EPISODE: 017 - APPROVED DOCUMENT B - FIRE SAFETY - PART 4 OF 4

BYTNAR - TALKS

EPISODE 017 - APPROVED DOCUMENT B - FIRE SAFETY - PART 4 OF 4

This episode is for people who want to know more about Approved Document Part B – Fire Safety.

You should like this episode if you ask yourself questions like:

• What are the vehicle access requirements for fire safety in dwellinghouses under Approved Document B?

• How close should a fire main be to a fire appliance according to UK Building Regulations?

• What are the standards for dry and wet fire mains in high-rise buildings?

• What is REI120 and REI60 in fire safety enclosures, and when are they required?

• How should smoke and heat be ventilated from basements in residential buildings?

• What is the maximum allowable hose distance for firefighting operations in buildings?

• How do I design fire safety information plans for compliance with Section 17?

• What are the guidelines for turning facilities for fire vehicles on residential properties?

• What are the fire safety requirements for high-rise buildings over 18 meters in height?

LET'S TALK ABOUT YOUR PROJECT

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This is Bytnar Talks – The Engineer Takes on Construction, Episode 17.

Hi, I'm Piotr Bytnar. Each day I help my clients plan and design building projects through Bytnar Limited, a consulting Chartered Structural Engineers practice.

My biggest passion — and the cornerstone on which I've built my business — is finding clever solutions for construction projects.

I am a Chartered Structural Engineer and a budding software developer, so you can rest assured that I will strive to talk about the best practices and the use of new technologies in the industry.

And if you're embarking on a construction project or are involved in planning, designing, and building the world around us, you'll find this podcast useful.

Approved Document B – Fire Safety: Part Four

Hi there, and welcome to Bytnar Talks, your favorite podcast on all matters of architecture, engineering, and construction.

It is Thursday, the 23rd of May, 2024, and I'm here back with you for the 17th episode, with further information on fire safety in dwellings.

Today, I’ll close this part of the consideration of fire safety in buildings, and we’ll move to Volume Two, which deals with all other buildings, in subsequent episodes.

Last week, in Episode 16, I talked about Requirements B3 and B4, covering Sections 5 to 12.

I told you about Requirement B3, which deals with building stability during a fire event.I also discussed measures to inhibit fire spread, both within the building and between separate structures — that is, Requirement B4.

That requirement mandates:

• Subdivision of buildings with fire-resistant construction, and

• Installation of automatic fire suppression systems, where necessary.

Additionally, it requires the inhibition of unseen fire and smoke spread within concealed spaces, putting extra attention on cavity barriers and fire-stopping wherever needed.

In this episode, I will cover:

• Requirement B5,

• Mention the requirements of Regulation 38, and

• Tell you what you can find in the Appendices.

This episode will cover the aspects of:

• Necessary provisions for the event of fire, and

• Required information for the safe management, maintenance, and operation of the building,

• As well as preparation for the event of fire.

So without further ado, let’s dive into the fire safety Requirement B5, Regulation 38, and Appendices A–G, as treated in the Approved Document. 🎵 [Music] 🎵

Today, I’ll tell you a bit about Requirement B5, Regulation 38, and what you can find in the Appendices of the Approved Document.

In the gist, we need to provide:

• Enough appropriate space and access for the fire and rescue teams, to allow unhindered operation, and consider feasible distances for the fire operation — like hose length or adequate water pressure to serve the building.

There are provisions within the document dealing with:

• Typical fire safety installations and equipment.

However, some consultation with the local fire brigade may be necessary,as the equipment and approach vary from district to district.

In this episode, you’ll find out:

• What to take into consideration when approaching the firefighting and rescue operation requirement of the building regulations,

• What to think about when designing and operating the building, and

• What sort of scope of information provision should be in place following the completion of the build or at the first occupation of the building,

  
  

  to allow for a well-informed reaction in the event of fire.

All right — let’s get on to it, shall we?

Requirement B5 – Access and Facilities for the Fire Service

Let’s start with what the legislation actually requires of us in its wording:

Requirement B5 contains two key points:

Point One:The building shall be designed and constructed so as to provide reasonable facilities to assist firefighters in the protection of life.

Point Two:Reasonable provisions shall be made within the site of the building to enable fire appliances to gain access to the building.

Relatively simple, right?

So what does that mean in real terms?

Of course, the width and breadth of the approach will depend on the type and size of the building.It is understood that most of the firefighting will happen within the building, therefore:

• There should be enough provision for the safe execution of a firefighting operation inside the building,

  
  

  including smoke and heat ventilation, where appropriate.

• There should also be enough space near the building to enable the operation of fire appliances.

