Section B1 Means of warning and Escape

  1. The Requirement
    1. B1 Guidance
      1. Performance
        1. Introduction
          1. Analysis of the problem
            1. Security
              1. General
              2. B1 Section 1
                1. Introduction
                  1. General
                    1. Large houses
                      1. Material alterations
                        1. Power supplies
                          1. Design and installation of systems
                          2. B1 Section 2
                            1. Introduction
                              1. Provisions for escape from the ground storey
                                1. Provisions for escape from upper floors not more than 4.5m above ground level
                                  1. Provisions for escape from upper floors more than 4.5m above ground level
                                    1. General provisions
                                      1. Emergency egress windows and external doors
                                        1. Inner Rooms
                                          1. Balconies and flat roofs
                                            1. Galleries
                                              1. Basements
                                                1. Cavity Barriers
                                                  1. External Escape stairs
                                                    1. Air circulation systems in houses with a floor more than 4.5m above ground level
                                                      1. Passenger Lifts
                                                      2. Work on existing houses
                                                        1. Replacement windows
                                                            1. Material alterations

                                                          The Requirement

                                                          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 capable of being safely and effectively used at all material times. (a) 1952 C.52; Section 33 was amended by Section 100 of the Criminal Justice and Public Order Act 1994 (C.33) and by S.I. 1963/597. Limits in application Requirement B1 does not apply to any prison provided under Section 33 of the Prison Act 1952(a) (power to provide prisons, etc.).

                                                          B1 Guidance

                                                          Performance

                                                          In the Secretary of State’s view the Requirement B1 will be met if:

                                                          1. there is sufficient means for giving early warning of fire for persons in the building;
                                                          2. there are routes of sufficient number and capacity, which are suitably located to enable persons to escape to a place of safety in the event of fire; and
                                                          3. the routes are sufficiently protected from the effects of fire, where necessary.

                                                          Introduction

                                                          B1.i     These provisions relate to building work and material changes of use which are subject to the functional requirement B1; they may therefore affect new or existing buildings. They are concerned with the measures necessary to ensure reasonable facilities for means of warning and escape in case of fire. They are only concerned with fire precautions where these are necessary to safeguard escape routes. They assume that in the design of the building, reliance should not be placed on external rescue by the fire and rescue service nor should it be based on a presumption that they will attend an incident within a given time. This Approved Document has been prepared on the basis that, in an emergency, the occupants of any part of a building should be able to escape safely without any external assistance. It should also be noted that the guidance for a typical one or two storey dwellinghouse is limited to the provision of smoke alarms and to the provision of openable windows for emergency egress.

                                                          Analysis of the problem

                                                          B1.ii The design of means of escape and the provision of other fire safety measures, such as smoke alarms, should be based on an assessment of the risk to the occupants in the event of fire. The assessment should take into account the nature of the building structure; the use of the building; the potential of fire spread through the building; and the standard of fire safety management proposed. Where it is not possible to identify with any certainty any of these elements, a judgement as to the likely level of provision must be made. B1.iii Fires do not normally start in two different places in a building at the same time. Initially, a fire will create a hazard only in the part in which it starts and it is unlikely, at this stage, to involve a large area. The fire may subsequently spread to other parts of the building, usually along the circulation routes. The items that are the first to be ignited are often furnishings and other items not controlled by the Building Regulations. It is less likely that the fire will originate in the structure of the building itself and the risk of it originating accidentally in circulation areas is limited, provided that the combustible content of such areas is restricted. B1.iv The primary danger associated with fire in its early stages is not flame but the smoke and noxious gases produced by the fire. They cause most of the casualties and may also obscure the way to escape routes and exits. Measures designed to provide safe means of escape must therefore provide appropriate arrangements to limit the rapid spread of smoke and fumes

