BYTNAR - TALKS
EPISODE 018 - APPROVED DOCUMENT B - FIRE SAFETY - VOLUME II - PART 1 OF 2
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 fire safety requirements for non-dwelling buildings under Approved Document B Volume II?
How are fire detection and alarm systems classified for non-residential buildings?
What is the purpose of horizontal escape routes in fire safety planning for office buildings?
What considerations are there for vertical escape design in high-rise office buildings?
What are the simpler fire safety provisions for small premises under 280m²?
How should internal linings be classified to resist flame spread in commercial buildings?
What alternative approaches are allowed for fire safety compliance in non-dwelling buildings?
How should mixed-use buildings handle fire safety regulations across different purpose groups?
What are the special fire safety requirements for healthcare and institutional buildings?
This is Bytnar Talks the Engineer Takes on Construction Episode 18 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 cornner tone on which I've built my business is find finding clever solutions for construction projects I am a chartered structural engineer and a bing 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 approv document B fire safety volume two part one hi there and welcome to bitnar talks your favorite podcast on all matters of architecture engineering and construction it is Thursday the 30th of May 2024 and I'm here back with you with the 18th episode and further information on fire safety in dwellings today I'll move along to volume two of the approved document B and talk about the distri charg of building regulation concerning buildings other than dwellings last week in episode 17 I talked about the requirement B5 access and Facilities of volume one for the fire service what type of information is required in line with regulation 38 and told you what is hidden in the appendices which are shared between the volumes the episode told you about the consideration and Provisions required for vehicle and Appliance access so that the firefighting crew is able to sufficiently fight the fire provisions and distances of water outlets and backup inlets whether in the form of hydrant or dry or wet fire main I talked about the protected shafts and Provisions for heat and smoke ventilation to basement as well as the required information about the systems layouts construction capacity and strategy is for when the fire breaks out in this episode I will cover requirements B1 means of warning and escape and B2 internal fire spread Linings of the volume two and the introduction to do to the document covering sections 0 to six so without further Ado let's dive into the fire safety requirements B1 and B2 of volume two [Music] now this material is about buildings other than dwellings which consideration is covered in volume two of the approved document B it consists of 20 sections covering guidance on all the requirements of the building regulations and appendices appendices which are mutual for both the volume one dwellings as well Volume 2 buildings or than dwellings so I will not be coming back to them again in this material today I will cover section 0 to6 which will include the requirements B1 means of warning and escape and the requirement B2 internal fires spread Linings I will start with Section zero that covers the general information and the approach that should be taken in consideration whilst using the guidance of the document section one 12 five will cover fire detection and alarm systems horizontal and vertical Escape Routes guidance on small premises and general Provisions whereas section six will cover wall and ceiling Linings it is important to know why and how we should use the guidance and what level of consideration we ought to have When approaching specification and design of buildings other than dwellings what classes of buildings are con considered and how does the specification varies between them all right then so let's dive straight into it shall we this material is about buildings other than dwellings which consideration is covered in volume two of the approved document B it covers guidance on discharging requirements B1 to B5 and regulations 38 of building regulations and describes the assumptions made when forming the guidance mentions of section zero of things like the management of the premise which is not covered in the regulation but the regulation assumes the proper C interations are put in place and maintained by the building owner and where the failure to do so may be prosecuted on the basis of other legislation it needs to be understood that the guidance concentrates on the life safety not the premise protection so further and more stringent approach may be needed to address these aspects the Fire Protection Association would be the best place to go for more information on that the guide is aims to be inclusive so the so to cater for most people in most situations therefore exclusion of the building users should not form part of the considerations except in special cases and there are also there also may be such special cases that the guidance does not cover but the design approach should cater for so don't follow with blindly look at it holistically don't exclude people that use this building and you should be should be good to go as with the previous volume alternative approach to the guidance can be made but will need to be minimum quality minimum equally safe to that contained within the guidance of the approved document and should form a coherent holistic