• And, finally, there should be enough information available about the building to allow firefighting men and women to appropriate assessment before they go inside and risk their life saving yours

Section 13 – Vehicle Access in Dwelling Houses

Vehicle access should be provided close enough to the building so it can serve in the event of fire.The general requirement is a maximum distance of 45 metres for the pumping appliance, so the hose can reach the furthest point in that building that it is trying to save.

The access doors should be at least 750 mm wide to allow uninhibited entry for the firefighters.

In Flats, however, there are two separate options to choose from:

1. Similar provision to dwelling houses — with an opening of at least 750 mm wide, which is universal and mandatory.

2. If the block of flats is small enough to allow external pumping, then that is acceptable — with a hose reach distance of 45 m.

If the elevation is long enough, doors may need to be provided every 60 m, measured from centre to centre or from the edges of the building.There must be sufficient access to allow effective firefighting operations, including enough entry points into the building.

Alternatively, the building can be served by fire mains, which come in two types:

• Dry riser, or

• Wet riser.

For a dry fire main, the pumping appliance should be no further than 80 m from the inlet, and that inlet must be clearly visible from the parking position of the appliance.It must comply with Section 8 of British Standard 9990.

A wet riser requires similar provisions — 80 m maximum distance to the entrance, inlet clearly visible, and a clear path to the suction tank inlet, in case it needs to be refilled.

Hard standings and roads should also comply with regulations. Notably:

• Access roads should not require reversing more than 20 m. If so, turning facilities must be provided.

• The road must withstand an axle load of 12.5 tonnes as standard, or 17 tonnes if the fire appliance needs to traverse a bridge.

Section 14 – Fire Mains and Hydrants in Flats

So, what is a dry and wet fire main, you ask?

• A dry riser is empty inside and is supplied with water by the firefighters' pump at the scene.

• A wet riser is already full of water, typically from its own tank, but inlets must be provided to replenish the tanks when needed.

Fire mains should be located within:

• Firefighting shafts,

• Protected stairways, or

• When those are not available, provided separately if there is no vehicle access to the building.

In any case, the maximum hose distance from the outlet must be:

• 45 m if there are no sprinklers,

• 60 m if sprinklers are present.

If the layout of the building is not yet known during design, the maximum distance should be calculated as two-thirds of the on-plan diameter of a circle representing the floor plan area.

There is a limit to the vertical reach of fire mains, which is 50 m above the vehicle access level.This is to ensure host pressure does not exceed 10 bars:

• 5 bars to reach the height (50 m),

• 5 bars residual pressure to fight the fire effectively at the top.

The fire main system and hydrants are discussed in more detail in British Standard 9990.

A building may require additional private hydrants if it is:

• More than 100 m from an existing public hydrant, or

• Has a floor area exceeding 280 m².

If the water supply is insufficient, an alternative supply may be required — such as a tank, river, or other water source — but it must be capable of supplying 45,000 litres of water at any point, and is subject to consultation with the local fire service.

Section 15 – Access to Buildings for Firefighting Personnel in Flats

Generally, for low-rise buildings with no basement, access is achieved through:

• Front doors, and

• Protected stairways.

For high-rise buildings, with storeys over 18 m in height above vehicle access level, the building should have:

• One or more firefighting shafts,

• Each shaft must include a firefighting lift.

In any case, we are talking about:

• REI 120 for the shaft enclosure — meaning 2 hours of resistance, and

• REI 60 for any separation within the shaft from habitable areas.

This means the firefighting shaft must:

• Be impenetrable to fire for at least 120 minutes, and

• Remain structurally stable, while the inner compartments maintain separation of 60 minutes.

part of the building, and separation within the enclosure — between stairs and lobby, and lift doors — in this construction should be subsequently considered as either E60 or E30.

So:

• E60 for two-hour construction (walls and enclosure), and

• E30 in 60-minute enclosure areas.

Additional consideration for basements and the protected shaft should be provided when:

• The lowest basement storey is more than 10 m below the vehicle access point,

• And must include a firefighting lift, or

• For large basements of minimum 900 m² per storey, having two or more storeys.

However, it does not require a firefighting lift until it meets the condition of being deeper than 10 m.

In fire-shafted buildings, an additional shaft needs to be considered if:

• There are floors at levels over 18 m above the fire and rescue vehicle access level, or

• There are storeys over 900 m² in floor area.

It is important to keep the firefighting shaft isolated from the remaining part of the building, and to allow for ventilation of heat and smoke, so it can remain operational for the duration of the fire event.

It must also have fire mains with outlets and valves at each storey.