                                                          Criteria for means of escape
                                                          B1.v The basic principles for the design of means of escape are:
                                                          1. that there should be alternative means of escape from most situations;
                                                          2. where direct escape to a place of safety is not possible, it should be possible to reach a place of relative safety, such as a protected stairway, which is on a route to an exit, within a reasonable travel distance; and
                                                          3. in certain conditions, a single direction of escape (a dead end) can be accepted as providing reasonable These conditions depend on the use of the building and its associated fire risk, the size and height of the building, the extent of the dead end and the numbers of persons accommodated within the dead end.
                                                          The ultimate place of safety is the open air clear of the effects of the fire. B1.vi For the purposes of Building Regulations, the following are not acceptable as means of escape:
                                                          1. lifts (except for a suitably designed and installed evacuation lift);
                                                          2. portable ladders and throw-out ladders; and
                                                          3. manipulative apparatus and appliances, g. fold-down ladders and chutes.
                                                          Note: The regulations would not prohibit the use of such measures as an additional feature but they are not considered suitable as an alternative to adequate means of escape.
                                                          Unprotected and protected escape routes
                                                          B1.vii The unprotected part of an escape route is that part which a person has to traverse before reaching either the safety of a final exit or the comparative safety of a protected escape route, i.e. a protected corridor or protected stairway. Unprotected escape routes should be limited in extent so that people do not have to travel excessive distances while exposed to the immediate danger of fire and smoke. Even with protected horizontal escape routes the distance to a final exit or protected stairway needs to be limited because the structure does not give protection indefinitely. B1.viii Protected stairways are designed to provide virtually ‘fire sterile’ areas which lead to places of safety outside the building. Once inside a protected stairway, a person can be considered to be safe from immediate danger from flame and smoke. They can then proceed to a place of safety at their own pace. To enable this to be done, flames, smoke and gases must be excluded from these escape routes, as far as is reasonably possible, by fire-resisting construction and doors or by an appropriate smoke control system, or by a combination of both of these methods.

                                                          Security

                                                          B1.ix The need for easy and rapid evacuation of a building in case of fire may conflict with the control of entry and exit in the interest of security. Measures intended to prevent unauthorised access can also hinder entry of the fire and rescue service to rescue people trapped by fire. Potential conflicts should be identified and resolved at the design stage and not left until after completion of the work. The architectural liaison officers attached to most police forces are a valuable source of advice. This document does not intend for the types of lock used on windows (see paragraph 2.8) and entrance doors to dwellinghouses to be controlled under the Building Regulations.

                                                          General

                                                          Use of the document
                                                          B1.x Section 1 deals with fire detection and alarm systems. Section 2 deals with means of escape.

                                                          B1 Section 1

                                                          Fire detection and fire alarm systems

                                                          Introduction

                                                          1.1 Provisions are made in this section for suitable arrangements to be made in dwellinghouses to give early warning in the event of fire.

                                                          General

                                                          1.2 The installation of smoke alarms, or automatic fire detection and alarm systems can significantly increase the level of safety by automatically giving an early warning of fire. The following guidance is appropriate for most dwellinghouses. However, where it is known that the occupants of a proposed dwellinghouse are at a special risk from fire, it may be more appropriate to provide a higher standard of protection, e.g. additional detectors. 1.3 All new dwellinghouses should be provided with a fire detection and fire alarm system in accordance with the relevant recommendations of BS 5839-6:2004 to at least a Grade D Category LD3 standard. 1.4 The smoke and heat alarms should be mains-operated and conform to BS EN 14604: 2005, Smoke alarm devices or BS 5446-2:2003, Fire detection and fire alarm devices for dwellinghouses, Part 2 Specification for heat alarms, respectively. They should have a standby power supply, such as a battery (either rechargeable or non-rechargeable) or More information on power supplies is given in clause 15 of BS 5839-6:2004. Note: BS EN 14604 covers smoke alarms based on ionization chamber smoke detectors and optical (photo-electric) smoke detectors. The different types of detector respond differently to smouldering and fast-flaming fires. Either type of detector is generally suitable. However, the choice of detector type should, if possible, take into account the type of fire that might be expected and the need to avoid false alarms. Optical detectors tend to be less affected by low levels of ‘invisible’ particles, such as fumes from kitchens, that often cause false alarms. Accordingly, they are generally more suitable than ionization chamber detectors for installation in circulation spaces adjacent to kitchens.  

                                                          Large houses

                                                          1.5 A dwellinghouse is regarded as large if it has more than one storey and any of those storeys exceed 200sqm. 1.6 A large dwellinghouse of 2 storeys (excluding basement storeys) should be fitted with a fire detection and fire alarm system of Grade B category LD3 as described in BS 5839-6:2004. 1.7 A large dwellinghouse of 3 or more storeys (excluding basement storeys) should be fitted with a Grade A Category LD2 system as described in BS 5839-6:2004, with detectors sited in accordance with the recommendations of BS 5839-1:2002 for a Category L2 system.

