Preparing evidence for the CAS Building Safety section

The Building Safety section of Build UK's Common Assessment Standard (CAS) asks how a construction company demonstrates competence, supervision, coordination and control of work within its role. It is an assessment of organisational arrangements and evidence. Completing it does not replace the legal duties that apply to a project, and an assessor's acceptance is not a building-control approval.

This guide uses the Version 5 question set dated 1 July 2025. Build UK says Version 6 is scheduled for 1 November 2026. If you are submitting after the new version takes effect, use the new question set and assessment body's instructions. The numbered question map below must be reviewed before publication after that transition.

Confirm whether the section applies

Start with the screening questions in the current CAS question set. They ask what work the company performs or intends to perform and whether it involves projects within the relevant building-safety scope. Do not decide applicability merely from whether your company works on a higher-risk building: the questions and exemptions distinguish broader building work, roles and circumstances. Ask the recognised assessment body how to apply an exemption if your activities are unusual.

Current transition rule: Build UK's 23 July 2026 statement says every supplier undergoing CAS certification must successfully complete competence questions 135, 136 and 138 until Version 6 is published, even if it does not have to complete the remaining Building Safety dutyholder questions. Do not treat a Section 7 exemption as an exemption from those three questions.

For England, separate three things in your evidence register:

1. CAS assessment requirement: what the current Build UK question set asks your company to demonstrate.
2. Building regulations duty: what the Building Regulations 2010, including Part 2A on dutyholders and competence, require for your actual work.
3. Project requirement: what the client, contract, building type and design or construction phase require.

These layers overlap but are not identical. The GOV.UK building requirements guidance applies to England and explains the separate building-regulations dutyholder roles. It also notes that those roles differ from the roles under CDM 2015. Do not assume one appointment or certificate automatically fulfils both regimes.

Build a role-based question map

In Version 5, Section 7 starts at question 135. The early questions address how the organisation manages competence evidence for its workforce and key subcontractor roles, and how it gives them suitable supervision, instruction and information. The question set gives examples such as a training needs analysis, skills matrix, qualification records, named supervisors and evidence of actual communications. A policy alone is a weak answer if there is no record showing how it is used.

The later questions ask about cooperation with other dutyholders, product or system issues and the arrangements relevant to the company's declared dutyholder role. Question 142 identifies intended roles, and the follow-on question numbers depend on whether the company acts as contractor, principal contractor, designer or principal designer. Build an evidence index for the role you really undertake. Do not answer as a principal designer or principal contractor simply because the title sounds commercially attractive.

The table is a preparation aid, not a substitute for the current question set or assessor guidance. The CAS document contains conditional exemptions and examples; confirm which apply to your company.

Keep legal claims within England's rules

In England, Part 2A of the Building Regulations 2010 sets competence and organisational-capability requirements for people undertaking building or design work and duties for clients, designers and contractors. The actual obligations depend on the role and work. Higher-risk building work has additional controls. A broad statement that “CAS certification makes us Building Safety Act compliant” is therefore unsound: the certificate does not determine whether each project has been designed, built and controlled in accordance with its applicable requirements.

When describing previous work, show the facts: role held, location, stage, people involved, information exchanged, issue raised and how it was resolved. Do not recycle a generic project story that omits the decision trail. If the evidence contains client-sensitive details, agree a redacted example with the assessment body rather than fabricating an example.

A submission workflow that survives renewal

Assign a named owner for each applicable question. Keep the source file, version, approval date, next review date and the project example linked to the answer. Before submission, have a competent reviewer check that the proposed answer says what the evidence proves and no more. After assessment, log queries and the accepted response. Where arrangements or key personnel change, update the underlying system; do not wait for the next annual CAS cycle to discover the evidence is obsolete.

For a general guide to all ten sections, use our CAS explainer. A buyer verifying a certificate should use the separate CAS buyer check.

Contractor prequalification software may help organise question owners, documents and review dates. Ask any vendor to demonstrate the exact workflow you need. Complys does not issue CAS certification, determine which legal duties apply or approve building work.

Sources and publication gate

• Build UK — current CAS overview: standard owner and version transition.
• Build UK — Version 5 question set: Section 7 questions and conditional exemptions.
• Build UK — Building Safety section statement, 23 July 2026: temporary requirement for all suppliers to complete questions 135, 136 and 138.
• GOV.UK — design and building work guidance: England building-regulations roles and competence.
• Legislation.gov.uk — 2023 England amendment: Part 2A competence and dutyholder provisions.

Publication recheck: This draft is source-grounded to CAS Version 5. Because Build UK has scheduled Version 6 for 1 November 2026, do not release it after that date without checking the published replacement question set, role map and exemptions, then updating the numbered references and metadata date.