These written commitments are not required under the Building Code and must not take the form of Building Code Letters of Assurance.

Factory-built roof trusses that do not fall within the limits defined in Article 9.23.14.11. in Part 9 of Division B are within the scope of Part 4 of Division B and do require Letters of Assurance.

14.2 Beams

Uniformly loaded steel beams which can be sized from Table 9.23.4.3. in Part 9 of Division B, and for uniformly loaded glulam beams which can be sized from Table 9.23.4.2.-K of the Part 9 Span Tables do not require Letters of Assurance from the beam designer. In some cases, authorities having jurisdiction request a written commitment from a registered professional that the beams have been designed according to Tables 9.23.4.3. and 9.23.4.2.-K. These written commitments are not required under the Building Code and must not take the form of Building Code Letters of Assurance.

Beams with non-uniform or concentrated loads fall within the scope of Part 4 of Division B and require Letters of Assurance.

14.3 Alterations

Alterations to Part 9 buildings, particularly to commercial buildings that are subject to changes of use or occupancy, may sometimes trigger the need for Letters of Assurance. More information on the possible implications of building alterations is provided in 19 Application of Letters of Assurance to Building Alterations and Tenant Improvements.

Letters of Assurance for Geotechnical Components

Letters of Assurance for Geotechnical Components are required only if the geotechnical conditions fall outside the scope of Part 9 Division B. Therefore, a Geotechnical Engineer may be contracted to do an investigation of the soil, but would only provide Letters of Assurance if the following conditions are found (See A Guide to Letters of Assurance Section 17):

• the allowable bearing pressure is less than 75 kPa (1566 psf)
• foundations that are supported on permafrost
• foundations that may be subject to slope instability
• shoring
• underpinning
• deep foundations
• foundation walls that exceed the criteria of Subsection 9.15.4. in Part 9 of Division B, or
• retaining walls, other than foundation walls, that are critical for the support of building foundations and are considered to be structural elements of the building as described in the Division B - Notes to Part 9 Housing and Small Buildings, Sentence A-9.3.2.9.(4)

Summary

In summary the use of Building Code Letters of Assurance for Part 9 buildings is limited. If your local Authority Having Jurisdiction is requiring Letters of Assurance beyond what is prescribed in the BC Building Code or the Vancouver Building By-Law we would recommend having the engineer contact EGBC to confirm whether a Letter of Assurance is required and have a further discussion with the AHJ.

Sprinkler Systems in Part 9 Buildings

As noted in the different requirements between the BC Building Code and the Vancouver Building By-Law, the trigger for requiring Letters of Assurance for sprinkler systems is different.

The BC Building Code only requires Letters of Assurance for sprinkler systems designed to NFPA 13, these sprinkler systems are generally intended for buildings taller than four stories in building height or buildings of high hazard industrial use. There is no requirement for Letters of Assurance to be issued for the design of NFPA 13R or NFPA 13D sprinkler system designs.

The Vancouver Building By-Law differs in that it requires Letters of Assurance for all sprinkler systems regardless of their application.

(Are sprinkler systems required to be designed by a registered professional?)

Summary of BC Building Code Sprinkler System Design Requirements

NFPA 13 “Installation of Sprinkler Systems.” Applies to all buildings requiring sprinkler systems other than those provided below as 13D or 13R designs.
NFPA 13R “Installation of Sprinkler Systems in Low-Rise Residential Occupancies”
a) Group C buildings containing no other major occupancy that is not more than 3 storeys in building height and conforms to BCBC 9.10.1.3. or
b) In a building of care occupancy with not more than 10 occupants that is not more than 3 storeys in building height and conforms to one of BCBC Articles 3.2.2.42. to 3.2.2.46.
NFPA 13D “Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes”
a) in a building of residential occupancy throughout that contains not more than 2 dwelling units, or
b) in a building of care occupancy, provided i) it contains not more than 2 suites of care occupancy, ii) it has not more than 5 residents throughout, and iii) a 30-minute water supply demand can be met.

This is a summary of the BC Building Code requirements as it pertains to Part 9 buildings only, please refer to BC Building Code 2018 Division B Section 9.10.1.3.(8) and 3.2.5.12. for complete details and requirements

Standpipe and Hose System Design Requirements

According to the 2024 BC Building Code a Standpipe System designed to NFPA 14 is required as shown below.

3.2.5.8. Standpipe Systems
1) Except as permitted by Sentence 3.2.5.9.(4), a standpipe system shall be installed in a building that is

a) more than 3 storeys in building height,
b) more than 14 m high measured between grade and the ceiling of the top storey, or
c) not more than 14 m high measured between grade and the ceiling of the top storey but has a building area exceeding the area shown in Table 3.2.5.8. for the applicable building height unless the building is sprinklered throughout.

See also Table 3.2.5.8. (All building sizes requiring standpipes are outside of Part 9)

3.2.5.9.(4) A standpipe need not be installed in a storage garage conforming to Article 3.2.2.90., provided the building is not more than 15 m high.

References

A Guide to Letters of Assurance Section 6.3.1 states that an AHJ may not require a coordinating registered professional for Part 9 Buildings under certain circumstances.

“Some authorities having jurisdiction may not demand a coordinating registered professional when the project involves a single registered professional of record…”
”Some authorities having jurisdiction may not demand a coordinating registered professional for Part 9 buildings when the project involves more than one registered professional of record, provided the disciplines involved do not require coordination (e.g. a structural engineer and a fire suppression engineer)…”
”Some authorities having jurisdiction may not demand a coordinating registered professional for Part 9 buildings when the project involves more than one registered professional of record even though coordination is required of such disciplines (e.g. structural engineer and geotechnical engineer). Coordination between these disciplines is part of normal professional practice…”

The coordinating registered professional is responsible for coordinating design and field reviews by all the various registered professionals of record. The coordinating registered professional is either an Architect registered with AIBC or an Engineer registered with EGBC. Building Designers do not act as a coordinating registered professional. (Note: A Guide to Letters of Assurance Section 6.3.1 states that an AHJ may not require a coordinating registered professional for Part 9 Buildings under certain circumstances.)

Registered professionals are registered either as an Architect with AIBC or an Engineer with EGBC. Building Designers are not permitted or required to issue Letters of Assurance.

Guide to Letters of Assurance

The Guide to Letters of Assurance Version 6.1 authored by the Building & Safety Standards Branch is an outstanding resource to guide professionals and authorities having jurisdiction in the proper use of Letters of Assurance. It is strongly recommended that all professionals and officials involved in design, permitting, and construction of buildings in BC familiarize themselves with the contents of this guide.