                                                          Material alterations

                                                          1.8 Where new habitable rooms are provided above the ground floor level, or where they are provided at ground floor level and there is no final exit from the new room, a fire detection and fire alarm system should be installed. Smoke alarms should be provided in the circulation spaces of the dwellinghouse in accordance with paragraphs 1.10 to 1.18 to ensure that any occupants of the new rooms are warned of any fire that may impede their escape.

                                                          Sheltered housing
                                                          1.9 The detection equipment in a sheltered housing scheme with a warden or supervisor should have a connection to a central monitoring point (or alarm receiving centre) so that the person in charge is aware that a fire has been detected in one of the dwellinghouses and can identify the dwellinghouse concerned. These provisions are not intended to be applied to the common parts of a sheltered housing development, such as communal lounges, or to sheltered accommodation in the Institutional or Other residential purpose groups (see Approved Document B Volume 2).
                                                          Positioning of smoke and heat alarms
                                                          1.10 Detailed guidance on the design and installation of fire detection and alarm systems in dwellinghouses is given in BS 5839-6:2004. However, the following guidance is appropriate to most common situations. 1.11 Smoke alarms should normally be positioned in the circulation spaces between sleeping spaces and places where fires are most likely to start (e.g. kitchens and living rooms) to pick up smoke in the early stages of a fire. 1.12 There should be at least one smoke alarm on every storey of a dwellinghouse. 1.13 Where the kitchen area is not separated from the stairway or circulation space by a door, there should be a compatible interlinked heat detector or heat alarm in the kitchen, in addition to whatever smoke alarms are needed in the circulation space(s). 1.14 Where more than one alarm is installed they should be linked so that the detection of smoke or heat by one unit operates the alarm signal in all of them. The manufacturers' instructions about the maximum number of units that can be linked should be observed. 1.15 Smoke alarms/detectors should be sited so that: A. There is a smoke alarm in the circulation space within 5m of the door to every habitable room; B. They are ceiling-mounted and at least 300mm from walls and light fittings (unless, in the case of light fittings, there is test evidenceto prove that the proximity of the light fitting will not adversely affect the efficiency of the detector). Units designed for wall-mounting may also be used provided that the units are above the level of doorways opening into the space and they are fixed in accordance with manufacturers’ instructions; and C. The sensor in ceiling-mounted devices is between 25mm and 600mm below the ceiling (25-150mm in the case of heat detectors or heat alarms). Note: This guidance applies to ceilings that are predominantly flat and horizontal. 1.16 It should be possible to reach the smoke alarms to carry out routine maintenance, such as testing and cleaning, easily and safely. For this reason smoke alarms should not be fixed over a stair or any other opening between floors. 1.17 Smoke alarms should not be fixed next to or directly above heaters or air-conditioning outlets. They should not be fixed in bathrooms, showers, cooking areas or garages, or any other place where steam, condensation or fumes could give false alarms. 1.18 Smoke alarms should not be fitted in places that get very hot (such as a boiler room) or very cold (such as an unheated porch). They should not be fixed to surfaces which are normally much warmer or colder than the rest of the space, because the temperature difference might create air currents which move smoke away from the unit.

                                                          Power supplies

                                                          1.19 The power supply for a smoke alarm system should be derived from the dwellinghouse's mains electricity supply. The mains supply to the smoke alarm(s) should comprise a single independent circuit at the dwellinghouse's main distribution board (consumer unit) or a single regularly used local lighting circuit. This has the advantage that the circuit is unlikely to be disconnected for any prolonged period. There should be a means of isolating power to the smoke alarms without isolating the lighting. 1.20 The electrical installation should comply with Approved Document P (Electrical safety). 1.21 Any cable suitable for domestic wiring may be used for the power supply and interconnection to smoke alarm systems. It does not need any particular fire survival properties except in large houses (BS 5839-6:2004 specifies fire resisting cables for Grade A and B systems). Any conductors used for interconnecting alarms (signalling) should be readily distinguishable from those supplying mains power, e.g. by colour coding. Note: Mains-powered smoke alarms may be interconnected using radio-links, provided that this does not reduce the lifetime or duration of any standby power supply below 72 hours. In this case, the smoke alarms may be connected to separate power circuits (see paragraph 1.19) 1.22 Other effective options exist and are described in BS 5839-1:2002 and BS 5839-6:2004. For example, the mains supply may be reduced to extra low voltage in a control unit incorporating a standby trickle-charged battery, before being distributed at that voltage to the alarms.

