HOW TO FIRE-RESISTING CONSTRUCTION

FIRE-RESISTING CONSTRUCTION

 A fully fire resistant building is fully protected against any fire which occur in is contents.

Causes of Fire: The causes of various types of fire hazards are described in details:

• Electrical hazards: Damaged wiring, Damaged plugs, Damp or wet wires, Overloaded

motors, Broken switches, outlets or sockets, Problems with lighting fixtures, Faulty

heating elements, Overloaded circuits, Liquids near computers, Computers without surge

protectors.

• Housekeeping hazards: Piles of scrap, waste materials, and trash; Sawdust, metal or

plastic powder that can form an explosive mixture with air; Obstructed aisles, Blocked

emergency exits, Material covering up fire extinguishers, exit signs, and alarms; Blocked

sprinkler heads.

• Friction hazards: Hot bearings, Misaligned or broken machine parts, choking or

jamming materials, Poor adjustment of moving parts, Inadequate lubrication.

• process or operation-related hazards: Cutting and welding operations, which use

open flames and produce sparks; Molten metal, which can ignite combustibles or fall into

cracks and start a fire that might not erupt until after the work is done; Processes that heat

materials to high temperatures; Drying operations where materials in dryers can overheat;

Grinding operations that produce sparks and dust; Processes in which flammable vapors

are released

• Storage hazards: Materials stacked too high blocking sprinkler heads (need 18-inches

clearance from head); Flammable or combustible materials stored too close to heat

sources; Flammable materials not stored in special containers and cabinets Inadequate

ventilation in storage areas; Materials that might react with one another stored together;

Materials stored in damaged containers; Materials stored in unlabeled containers;

Containers not tightly sealed

• Smoking hazards: Ignoring "No Smoking" signs; Smoking around flammable or

combustible materials; Throwing matches and cigarettes or cigars on tables or

workbenches; Tossing butts on the floor or grass without properly extinguishing them in

an ashtray or ash can; Tossing lighted butts or matches out windows or doors; Smoking in

bed; Leaving a cigarette/cigar unattended; Smoking in areas where there is an

accumulation of sawdust, plastic or metal powders that may become explosive.

Fire Load: It is the amount of heat liberated in KJ/m2 of floor area of any component by

the combustion of the content of and any combustible part of building itself. The

classification of fire load as per BIS: 1641-1960 are as follows:

1. Low fire load: not exceeding 1.15× 106 KJ/m2

2. Moderate fire Load: 1.15× 106 KJ/m2 to 2.30× 106

3. High fire Load: 2.23× 106 KJ/m2 to 4.60× 106

Limiting Fire Load:

1. Providing fire Fighting Equipment

2. Using fire resistant materials for construction

3. Providing suitable means of escape

4. Protection of openings

Characteristics of fire resisting materials:

• The composition of the material should be such that it does not become disintegrated

under the effect of great heat.

• The expansion of the material due to heat should not be such that it leads to instability

of the structure.

• The contraction of the material due to the sudden cooling with water after it has not

been heated to a high temperature should not be rapid.

Fire resisting properties of common building materials:

Fire resisting properties of common building materials such as stone, brick, glass, steel and

concrete are described below:

a. Stone: stone is a bad conductor of heat and it is also a non-combustible material;

however, it suffers appreciable under effect of fire. Moreover, the stone is also liable to

disintegrate in to small pieces when heated and suddenly cooled.

b. Brick: Bricks are not seriously affected until very high temperatures around 1200 oC to

1300 oC are reached. This is due to the fact that a brick is poor conductor of heat.

c. Cast-iron: The material files in to pieces when heated and suddenly cooled. Therefore,

when this material in construction. It is covered either by brickwork of one- brick

thickness or any other fire resisting material such as construction.

d. Timber: Generally, the structural elements made of timber ignite and get rapidly

destroyed in case of fire. To increase the timber more fire resisting, the surfaces of

timbers are coated with chemicals such as ammonium phosphate and sulphate, borax and

boric acid, zinc chloride.

e. Glass: The materials are poor conductor of heat and its expansion due to heat is small.