There are rules for rolling shutters, which must remain operational without the need for ladders (or "l ers" — presumed typo for ladders).

Clear signage should be provided for buildings with storeys over 11 m from ground level.

An evacuation alert system will be required in blocks of flats with a top storey over 18 m above ground level.

Secure information boxes should be provided for blocks of flats over 11 m above the ground floor level, so that the firefighting crew can access critical information immediately.

Section 16 – Venting of Heat and Smoke from Basements in Flats

Basement storeys and compartments should be ventilated and provided with heat and smoke removal systems.

When the basement is:

• Shallow (less than 3 m),

• And small (less than 200 m² in footprint),

• And the rooms have windows and doors,

Then special ventilation arrangements are not required, since it can be easily ventilated via those openings.

Strong rooms (e.g. safe rooms in banks) do not require smoke outlets.These are heavily protected rooms designed to remain secure in extreme conditions.

Natural smoke outlets should:

• Be distributed around the perimeter of the basement, room, or enclosure,

• Be located at the high level of the space they serve, and

• Be at least 2.5% of the floor area of the space they serve,

• Be unobscured, or

• Clearly signed and accessible,

• And kept away from escape routes.

If we install mechanical extraction, this can be provided for basements with sprinkler systems installed, but it must meet sufficient standards.

“Sufficient standard” means:

• 10 air changes per hour,

• 300°C gas resistance for 60 minutes, and

• Automatic activation.

Ducting should:

• Be Class A1 fire-rated, and

• Be separated if it serves separate compartments or storeys.

Section 17 – Regulation 38: Fire Safety Information

This brings us to the final section, Section 17, which extends on Regulation 38 — Fire Safety Information.

So, what does the legislation say?

Regulation 38 has three main points:

Point 1:This regulation applies where building work:

• (a) consists of or includes the erection or extension of a relevant building, or

• (b) is carried out in connection with a relevant change of use of a building, and

• Part B of Schedule 1 imposes a requirement in relation to the work.

Point 2:The person carrying out the work shall give fire safety information to the responsible person,no later than:

• The date of completion of the work, or

• The date of occupation of the building or extension —

  
  

  whichever is earlier.

Point 3:In this regulation, “fire safety information” means:

Information relating to the design and construction of the building or extension and the services, fittings, and equipment provided in or in connection with it, which will assist the responsible person to operate and maintain the building or extension with reasonable safety.

Definitions:

• (b) “Relevant building” means a building to which the Regulatory Reform (Fire Safety) Order 2005 applies, or will apply after the completion of the building works.

• (c) “Relevant change of use” means a material change of use where, after the change, the Fire Safety Order will apply or continue to apply.

• (d) “Responsible person” has the meaning given in Article 3 of the Regulatory Reform (Fire Safety) Order 2005.

In essence, it is all about ensuring that for any relevant building, sufficient fire safety information is handed over to the person responsible — so that the building can be safely managed after completion, operated and maintained as necessary, and that the fire safety strategy is known.

Information will need to cover the typical aspects of the building’s fire safety, such as:

1. An as-built plan, showing:

   • Escape routes, including exit capacity per storey in the building,

   • Location of fire-separating elements,

   • Fire doorsets,

   • Location of detection devices, alarms, firefighting equipment, and sprinkler systems,

   • Valves and control equipment for sprinklers,

   • Smoke control systems, their modes of operation, and control systems,

   • Identification of high-risk areas.

2. Specification of fire safety equipment and their maintenance schedules.

3. Assumptions regarding the management of the building.

4. Any provisions for the evacuation of disabled people.

This is a general provision that will be expanded in high-risk or complex buildings, and enhanced with a detailed fire safety strategy, which includes:

• Procedures for operating and maintaining fire protection measures, and

• An outline cause and effect matrix for the building — essentially giving the responsible person an understanding of different fire scenarios and how they should be responded to.

And finally,

5. All the general information, including minute technical details, should be made available.

So, that’s it for the Requirement.

Now, why don’t we skim through the Appendices, shall we?

• Appendix A is a Glossary of Terms.

  
  

  There are many you may not be familiar with — so this is the go-to section for definitions.

• Appendix B offers explanations for abbreviations and codes used throughout the document —

  
  

  For example, all your A2-s1, d0, B ROOF(t4), and REI ratings are explained here.

It also outlines:

• Required fire resistance of building elements based on position and building type,

• Minimum periods of fire resistance based on Purpose Group classification,

• Guidance on how to apply these, and

• Limits on uninsulated glazing used on escape routes.

• Appendix C covers fire door expectations.

• Appendix D explains measurements used in the document —

  
  

  Including how to measure clear openings, escape route widths, etc.