                                                          Design and installation of systems

                                                          1.23 It is essential that fire detection and fire alarm systems are properly designed, installed and maintained. Where a fire alarm system is installed, an installation and commissioning certificate should be provided. Third party certification schemes for fire protection products and related services are an effective means of providing the fullest possible assurances, offering a level of quality, reliability and safety. 1.24 A requirement for maintenance cannot be made as a condition of passing plans by the Building Control Body. However, the attention of developers and builders is drawn to the importance of providing the occupants with information on the use of the equipment, and on its maintenance (or guidance on suitable maintenance contractors). See paragraph 0.11. Note: BS 5839-1 and BS 5839-6 recommend that occupiers should receive the manufacturers' instructions concerning the operation and maintenance of the alarm system.

                                                          B1 Section 2

                                                          Means of escape

                                                          Introduction

                                                          2.1 The means of escape from a typical one or two storey dwellinghouse is relatively simple to provide. Few provisions are specified in this document beyond ensuring that means are provided for giving early warning in the event of fire (see Section 1) and that suitable means are provided for emergency egress from each storey via windows or doors. With increasing height more complex provisions are needed because emergency egress through upper windows becomes increasingly hazardous. It is then necessary to protect the internal stairway. If there are floors more than 7.5m above ground level, the risk that the stairway will become impassable before occupants of the upper parts of the dwellinghouse have escaped is appreciable, and an alternative route from those parts should be provided. See Diagram 1. Note: Ground level is explained in Appendix C, Diagram C1. 2.2  In providing any kind of fire protection in houses it should be recognised that measures which significantly interfere with the day-to-day convenience of the occupants may be less reliable in the long term.

                                                          Provisions for escape from the ground storey

                                                          2.3 Except for kitchens, all habitable rooms in the ground storey should either:

                                                          • A. Open directly onto a hall leading to the entrance or other suitable exit; or
                                                          • B. Be provided with a window (or door) which complies with paragraph 2.8.
                                                            Note: See also General Provisions.

                                                          Provisions for escape from upper floors not more than 4.5m above ground level

                                                          2.4 Except for kitchens, all habitable rooms in the upper storey(s) of a dwellinghouse served by only one stair should be provided with:

                                                          • A. A window (or external door) which complies with paragraph 2.8; or
                                                          • B. Direct access to a protected stairway (as described in 2.6 (a) or (b)).
                                                          Note: A single window can be accepted to serve two rooms provided both rooms have their own access to the stairs. A communicating door between the rooms should also be provided so that it is possible to gain access to the window without passing through the stair enclosure. Note: See also General Provisions.

                                                          Provisions for escape from upper floors more than 4.5m above ground level

                                                          2.5 The provisions described in 2.6 and 2.7 need not be followed if the dwellinghouse has more than one internal stairway, which afford effective alternative means of escape and are physically separated from each other. Note:The necessary degree of separation is a matter of judgement, eg. stairs may be separated by fire-resisting construction or by a number of rooms.

                                                          Dwellinghouses with one floor more than 4.5m above ground level
                                                          2.6 The dwellinghouse may either have a protected stairway as described in (a) below, or the top floor can be separated and given its own alternative escape route as described in (b).
                                                          • A. The upper storeys (those above ground storey) should be served by a protected stairway (protected at all levels) which should either:
                                                            • i. Extend to a final exit, see Diagram 2(a)
                                                            • ii. Give access to at least two escape routes at ground level, each delivering to final exits and separated from each other by fire-resisting construction and fire doors, see Diagram 2(b); or
                                                          • B. The top storey should be separated from the lower storeys by fire-resisting construction and be provided with an alternative escape route leading to its own final exit. See Diagram 3.
                                                          Notes:See also General Provisions.
                                                          Dwellinghouses with more than one floor over 4.5m above ground level
                                                          2.7 Where a dwellinghouse has two or more storeys with floors more than 4.5m above ground level (typically a dwellinghouse of four or more storeys) then, in addition to meeting the provisions in paragraph 2.6:
                                                          • A. an alternative escape route should be provided from each storey or level situated 7.5m or more above ground level. Where the access to the alternative escape route is via:
                                                            • i. The protected stairway to an upper storey; or
                                                            • ii. A landing within the protected stairway enclosure to an alternative escape route on the same storey; then
                                                            • iii. The protected stairway at or about 7.5m above ground level should be separated from the lower storeys or levels by fire-resisting construction, see Diagram 3; or
                                                          • B. the dwellinghouse should be fitted throughout with a sprinkler system designed and installed in accordance with BS 9251:2005.
                                                          Notes: See also General Provisions. Diagram1- Means of escape form dwellinghouses Diagram1 - Means of escape from dwellinghouses Diagram 2 - Alternative arrangements for final exits Diagram 2 - Alternative arrangements for final exits Diagram 3 - Fire separation in houses with more than one floor over 4.5m above ground level Diagram 3 - Fire separation in houses with more than one floor over 4.5m above ground level  