hole some special consideration will be needed for the buildings containing more hazardous operations like battery producers fireworks power plants and whatnot special consideration should follow Health Care premises and the information contained within the Department of Health publication which is called fire code unsupervised group homes should either follow the department of health health technical memorandum 88 dealing with fire precautions in housing providing NHS support in living in the community for small buildings and otherwise treated as a Purpose Group to be shopping complexes or buildings with Atria passing through compartment floors are better treated with approach of the British standard 9999 as are the assembly buildings but some special consideration needs to be taken in line with the safety of the sports grounds act 1975 schools on the other hand are covered in the building buletin 100 special considerations are also due to prisons which are exempt from the consideration of the building regulations but the approach is regulated by separate legislation and the correct approach can be found in the hmpps custodial premises fire safety design guide some leeway can be found When approaching historical buildings but as ever if there is an issue or ambiguity the only solution for the specification may be the approach of the fire safety engineering and guidance covered in British standards 7974 and anciliary supporting published documents I've mentioned the Purpose Group when assigning risk level to the Assisted Living premises that is what purpose groups are for they group typical buildings into risk classifications and there are seven groups total but six in the volume two of the approved documents and these are group two residential where people sleep overnight type A institutional and type B other group three offices group four shop and Commercial spaces group five five assembly and Recreation group six industrial group seven storage and other non-residential which further divides into group 7A any buildings not in group 126 and not 7B and 7B give special provision to car packs for small Vehicles up to 2 and 1/2 ton gross weight as however if there is mixed use in play the consideration should be divided if the auxiliary space is large enough or is between flats and other groups if in doubt use the more stringent approach in complicated circumstances the requirements May well fall outside of the general guidance and the approach of other approved documents and the fire safety engineering principles may be necessary to assure the fire safety so off to our first requirement requirement B1 means of Waring and Escape as however let's start with finding out what the legislation requires Over Us in its Waring so means of warning and Escape B1 the building shall be designed and constructed so that there are appropriate Provisions for the early warning of fire and appropriate means of Escape in case of fire from the building to a place of safety outside the building k capable of being safely and effectively used at all material times it seems to be relatively simple right and the secretary of state is also of simple intention here just as long as there is enough of Waring and safe and well signed Escape Route that people of different capabilities can use uned the requirement is pretty much covered naturally this will mean many different things to many different buildings and their complexity is but that is why there are purpose groups in place to make it a little bit simpler section one deals with the fire detection and alarm systems in the G the alarm needs to be sufficient so if you work in the car garage it's it may be enough to shout that there is a fire in a corner or there's a fire of a car and everyone will know but as we go more complicated more honorous Provisions will need to be put in place fire detection system should be automatic and form controlled networks of Senses either heat smoke gas or radiation or activated through sprinkler system this will be mandatory in residential type scenarios but will follow different consideration in other purpose groups generally speaking if there is a room where people rarely go to where there can be fire and it will inhibit escape from the building the appropriate system should be in place to alarm people of such event or where the building is otherwise secured for entry or has the pressure differential system counteracting counteracting Ingress of smoke into the Escape way such should be provided the selection of system should follow British standard 5839 which categorizes different systems into three different categories LM and P category L is for the protection of Life which further spreads into five levels of of consideration with most stringent being L1 which is a three out system L2 is defined part system L3 L stage warning to allow Escape Route L4 is Escape Route system and L5 specific fire objective category M treats with manual treats on manual fire detection and alarm systems and category p is about property safety further divided into P1 and P2 P1 being installed through the building and P2 installed in the fine parts of the building with the cut catgory in mind it needs to be established what goes where and how the alarm should be sounded which will be different between the stage and simultaneous evacuation plans or where there are large amount of people and where they are not aware how to behave in that building in the event of fire provision for visual alarms for hearing impaired people or personal vibrating paging systems may also be appropriate in certain