Fire Precautions in Dwellings
The Design of Escape (Egress) Windows
Where window openings are likely to be used for means of escape purposes the following guidance must be referred to:
- The window must have an unobstructed openable window area that is at least 0.33m2 with at least the width or height dimension being a minimum of 450mm. Side hung opening lights are recommended. Care must be taken when considering the design (particularly with UPVC windows and their various hinge designs) to ensure the necessary openable area required is provided.
- The bottom of the openable area (windowsill level) must be not more than 1100mm, and not less than 800mm above floor level. Windows are suitable for means of escape where the drop from the window to ground level is one storey only (not exceeding 4.5m from first floor level to outside ground level).
Note: the ground below the windows must be flat and free from hazards (low walls, railings etc). Where security is provided on windows, means of opening must be readily available within the room. Where primary access to a sleeping room is through a high-risk room (i.e. communal, kitchen or living room) an alternative suitable means of escape must be provided via a door or escape window directly to the outside.
Escape Route Separation
Where specified in this guidance the means of escape through an HMO should be capable of offering 30-minutes fire and smoke resistance. This is to allow the occupants of the property sufficient time to escape to a place of safety.
In certain high-risk circumstances there may be a requirement to provide 60-minutes fire and smoke resistance. For example:
- Walls, ceilings, and doors separating commercial uses from residential parts.
- Walls, ceilings, and doors separating areas of high fire risk, e.g., commercial kitchens, large boiler rooms, and large stores.
- Separating walls between buildings.
- Basement or cellar areas that are not fitted with automatic fire detection.
When constructing and installing new partition walls compliance with current Building Regulations must be achieved as a minimum standard. In certain circumstances there may be a requirement to upgrade existing ceilings and partition walls to achieve adequate fire and smoke resistance.
Existing Partitions - 30-minutes protection:
The condition of the lath and plaster partition must be examined in detail. Retention of the partition surfaces must only be considered if in good condition and there is no loose or failing plaster.
In the event of minor damage or inconclusive investigation of the partition construction, the partition must be upgraded on the risk side (room side) by replacing the lath and plaster or by over boarding it with 12.5mm gypsum wallboard or fire line board fixed with galvanized clout/plasterboard nails. These should have sufficient length to penetrate the lath and plaster and provide a firm fixing in the timber framework. The partition should be finished by skimming and skimming with plaster.
Partition walls not of traditional lath and plaster construction but of a timber frame and wall board construction must be in good repair and of the following specification to achieve 30-minutes fire and smoke resistance:
- The stud work framing must be formed of timbers of minimum dimensions 38mm x 75mm x 450mm (centres).
- The stud work framing must be faced on both sides with a minimum of 9.5mm gypsum wallboard with Hessian scrim to all joints and a 5mm (minimum) plaster coat finish.
Existing Partitions - 60-minutes protection:
The following methods can be used to upgrade an existing (lath and plaster) partition made up of 75mm x 50mm timber studs which is either load bearing or non-loadbearing. The studs at maximum 600mm centres with no infill to provide a partition with 60-minute fire resistance, which upgraded.
Partitions can be upgraded in one of two ways:
- By the provision of an additional board to the existing facing on both sides:
- 9mm Supalux fixed, on each side of the partition, using 63mm nails or screws at 300mm centres.
- 12mm New Tacfire fixed, on each side of the partition, using screws at 300mm centres. The length of the screws should be such that they penetrate 38mm into the stud.
- By the provision of a cavity infill:
- In this case it must be a non-load-bearing stud partition made up of minimum 89mm x 38mm studs at 600mm centres with no infill and covered with 12.5mm plasterboard.
- Take off one face of the existing partition. Fill the cavity between the studs with 90mm Rockwool Timberbatts of density 23Kg/m3. Provide 12.5mm Gypsum Wallboard fixed at 150mm centres with 38mm galvanised nails. Joints must be taped and filled or surface skimmed.
- Alternatively, if the timber studs are minimum of 100mm x 38mm at 600mm centres and covered with 12.5mm plasterboard the cavity between the studs can be filled with 100mm Rockwool RW2 slabs.