                                                          General provisions

                                                          Emergency egress windows and external doors

                                                          2.8 Any window provided for emergency egress purposes and any external door provided for escape should comply with the following conditions:

                                                          • A. the window should have an unobstructed openable area that is at least 0.33m2 and at least 450mm high and 450mm wide (the route through the window may be at an angle rather than straight through). The bottom of the openable area should be not more than 1100mm above the floor; and
                                                          • B. the window or door should enable the person escaping to reach a place free from danger from fire. This is a matter for judgement in each case, but, in general, a courtyard or back garden from which there is no exit other than through other buildings would have to be at least as deep as the dwellinghouse is high to be acceptable, see Diagram 4.
                                                          Note 1: Approved Document K Protection from falling, collision and impact specifies a minimum guarding height of 800mm, except in the case of a window in a roof where the bottom of the opening may be 600mm above the floor. Note 2: Locks (with or without removable keys) and stays may be fitted to egress windows, subject to the stay being fitted with a release catch, which may be child resistant. Note 3: Windows should be designed such that they will remain in the open position without needing to be held by a person making their escape. 4 - Ground or basement storey exit into an enclosed space Diagram 4 - Ground or basement storey exit into an enclosed space

                                                          Inner Rooms

                                                          2.9 A room whose only escape route is through another room is termed an inner room and is at risk if a fire starts in that other room (access room). This situation may arise with open-plan layouts and galleries. Such an arrangement is only acceptable where the inner room is:

                                                          1. a kitchen;
                                                          2. a laundry or utility room;
                                                          3. a dressing room;
                                                          4. a bathroom, WC, or shower room;
                                                          5. any other room on a floor, not more than 5m above ground level, provided with an emergency egress window which complies with paragraph 2.8; or
                                                          6. a gallery which complies with paragraph 12.
                                                          Note: A room accessed only via an inner room (an inner-inner room) may be acceptable if it complies with the above, not more than one door separates the room from an interlinked smoke alarm and none of the access rooms is a kitchen.  

                                                          Balconies and flat roofs

                                                          2.10 A flat roof forming part of a means of escape should comply with the following provisions:

                                                          1. the roof should be part of the same building from which escape is being made;
                                                          2. the route across the roof should lead to a storey exit or external escape route; and
                                                          3. the part of the roof forming the escape route and its supporting structure, together with any opening within 3m of the escape route, should provide 30 minutes fire resistance (see Appendix A, Table A1).
                                                          2.11 Where a balcony or flat roof is provided for escape purposes guarding may be needed, in which case it should meet the provisions in Approved Document K Protection from falling, collision and impact.

                                                          Galleries

                                                          2.12 A gallery should be provided with an alternative exit or, where the gallery floor is not more than 4.5m above ground level, an emergency egress window which complies with paragraph 2.8. Alternatively, where the gallery floor is not provided with an alternative exit or escape window, it should comply with the following;

                                                          1. the gallery should overlook at least 50% of the room below (see Diagram 5);
                                                          2. the distance between the foot of the access stair to the gallery and the door to the room containing the gallery should not exceed 3m;
                                                          3. the distance from the head of the access stair to any point on the gallery should not exceed 7.5m; and
                                                          4. any cooking facilities within a room containing a gallery should either:
                                                            • be enclosed with fire-resisting construction; or
                                                            • be remote from the stair to the gallery and positioned such that they do not prejudice the escape from the gallery
                                                          5 - Gallery floors with no alternative exit Diagram 5 - Gallery floors with no alternative exit

                                                          Basements

                                                          2.13 Because of the risk that a single stairway may be blocked by smoke from a fire in the basement or ground storey, if the basement storey contains any habitable room, the dwellinghouse should be provided with either:
                                                          • an external door or window suitable for egress from the basement (see paragraph 2.8); or
                                                          • a protected stairway leading from the basement to a final exit