circumstances in any case the design installation and maintenance of the system as well as its inter face with other systems should be controlled to assure on its reli reliability for certain limits of student Flats accommodation there also should be a separate automatic detection system in each individual flat leaving the alarm consideration behind section two designed for horizontal Escape deals with an immediate Escape Route to the exit or protected stairway the principle of the approach is if anyone gets confronted with fire they can turn away from the fire and Escape safely if the building is not larger than two stories plus a basement story and no story is larger than 280 M squares the building will be considered small and slightly Lux approach can be taken when considering Escape rout we need to consider the number of people needing to vacate the space and their travel dist distance to the nearest exit as well as how many vertical Escape brouts there are so that access is possible for both from from any point of the space Also there need to be a separate Escape Route for dwellings flats and assembly and Recreation spaces in the mix use buildings when it comes to the number of esape routes single routes are allowed with limitation of distance and on the number of people who will have to travel it typically 30 people maximum rooms limits for residential in and institutional and 60 people rooms for bars and assembly places and 60 people maximum occupation for for single story distance limits start at 9 M from the dead end in residential disabled people buildings and place special fire hazards to 60 m in the open air consequent the distances can be extended for escape in more than one direction starting at 80 M to 100 m in the open air There Are Rules how to measure these distances and limits to relative position between the relative Roots like minimum 45° angle between the points of turn and routes to turn of the route to Alternative exits the minimum number of Escape Routes is associated to the number of occupants so one is is enough for 60 people two is enough between 60 and 600 people and three are for more than 600 people in most cases the amount of the Escape Route will be govern by the distance travel though inner rooms are allowed but should either have alternative exits or in line with the limits imposed by the guidance in the gist people should be able to see if the fire starts in the aess room and be able to leave so the room cannot host to many people 30 people in case of residential use and 60 in other cases exits in the central courts should be separated by Corridor or Lobby Escape Route should be away from the openings in the story or does not go through the zone of 4 and 1/2 meter offsetting around the opening access to Alternative story exits can be through protected lobbies but not through the other protected stairway it is also important to separate circulation routes from protected stairways but by at least means of self closing fire doors with automated release mechanisms meaning if there is some sort of circuit failure or an event of fire the doors will be released to enclose the protected stairway stories of mixed use or occupancy of mixed use or occupancy may require require consideration of separation and alternative exits like in case of restaurants or bar or be divided by the at least protected Corridor with Provisions for automatic fire detection and alarm width of Escape Route starts at 750 mm or well 530 if you count the space between fixed storage racking to slightly over 1 m for up to 220 people using the route over this limit the limit of 220 people Trav traversing the exit we need to allow for 5 mm per person for alternative routes we should discount one as it may be blocked so the story may need to use alternative only and that alternative needs to be capable of allowing enough people through similarly for the Final Exit which will need to accommodate the story load of people plus the stairway so how to establish the Lobby exit with well in the worst case scenario it should be of the story exit width summed up with the stairs width but can be smaller in certain conditions and need to follow the formula formula which is basically 75% of the stair width plus 0.5% of the number of people served by that story exit is it corridors need to be protected when serving bedrooms or mixed occupancy and dead ends of more than 2 m depth in other cases where they do not need to be fire rated they need to provide enough division to stop smoke penetration at or over the ceiling level for dead ends corridors of over 4 and a half meter we are guided to provide protected access to the point of alternative exit its access Escape through the external routes or flat roofs is possible with certain limits like if protected protected within 1.8 m of Route horizontally and 1.1 M vertically and of fire rated Construction in case of the roof also the roof route needs to be one of the alternative routes and cannot be specified in residential institutional buildings and where where the me of public use the building special considerations are needed for the buildings where people will need to be assisted to live like in cases of Residential Care Homes where Progressive horizontal evacuation strategy may be needed if the fire code document applies its recommendation should be used instead the phg strategy requires more often compartmentalization to allow increment movement of people from the area with fire to the next compartment bedroom should form compartments as well as auxiliary rooms where the fire can start and the