The cracks are formed in this material when heated and suddenly cooled.

f. Wrought- iron: This material is rarely used as structural as present. It behaves more or

less in the same way mild steel.

g. Aluminium: Very good conductor of heat, it possess poor fire resisting properties.

h. Asbestos Cement: this is non-combustible building material with low coefficient of

expansion. It therefore possesses high fire resisting property than other material.

Fire Protection System:

 The system which protects a large area from fire by using

components such as pipes, pump sets, control panel, sprinklers or nozzles etc, is known as

fire protection system.

1. Automatic sprinkler system: Most reliable automatic means of fire fighting. It involves

automatic sprinklers attached to a piping system containing water under pressure and

connected to a water supply so that water is discharged immediately sprinkler opened by

fire.

2. Carbon dioxide system: It extinguishes fire by diluting flammable mixture of air and

flammable gas or vapour to proportions below their flammable limits.

3. Dry Chemical system: This system includes a supply of dry chemical, an excellent gas

such as compressed nitrogen detection devices, release mechanism, fixed piping and

nozzles for discharging the dry chemical into hazard area.

4. Foam System: In this system, the mechanical foam is formed by passing foam producing

liquid and water through adequate device. The foam is as aggregate of air filled bubbles.

It is lighter than flammable liquids and oils. The principal components of this system

include proportioning apparatus, concentrated storage tank, water supply, foam maker or

spray foam-heads, heat detecting devices, automatic and manual actuation devices and an

alarm system.

5. Holon System: This indicates a specific family of chemicals which are produced by

replacing one or more hydrogen atoms with halogen atoms. This is contained in cylinders

under pressure in liquid state and it is released through nozzles on piping distribution

arrangement. An actuator is provided a cylinder control value and it is operated either by

electric or pneumatic signal when fire occurs.

6. Hydrant system: in this system, the hydrants are located at suitable points and they can

be operated at suitable points and they can be operated manually or automatically.

7. Water Spray System: The water spray system used for fire extinguish depends upon the

type of spray and can be sprayed in two categories:

• Multi-fire system: water is sprayed in high velocities

• Protective System: Fine water spray of low discharge velocity

Various types of Fire-resisting construction:

The type and age of construction are crucial factors to consider when assessing the adequacy

of existing escape routes. To ensure the safety of people it may be necessary to protect escape

routes from fire. In older premises it is possible that type of construction and materials used

may not perform to current fire standards and refurbishments may have led to:

• Cavities and voids being created, allowing the potential for the unseen spread of fire.

• Doors and hardware being worn by age and movement being less likely to limit the

spread of fire and smoke.

• Damaged or insufficient cavity barriers in modular building construction (e.g.

CLASP or SCOLA type construction).

• Breaches in fire compartment walls, floors and ceilings created by the installation of

new services, (e.g. computer services).

Where an escape route requires the provision of fire resisting construction (e.g. dead end

corridors or protected stairways) the following should be ensured:

• Doors (including access hatches to cupboards, ducts and vertical shafts linking

floors), walls, floors and ceilings protecting escape routes should be capable of

resisting the passage of flame and smoke for long enough for people to escape from

the building (normally 30 min).

• Where false ceilings are provided, fire resistance should extend up to the floor slab

above (for means of escape purposes 30min fire resistance is required).

• Cavity barriers, fire stopping and dampers in ducts are appropriately installed as

required.

General

The materials from which your premises are constructed may determine the speed with

which a fire may spread, affecting the escape routes that people will use. A fire starting in a

building constructed mainly from readily combustible material will spread faster than one

where modern fire-resisting construction materials have been used. Where non- combustible

materials are used and the internal partitions are made from fire-resisting materials, the fire

will be contained for a longer period, allowing more time for the occupants to escape.

Because of the requirements of the Building Regulations you will probably already have

some walls and floors that are fire-resisting and limitations on the surface finishes to certain

walls and ceilings.

You will need to consider whether the standard of fire resistance and surface finishing in the

escape routes is satisfactory, has been affected by wear and tear or alterations and whether

any improvements are necessary.

The following paragraphs give basic information on how fire-resisting construction can

provide up to 30 minutes protection to escape routes. This is the standard recommended for

most situations. If you are still unsure of the level of fire-resistance that is necessary after

reading this information, you should consult a fire safety expert.