                                                          Cavity Barriers

                                                          2.14 Cavity barriers should be provided above the enclosures to a protected stairway in a dwellinghouse with a floor more than 4.5m above ground level (see Diagram 6). Diagram 6 - Alternative cavity barrier arrangements in roof space over protected stairway in a house with a floor more than 4.5m above ground level Diagram 6 - Alternative cavity barrier arrangements in roof space over protected stairway in a house with a floor more than 4.5m above ground level

                                                          External Escape stairs

                                                          2.15 Where an external escape stair is provided, it should meet the following provisions:

                                                          1. All doors giving access to the stair should be fire-resisting, except that a fire-resisting door is not required at the head of any stair leading downwards where there is only one exit from the building onto the top
                                                          2. Any part of the external envelope of the building within 1800mm of (and 9m vertically below) the flights and landings of an external escape stair should be of fire-resisting construction, except that the 1800mm dimension may be reduced to 1100mm above the top level of the stair if it is not a stair up from a basement to ground level (see Diagram 7).
                                                          3. There is protection by fire-resisting construction for any part of the building (including any doors) within 1800mm of the escape route from the stair to a place of safety, unless there is a choice of routes from the foot of the stair that would enable the people escaping to avoid exposure to the effects of the fire in the adjoining
                                                          4. Any stair more than 6m in vertical extent is protected from the effects of adverse weather (This should not be taken to imply a full enclosure. Much will depend on the location of the stair and the degree of protection given to the stair by the building itself).
                                                          5. Glazing in areas of fire-resisting construction mentioned above should also be fire-resisting (integrity but not insulation) and fixed shut
                                                          Diagram 7 - Fire resistance of areas adjacent to external stairs Diagram 7 - Fire resistance of areas adjacent to external stairs

                                                          Air circulation systems in houses with a floor more than 4.5m above ground level

                                                          2.16 Air circulation systems which circulate air within an individual dwellinghouse with a floor more than 4.5m above ground level should meet the guidance given in paragraph 2.17. Where ventilation ducts pass through compartment walls into another building then the guidance given in Approved Document B Volume 2 should be2.17 With these types of systems, the following precautions are needed to avoid the possibility of the system allowing smoke or fire to spread into a protected stairway:

                                                          1. Transfer grilles should not be fitted in any wall, door, floor or ceiling enclosing a protected
                                                          2. Any duct passing through the enclosure to a protected stairway or entrance hall should be of rigid steel construction and all joints between the ductwork and the enclosure should be fire-stopped.
                                                          3. Ventilation ducts supplying or extracting air directly to or from a protected stairway, should not serve other areas as
                                                          4. Any system of mechanical ventilation which recirculates air and which serves both the stairway and other areas should be designed to shut down on the detection of smoke within the
                                                          5. A room thermostat for a ducted warm air heating system should be mounted in the living room, at a height between 1370mm and 1830mm, and its maximum setting should not exceed 27ºC.

                                                          Passenger Lifts

                                                          2.18 Where a passenger lift is provided in the dwellinghouse and it serves any floor more than 5m above ground level, it should either be located in the enclosure to the protected stairway (see paragraph 2.6) or be contained in a fire- resisting lift shaft.

                                                          Work on existing houses

                                                          Replacement windows

                                                          2.19 Regulation 4(1) requires that all "building work", as defined by Regulation 3, complies with the applicable requirements of Schedule 1 to the Building Regulations. The definition of building work in Regulation 3(1) includes the provision or extension of a "controlled service or fitting" in or in connection with a building. The definition of controlled service or fitting is given in Regulation 2(1), and includes a replacement window. Where windows are to be replaced (but not where they are to be repaired only, as repair work to windows does not fall within the definition of building work) the replacement work should comply with the requirements of Parts L and N of Schedule 1. In addition, the building should not have a lesser level of compliance, after the work has been completed, with other applicable Parts of Schedule 1. For the purposes of Part B1, where a window is located such that, in a new dwellinghouse, an escape window would be necessary and the window is of sufficient size that it could be used for the purposes of escape then: A. the replacement window opening should be sized to provide at least the same potential for escape as the window it replaces; or B. where the original window is larger than necessary for the purposes of escape, the window opening could be reduced down to the minimum specified in paragraph 2.8. Note: Part B3 makes provisions for cavity barriers around window openings in some forms of construction. Where windows are replaced it may be necessary to consider if adequate protection is maintained.