carehouse should be fitted with the highest level of alarm class class L1 in line with bs5839 installation of sprinkler system allows for More Design freedom in this type of circumstances now to section three designed for vertical Escape in the G there needs to be enough STS and of easy use to allow the Escape even for people with restrained Mobility so if the building is fine for use of the single stairway for each story such building can be served by single stairway within the additional limits for vertical Escape Routes generally small and not complicated buildings with story Level under 11 meter over the ground level or small offices up to five stories with stories over the 11 meter having separate Provisions for escape Refuge should be provided at each usable story protected area or via stairway and to meet certain criteria including marking and provision of emergency voice communication systems the width of the escap STS is regulated but will follow the consideration of number of people to be evacuated at modes of evacuation whether simultaneous or stage wave of access doors Purpose Group and so on there is more than one staircase for each EV evacuation scenario one staircase should be incapacitated in any given scenario the calculation of capacities are shown in the approved document additionally rules on the material use typically A2 S3 D2 ladder use single step helico or spiral stairs is also mentioned generally the provision of fire resistant construction of the enclosure should be observed external staircase can be used if there are also internal Alternatives external staircase needs to be positioned within fire protected zone of 1 M down 1.8 m either side and 1.1 m to the top and protected from elements if High than 6 M use of protected lobbies and corridors accessing protected stairways is generally considered a good idea but it does not need to be the case in line with the guidance if the protected stairways are join their enclosures should not be perforated there are some provisions of having access to toilets or reception desk as well as gas installation within those stairways but all these with further considerations interestingly for single protected stairways serving upper floors this need to terminate at the ground level and separate provide separate Provisions should be made for the escape from basement some different approaches should be observed could be observed in section four dealing with small premises the small premise is such of single occupancy of no more than three story including single basement story and a first story and of a size that if not divided would allow clear view of all the parts of the story so taking the limit of 280 M squared Max the area of the story should be generally undivided except for anciliary spaces and Stor rooms which should be fire rated as with any other case maximum travel distances number of staircases and the enclosure is regulated by the guidance in section five which deals with General provision for protected Escape Routes whether horizontal or vertical and service installation the performance for fire resistance and do of the enclosure is available in appendix B and C and glazings that forms part of these enclosures are also treated within the appendices if the glazing unit can provide enough integrity and insulation there is no restriction on its use doors should be easy to use and operate its locking opening and closing mechanisms and to be of appropriate fire rating doors should generally open in the direction of exit and revolving and automatic doors are allowed however alternative Escape or opening needs to be put in place Escape Route should be at least 2 m high but could be a bit less at the door frame in any way should allow easy exit by most people over the surface that does not promote sleep strips and Falls Final Exit should be of the right capacity well lit and signed and inclusive for disabled people requirements for different purpose groups are contained within the guidance some further consideration of placement and protection of protected power Secrets should be given so that so so to mitigate Fair of the system when it comes to lifts it is generally advised not to use them in the event of fire but certain Provisions may be may need to be made and the lift adapted for evacuation or Provisions made for the use of the firefighting lifts for the evacuation lift enclosure and shaft should follow the enclosure requirements dependent on the type and position of the lift as well as the possibility of the spread of smoke through the lift to protect Ed shaft it is advised to have the operating room either at the top of the shaft or separated if the top installation cannot be achieved refused shoots and storage is to be constructed to Bri standard 5906 they should be separated from separated from the other parts of buildings with either Ray 30 for small buildings with top story under 5 m above ground level or rise 60 Construction and to be accessed directly from the open air or through ventilated Lobby walk in and fully enclosed shop rooms should be separated from the retail area with fire resistant construction minimum rate 30 if the Fire Within would impact the means of Escape unless they are fitted with automated fire detection and alarm systems or are fited with sprinklers so this is it with requirement B1 now let's have a look what the legislation prepared for us legislator prepared for us in the requirement B2 internal fire spread Linings so B2 there are two points in the legislation point one further divides into a and b so0 one the in to inhibit