• Appendix E addresses considerations involving sprinklers.

• Appendix F lists all the standards referred to in the document —

  
  

  Including BS 9990 and other key standards regulating materials, testing, design, and specification of all fire safety elements.

• And finally, Appendix G lists all additional relevant legislation and publications the document refers to.

🎵 [Music] 🎵

So here we have it:

Approved Document B, Volume One – done and dusted. ✅

Let’s do a quick recap:

As you can appreciate, the legislation provides comprehensive guidance for building design and construction to:

• Ensure fire safety, and

• Facilitate firefighting operations.

Requirement B5 deals with access and facilities for the fire service, stating that buildings must:

• Offer reasonable facilities for firefighters, and

• Allow fire appliances to access the building.

Adequate internal provisions — including smoke and heat ventilation — are also required.

• Section 13: Vehicle access in houses.

  • Doors must be at least 750 mm wide, and

  • No point in the house should be more than 45 m from a pumping appliance.

For flats, similar access applies — or, alternatively, a fire main system must be provided.

• Dry fire mains should be within 80 m of the appliance, clearly visible from the parking position, and compliant with BS 9990.

• Roads and hard standings must support vehicle axle pressures, and reversing over 20 m must be avoided unless turning facilities are in place.

• Section 14: Fire mains and hydrants.

  • Dry fire mains are supplied by firefighters' pumps;

  • Wet fire mains have internal water tanks.

  • They must be located in protected shafts or stairways.

  • Hose distances must not exceed 45 m (or 60 m with sprinklers).

  • Dry systems must not exceed 50 m above access level to limit pressure to 10 bars.

  • Additional private hydrants are needed if no public hydrant exists within 100 m or for larger buildings.

• Section 15: Access for firefighting personnel.

  • For low-rise buildings, access via front doors and stairways is typical.

  • High-rise buildings (over 18 m) must have firefighting shafts with lifts, with:

    • REI 120 enclosures, and

    • REI 60 internal separation.

  • Basements deeper than 10 m, or of large floor area, also require firefighting shafts and clear signage.

• Section 16: Venting heat and smoke from basements.

  • Small, shallow basements with windows and doors may not need special measures.

  • Natural smoke outlets must be at least 2.5% of the floor area.

  • Mechanical extraction is required in sprinklered basements —

    
    

    providing 10 air changes per hour and 300°C resistance for 60 minutes.

• Section 17: Fire Safety Information under Regulation 38.

  • Live and detailed fire safety information must be passed to the responsible person before completion or first occupation.

  • Must include:

    • As-built plans,

    • Escape routes,

    • Fire-resisting elements,

    • Fire safety equipment,

    • Sprinkler system details,

    • Maintenance schedules,

    • Evacuation provisions, especially for disabled occupants.

In the Appendices, you’ll find everything supporting the main text —From glossaries, material classifications, fire door requirements, and measurement rules, to fire resistance standards and legislative references.

Now you can appreciate how these comprehensive requirements ensure that buildings are designed, constructed, and maintained in a way that facilitates effective firefighting and occupant safety.

In the next episode, we move on to Volume Two of Approved Document B,dealing with buildings other than dwellings. 🎵 [Music] 🎵

I hope you enjoyed this episode and that the fire safety considerations of Requirement B5 and Regulation 38 are now more clear and comprehensible to you.

If you have any questions, reach out to me on LinkedIn, or send me an email — I’m more than happy to help you out.

At Bytnar, we deal with planning, designing, and managing your projects.We are always glad to offer a free initial consultation to steer you in the right direction.

Visit www.bytnar.co.uk for non-obligatory help.

At Bytnar, we help our clients design and execute their dream homes or investments.And if your building is falling apart, we can help investigate the causes and provide an appropriate strategy, design, and specifications for repair.

Thank you again for listening!Please voice your opinions — I’m waiting for you on LinkedIn, and I want to hear from you.

See you next week, and remember:

Bytnar designs the world around you.

Toodloo! 👋

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Piotr Bytnar BEng (Hons) MSc CEng MIStructE

Chartered Structural Engineer who deals with the Architecture of buildings. His Master's Studies led him to an in-depth understanding of risk and contract arrangements in construction as well as specialist knowledge in soil mechanics.

He and his team help homeowners and property developers to design and deliver construction projects reducing waste in time and the cost. He believes that the construction project is an iterative process that can be well managed and it is best managed if all the aspects of the project definition and management are dealt with in-house or coordinated by one organisation. His team works to all stages of RIBA and ISTRUCTE stages of work and enables contractors to deliver projects on-site providing risk evaluations, methodologies for execution of works and temporary works designs.

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