                                                          Material alterations 2.20Paragraph 0.20 sets out the requirements relating to material alterations. What constitutes reasonable provision where undertaking material alterations would depend on the circumstances in the particular case and would need to take account of historic value (see paragraph 0.29). Possible ways of satisfying the requirements include: a. Smoke alarms Where new habitable rooms are provided then smoke alarms should be provided in accordance with paragraph 1.8. b. Loft conversions Where a new storey is to be added by converting an existing roof space, the provisions for escape need to be considered throughout the full extent of the escape route. For example, a loft conversion to a two-storey house will result in the need to protect the stairway (by providing fire-resisting doors and partitions) where previously no protection may have existed (see paragraph 2.6a). Note: If it is considered undesirable to replace existing doors (e.g. if they are of historical or architectural merit) it may be possible to retain the doors or upgrade them to an acceptable standard. Note: Where an 'open-plan' arrangement exists at ground level it may be necessary to provide a new partition to enclose the escape route (see Diagram 2). Alternatively, it may be possible to provide sprinkler protection to the open-plan area, in conjunction with a fire-resisting partition and door (E20), in order to separate the ground floor from the upper storeys. This door should be so arranged to allow the occupants of the loft room to access an escape window at first floor level (in accordance with paragraph 2.8) in the event of a fire in the open-plan area. Cooking facilities should be separated from the open-plan area with fire-resisting construction.

                                                          Material alterations

                                                          2.20 Paragraph 0.20 sets out the requirements relating to material alterations. What constitutes reasonable provision where undertaking material alterations would depend on the circumstances in the particular case and would need to take account of historic value (see paragraph 0.29). Possible ways of satisfying the requirements include: a.    Smoke alarms Where new habitable rooms are provided then smoke alarms should be provided in accordance with paragraph 1.8. b.    Loft conversions Where a new storey is to be added by converting an existing roof space, the provisions for escape need to be considered throughout the full extent of the escape route. For example, a loft conversion to a two-storey house will result in the need to protect the stairway (by providing fire-resisting doors and partitions) where previously no protection may have existed (see paragraph 2.6a). Note: If it is considered undesirable to replace existing doors (e.g. if they are of historical or architectural merit) it may be possible to retain the doors or upgrade them to an acceptable standard. Note: Where an ‘open-plan’ arrangement exists at ground level it may be necessary to provide a new partition to enclose the escape route (see Diagram 2). Alternatively, it may be possible to provide sprinkler protection to the open-plan area, in conjunction with a fire-resisting partition and door (E20), in order to separate the ground floor from the upper storeys. This door should be so arranged to allow the occupants of the loft room to access an escape window at first floor level (in accordance with paragraph 2.8) in the event of a fire in the open-plan area. Cooking facilities should be separated from the open-plan area with fire-resisting construction.  