the spread of Fire Within the building the internal lining shell a adequately resist the spread of flame over the surface and B have if ignited either a rate of heat release or a rate of fire growth which is reasonable in the circumstances end point two in this paragraph internal Linings means the materials or products used in lining any partition wall ceiling or other internal structure this one is all about assuring that what is put on the wall and ceilings does not fuel the fire and the spread of fire is somehow restricted so section six tells us what wall and ceiling Linings are acceptable the worst classification being DS3 D2 and best bs3 D2 so between medium to very limited contribution to fire material to fire material but smoke droplets could be as heavy as they get some relaxation on parts of the wall can be introduced but with limited area limitation and being the worst case scenario of the S 3d2 similarly with ceiling mention is special Provisions that are made for ceilings in protected stairways consideration of thermoplastic used in Windows and roof lights the use of flight diffusers and the use of suspended or stretched skin ceilings recognizing different limits depending on different types of thermoplastics additionally flexible membrane covering or PTFE based materials are referred to be treated with the approach shown in British standard 7157 or bre report BR 274 the use of insulated cor panels also gets the attention as does the fixings and possible delamination of the panel when [Music] heated so this is it folks first part of the approved document B Volume 2 is under the belt volume two of the approved document B provides guidance on fire safety for non-dwelling buildings focusing on requirements B1 to B5 and regulation 38 of the building regulations the primary concern is life safety not pro property protection the guidance assumes building owners will maintain proper management practices though these are not directly regulated key consideration of their requirements are inclusivity alternative approaches and special consideration for special buildings buildings are classified into six purpose groups for risk assessment group 2 to7 for covering residential institutional and other office shop and Commercial assembly and Recreation industrial storage and other non-residential including car parks for small Vehicles mixed use buildings should apply more stringed measures where necessary complex situation may require fire safety engineering to BS 7974 and auxiliary published documents requirement B1 means of warning and Escape tells out that buildings must have adequate early fire warning system and safe Escape Routes fire detection system should be automated and follow bs5839 standard categorization follows Life protection class L manual detection Class M and protective protection class P in section one fire detection and L systems we find out that system must be appropriate for the building complexity designed installed and maintained in section two designed for horizontal Escape we find out that escape RS must consider occupant numbers travel distances and protections like fire door and corridors there may be special rules applicable to single and alternative Escape Routes inner rooms and protected stairways section three design of vertical Escape tells us that we should take special Provisions for providing sufficient Escape STS that we should identify redundancies of the Escape Route system in any event of fire for section four small premises we find out some special for smaller buildings of up to three stories with one over and one underground and 280 M square of Maximum story floor area and we find out the general Provisions for protected Escape Routes that include fire resistance en closures easy to use doors Final Exit Provisions protected power circuits lifts and refug shoots and how to treat them in the in the bug drop of the regulation the the requirement of the regulation requirement B2 then internal fire spread Linings tells us that the Linings must resist flame spread and maintain reasonable heat release and fire growth rates classifications range from D S3 D2 which are medium contribution to bs3 D2 with limited contribution special considerations are given to thermoplastic materials insulated core panels and their fixings this document ensures non-dwelling buildings are the to essential fire safety standards it emphasizes early warning safe Escape Routes and proper internal lining to inhibit fire spread in the next episode we move to requirement B 3 to B5 and regulation 38 section 7 [Music] to19 I hope you enjoyed this episode and that the consideration of fire safety Volume 2 requirements B1 and B2 are now more clear and comprehendible for 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 in bitna we deal with planning designing and managing of your projects and we are always glad to facilitate a free initial consultation to steer you in the right direction visit www.b now.co and reach out to us whether your question is if we can help you with your project or what should I do we will be able to give you a piece of non obligatory advice at bitna we help our clients design and execute their dream homes or Investments if your building is falling apart we can also help investigate the reasons behind it and to provide you with an appropriate strategy design and specifications for the repair thank you again for listening please voice up 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!
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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