Guidance

Assessing safety risks in high-rise residential buildings: a detailed guide

Published 19 September 2023

Applies to England

This guide is for accountable persons of high-rise residential buildings. It helps you to assess building safety risks as set out in the guidance safety case for a high-rise residential building.

The information in this guide does not cover all circumstances or constitute legal advice. It is meant for non-specialists to help you assess the risk of the spread of fire and structural failure. You may need other people with specialist knowledge to help you.

The purpose of assessing building safety risks

Assessing risks, and learning how safety incidents can happen, helps you to understand your building better. You’ll find it easier to decide what to do to prevent building safety incidents or reduce their severity. You may also identify other reasonable steps you can take to reduce the risk further.

Your assessment will help to demonstrate that you understand the risks and manage them effectively.

Risk assessment team

Your team should include people with knowledge and experience of:

• safety management systems
• fire safety
• structural safety

The team may also want to seek specific advice from others such as the Fire and Rescue Service.

What to assess

Different hazards in different areas

Think about the different areas of your building. Consider the different hazards relating to the spread of fire in an individual flat, compared to those in a common area such as a hall, a community room, or a plant room.

Changes to risks during the life of a building

Ongoing risks during occupation differ from risks in a newly constructed building. Risks can change over time and refurbishing your building can affect its risk profile. This means there is an ongoing need to manage your building’s safety risks.

Safety risk scenarios

In your building safety risk assessment consider all potential scenarios for your building. The following list is not exhaustive, and some scenarios are not relevant in every case.

Fire-risk scenarios

Can include:

• single-floor scenarios, where a fire spreads across multiple compartments on a single floor
• between-floors scenarios, where a fire spreads from a single floor to another floor
• multiple-floor or whole-building scenarios, where more than two floors are affected by the fire
• evacuation scenarios, where a failure of evacuation routes turns a fire into a more serious incident
• emergency-response scenarios, where issues such as failure in early detection or access problems, affect the effectiveness of an emergency response
• safety-system scenarios, where a failure of one or more components of the safety systems could allow a fire event to escalate

Structural-risk scenarios

Can include:

• structural collapse of a residential unit or common areas
• multiple-floor collapse
• whole-building collapse
• balconies or suspended walkways
• attached or supported components
• undermining or compromise of foundations
• aggressive conditions due to chemical or biological processes
• specific incidents such as gas explosion or impact damage

Scenario planning

Consider what could happen in different scenarios, such as if:

• measures to manage risks fail
• your assumptions about structural stability are incorrect
• a building safety incident escalates
• if a safety incident happens, what could the impact be on residents and the building

You should include worst-case scenarios. This approach may differ from how you do other risk assessments.

Existing control measures

Once you identify how an incident could occur and what could happen, review what you do to reduce the chances of it happening or its severity; these are your existing control measures. They include the general fire precautions in place under duties set out in the Fire Safety Order.

You should check that any control measures for which you are responsible remain effective and operate as designed.

All reasonable steps

All reasonable steps should be taken to prevent and mitigate building safety risks. What is reasonable depends on the individual circumstances of the building. You should consider:

• measures already in place and how effectively they control building safety risks
• what other measures could be taken and whether they are reasonable

Certain factors will influence whether measures are reasonable. For example, whether they may create additional risks or are disproportionately expensive.

Risk assessment methods

The Building Safety Act does not require you to use a specific risk assessment method. The one you currently use may be suitable, and you should refer to work that has been done by the Responsible Person or Duty Holder under the Fire Safety Order.

The risk assessment method you use should be fit for purpose and match the risk profile of your building. The scale of assessment needed depends on the complexity of the building being assessed. Whichever one you choose it should consider the full range of risks throughout your building. You could use the example of the HAZID risk assessment method in this guide, to help you understand how a systematic risk assessment can help you.

Example of the HAZID risk assessment method 

We do not recommend any specific risk assessment methodologies but HAZID (hazard identification) is relatively straightforward and may be suitable.

The HAZID method is also known as the ‘what if’ study. It is a systematic process of hazard identification, usually performed by a team of people with a range of skills, knowledge, and experience.

In the ‘what if’ approach, team members are encouraged to explore all eventualities. They do this by asking questions such as ‘what if’ or ‘how could’ about the item or area under consideration.

In answering the questions, the hazards and how they may develop should be explored. The group can then consider who, and how many, could be affected, along with the control measures in place to prevent and mitigate the occurrence.

Structure of a HAZID team

The team is key to the success of a HAZID. A range of relevant expertise is essential. The team should include people with knowledge of:

• details of the building being assessed, including its construction and any subsequent refurbishments or modifications
• the resident profile of the building
• fire safety
• structural safety
• the use of other parts of mixed-use buildings, such as retail or offices
• the maintenance regimes for the building
• the safety management system as covered in the building safety guides for accountable persons
• an overview of the maintenance regimes and safety management systems of other accountable persons

The session facilitator and recorder should have risk assessment and management expertise, with experience of HAZID.

Stages of the process

Divide the building into areas for assessment. Do this before the HAZID study or as part of the first session to encourage full ownership of the process.

How the building is divided up will depend on its design and use. Potential options include:

• by control, in buildings with multiple accountable persons
• by blocks or cores where these have been designed as the building system
• into floors, grouping identical floors for consideration together
• by function, dwellings or utilities for example
• a combination, having regard to any unusual or unique features

No matter how the building is divided, the study team will need to consider any interactions between functions or areas.

Conducting the HAZID

HAZID sessions should be time-limited to maintain the focus of the team. It is likely you will need several sessions to assess a whole building.

For each session:

• the team should be introduced to the parts of the building being assessed
• the team should be provided with a description of the part of the building being assessed, including plans, resident profile and its accountable person
• the facilitator should encourage the team to ask questions to identify how building safety risks might occur, how they could develop and what the consequences could be
• the recorder, with the support of the facilitator, should write down the important points covered in the discussion
• recommendations should be recorded for later consideration
• when the risks have been identified, they should be ranked and prioritised

Record your assessment

Keep a record of your building safety risk assessment. Keep track of any actions or recommendations until they are done, and store and maintain any new information. If you identify additional measures but do not think they are reasonable, provide an explanation.