                                                          • Diagram1- Means of escape form dwellinghouses Diagram1 - Means of escape form dwellinghouses
                                                          • Diagram 2 - Alternative arrangements for final exits Diagram 2 - Alternative arrangements for final exits
                                                          • Diagram 3 - Fire separation in houses with more than one floor over 4.5m above ground level Diagram 3 - Fire separation in houses with more than one floor over 4.5m above ground level
                                                          • Diagram 4 - Ground or basement storey exit into an enclosed space Diagram 4 - Ground or basement storey exit into an enclosed space.
                                                          • Diagram 5 - Gallery floors with no alternative exit
                                                          • Diagram 6 - Alternative cavity barrier arrangements in roof space over protected stairway in a house with a floor more than 4.5m above ground level Diagram 6 - Alternative cavity barrier arrangements in roof space over protected stairway in a house with a floor more than 4.5m above ground level
                                                          • Diagram 7 - Fire resistance of areas adjacent to external stairs Diagram 7 - Fire resistance of areas adjacent to external stairs
                                                          • Diagram 8 - Lighting diffuser in relation to ceiling Diagram 8 - Lighting diffuser in relation to ceiling
                                                          • Diagram 9 - Layout restrictions on Class 3 plastice rooflights, TP(b) rooflights and TP(b) lighting diffusers Diagram 9 - Layout restrictions on Class 3 plastice rooflights, TP(b) rooflights and TP(b) lighting diffusers
                                                          • Diagram 10 - Separation between garage and dwellinghouse Diagram 10 - Separation between garage and dwellinghouse
                                                          • Diagram 11 - Junction of compartment wall with roof Diagram 11 - Junction of compartment wall with roof
                                                          • Diagram 12 - Interrupting concealed spaces (cavities) Diagram 12 - Interrupting concealed spaces (cavities)
                                                          • Diagram 13 - Cavity walls excluded from provisions for cavity barriers Diagram 13 - Cavity walls excluded from provisions for cavity barriers
                                                          • Diagram 14 - Pipes penetrating structure Diagram 14 - Pipes penetrating structure
                                                          • Diagram 15 - Enclosure for drainage or water supply pipes Diagram 15 - Enclosure for drainage or water supply pipes
                                                          • Diagram 16 - Fules penetrating compartment walls or floors Diagram 16 - Fules penetrating compartment walls or floors
                                                          • Diagram 17 - Relevant boundary Diagram 17 - Relevant boundary
                                                          • Diagram 18 - Notional boundary Diagram 18 - Notional boundary
                                                          • Diagram 19 - Status of combustible surface material as unprotected area Diagram 19 - Status of combustible surface material as unprotected area
                                                          • Diagram 20 - Unprotected areas which may be disregarded in assessing the separation distances from the boundry Diagram 20 - Unprotected areas which may be disregarded in assessing the separation distances from the boundry
                                                          • Diagram 21 - The effect of a conopy on separation distance Diagram 21 - The effect of a conopy on separation distance
                                                          • Diagram 22 - Permitted unprotected areas for Method 1 Diagram 22 - Permitted unprotected areas for Method 1
                                                          • Diagram 23 - Limitations on spacing and size of plastic rooflights having a Class 3 (National class) or Class D-s3, d2 (European class) or TP(b) lower surface Diagram 23 - Limitations on spacing and size of plastic rooflights having a Class 3 (National class) or Class D-s3, d2 (European class) or TP(b) lower surface
                                                          • Diagram 24 - Turning facilities Diagram 24 - Turning Facilities
                                                          • Table 1 - Classification of linings Table 1 - Classification of linings
                                                          • Table 3 - Maximum nominal internal diameter of pipes passing through a fire separating element Table 3 - Maximum nominal internal diameter of pipes passing through a fire separating element
                                                          • Table 3 - Maximum nominal internal diameter of pipes passing through a fire separating element Table 3 - Maximum nominal internal diameter of pipes passing through a fire separating element
                                                          • Table 4 - Permitted unprotected areas for Method 2 Table 4 - Permitted unprotected areas for Method 2
                                                          • Table 5 - Limitations on rood coverings Table 5 - Limitations on rood coverings
                                                          • Table 6- Class 3 (National class) or Class D-s3, d2 (eurpean class) plstic rooflights - limitations on use and boundary distance Table 6- Class 3 (National class) or Class D-s3, d2 (eurpean class) plstic rooflights - limitations on use and boundary distance
                                                          • Table 7 - TP (a) and TP (b) plastic rooflights- limitations on use and boundary distance Table 7 - TP (a) and TP (b) plastic rooflights- limitations on use and boundary distance
                                                          • Table A8 - Typical performance ratings of some generic materails and products Table A8 - Typical performance ratings of some generic materails and products
                                                          • Table A1 - Specific provisions of test for fire resistance of elements of structure etc Table A1 - Specific provisions of test for fire resistance of elements of structure etc
                                                          • Table A1 continued Table A1 continued
                                                          • Table A2 - Minimum periods of fire resistance for dwellinghouses Table A2 - Minimum periods of fire resistance for dwellinghouses
                                                          • Table A3 - Limitations on fire - protecting suspended ceilings (see Table A1, Note 4) Table A3 - Limitations on fire - protecting suspended ceilings (see Table A1, Note 4)
                                                          • Table A4 - Limitations on the use of uninsulated glazed elements on escape routes Table A4 - Limitations on the use of uninsulated glazed elements on escape routes
                                                          • Table A5 - Notional designations of roof coverings Table A5 - Notional designations of roof coverings
                                                          • Table A6 - Use and definitions of non-combustible materials Table A6 - Use and definitions of non-combustible materials
                                                          • Table A7 - Use and definitions of materails of limited combustibillty Table A7 - Use and definitions of materails of limited combustibillty
                                                          • Table A8 - Typical performance ratings of some generic materails and products Table A8 - Typical performance ratings of some generic materails and products
                                                          • Table B1 Provision for fire doors Table B1 Provision for fire doors
                                                          • Table  C1 - Height of top storey in building Table C1 - Height of top storey in building
                                                          • Table D1 - Classification of Purpose Groups Table D1 - Classification of Purpose Groups