Any variations or alternatives to the above specifications must be agreed with your Local Authority prior to the works being carried out.
All walls and ceilings in the 30- and 60-minute protected routes are to be of Class 0 surface spread of flame as in accordance with Part B of the Building Regulations. Normal paint and paper are adequate but heavy flock-type paper or timber claddings will not comply.
Additional Escape Route Separation
1. Electricity or Gas meter on escape route
Provide 30-minute fire resisting enclosure to the electric and gas meter. Enclosure to consist of 100mm x 50mm softwood framing faced with 12.5mm plasterboard both sides or alternatively 6mm fire protective board (e.g., Supalux) to the inner side of the framework, scrim joints and apply minimum 3mm plaster skim to outer surface. Provide 30-minute fire resisting door. Where a fire door is to be cut down to fit a smaller door opening, then solid core -minutes fire resistant door blanks only are to be used. Hardwood lippings are to be glued and screwed to leaf edges once the door blank has been cut down to the required size. Ensure points where pipes or cables penetrate the cupboard are tightly sealed with a non-combustible compound capable of maintaining the 30-minutes fire resistant integrity of the cupboard structure (e.g., intumescent foam etc).
Lead pipes are unsatisfactory, and the gas supply pipes should be of high melting point metal. The cupboard to the gas meter should be provided with ventilation grills at high and low levels, these must provide 30-minutes fire protection. The gas provider should be consulted to ensure they are satisfied with the arrangements, as they will require access to read meters.
2. Loft Hatch
Loft hatches must provide the 30-minutes fire resistance to the ceiling structure along the means of escape for the property.
Remove the existing loft hatch. Provide and fix suitable lining complete with minimum 25mm deep stops, both to be glued and screwed to loft hatch frame. Provide and fit 30-minutes fire resistant loft hatch door to comprise solid core 30- minutes fire door blank cut down to appropriate size, with hardwood lippings glued and screwed to each leaf edge. Provide and fit 10mm intumescent and smoke seals to be pinned into rebates on each leaf edge of the loft hatch door or alternatively into the loft hatch frame. The whole door to fit into the existing frame with no more than a 4mm gap at any point between the hatch door and the frame. 2-barrel bolts are to be provided and fitted on opposite sides of the exposed face to keep the hatch in a closed position under pressure when not in use.
3. Under stairs cupboard
The soffit and spandrel partition to the staircase is to be made to achieve 30-minutes fire resistance. Apply to the existing soffit and spandrel 12.5mm plasterboard with 3mm skim coat, or 6mm minimum fire protective board (e.g., Supalux) with all joints filled with fire resisting compound. The cupboard below the stairs at ground floor level, in addition to the above, is to have all combustible materials removed.
Fit a new 30-minutes fire resisting door and frame. The door is to be kept locked shut. Apply notice to door reading "TO BE KEPT LOCKED SHUT", to comply with The Health and Safety (Safety Signs and Symbols) Regulations 1996.
4. Lobby Protection
A lobby area is a fire resisting structure located between the protected means of escape and the risk rooms (e.g., bedrooms, living rooms, kitchens). A lobby provides additional protection in the event of a fire by providing what is sometimes referred to as double-door protection that is, for example, to enter a bed-sit room that has lobby protection it is necessary to go through two fire doors. More than one risk room is often accessed via a single lobby.
Small, well-constructed lobbies are more effective at preventing the spread of smoke into the means of escape than large lobbies as they generally leak less air. This helps create a back pressure that effectively forms a barrier between the room that is on fire and the means of escape or vice versa.
5. Secondary Means of Escape
A secondary means of escape refers to a second or alternative means of escape from the building, or area of a building, other than the usual route used to enter and exit the building.
Typically, in the larger, higher-risk HMOs a secondary means of escape will comprise of an external staircase securely attached to the rear or side of the building.
In older buildings a secondary means of escape is often provided by means of a "kick-through" or door that leads into protected means of escape in an adjacent building. Such escape facilities are undesirable and should be designed out wherever possible.
The use of egress windows as a secondary means of escape is only acceptable from basement, ground or first floor levels.