Fire resisting construction

The fire resistance of a wall or floor is dependent on the quality of construction and

materials used. Common examples of types of construction that provide 30-minute fire

resistance to escape routes if constructed to the above standards are:

• Internal framed construction wall, non-load bearing, consisting of 72mm x 37mm

timber studs at 600mm centres and faced with 12.5mm of plasterboard with all joints

taped and filled.

• Internal framed construction, non load- bearing, consisting of channel section steel

studs at 600mm centres faced with 12.5mm of plasterboard with all joints taped and

filled;

• Masonry cavity wall consisting of solid bricks of clay, brick earth, shale, concrete or

calcium silicate, with a minimum thickness of 90mm on each leaf.

                                               Figure 1: Fire-resisting construction

There are other methods and products available that will achieve the required standard of

fire resistance and may be more appropriate for the existing construction in your premises.

If there is any doubt about how your building is constructed, then ask for further advice

from a competent person.

Fire-resisting floors

The fire resistance of floors will depend on the existing floor construction as well as the type

of ceiling finish beneath. If you need to upgrade the fire resistance of your floor it may not

be desirable to apply additional fire resistance to the underside of an existing ornate ceiling.

In older buildings there may be a requirement to provide fire resistance between beams and

joists.

A typical example of a 30-minute fire-resisting timber floor is tongue and groove softwood

of not less than 15mm finished thickness on 37mm timber joists, with a ceiling below of one

layer of plasterboard to a thickness of 12.5mm with joints taped and filled and backed by

supporting timber.

There are other, equally valid, methods and products available for upgrading floors. If you

are in any doubt you should ask the advice of a competent person and ensure that the

product is installed in accordance with instructions from the manufacturer or supplier.

Fire resisting glazing

The most common type of fire-resisting glazing is 6mm Georgian wired glazing, which is

easily identifiable. Clear fire-resisting glazing is available and can quickly be identified by a

mark etched into the glass, usually in the corner of the glazed panel, to confirm its fireresisting

standard.

Although this is not compulsory, the marking of glass is supported by the Glass and Glazing

Federation, you should check whether the glazing would be marked accordingly before

purchase.

The glazing should have been installed in accordance with the manufacturer’s instructions

and to the appropriate standard, to ensure that its fire-resisting properties are maintained.

The performance of glazed systems in terms of fire resistance and external fire exposure

should, wherever possible, be confirmed by test evidence. Alternatively, where there is a

lack of test information, ask for an assessment of the proposed construction from suitably

qualified people.

Fire separation of voids

A common problem encountered with fire separation is fire-resisting partitions, which do

not extend above false ceilings to true ceiling height. This may result in unseen fire spread

and a loss of vital protection to the escape routes. It is important therefore to carefully check

all such partitions have been installed correctly.

CLASP and SCOLA type construction

CLASP (Consortium of Local Authorities Special Programme) and SCOLA (Second

Consortium of Local Authorities) are total or systematic methods of construction that were

developed to provide consistent building quality, while reducing the need for traditional

skilled labour. They consist of a metal frame upon which structural panels are fixed. This

results in hidden voids through which fire may spread.

It is important that cavity barriers that restrict the spread of fire are installed appropriately,

especially to walls and floors that need to be fire resisting. If you are in any doubt as to

whether any remedial work will be required, then ask for advice from a competent person.

Breaching fire separation

To ensure effective protection against fire, walls and floors providing fire separation must

form a complete barrier, with an equivalent level of fire resistance provided to any openings

such as doors, ventilation ducts, pipe passages or refuse chutes.

The passing of services such as heating pipes or electrical cables through fire-resisting

partitions leaves gaps through which fire and smoke may spread. This should be rectified by

suitable fire stopping and there are many proprietary products available to suit particular

types of construction. Competent contractors should install such products.

Décor and surface finishes of walls, ceilings and escape routes

The materials used to line walls and ceilings can contribute significantly to the spread of

flame across their surface. Most materials that are used as surface linings will fall into one

of three classes of surface spread of flame. The following are common examples of

acceptable materials for various situations:

Class 0: Materials suitable for circulation spaces and escape routes

• Such materials include brickwork, block work, concrete, ceramic tiles, plaster

finishes (including rendering on wood or metal lathes), wood-wool cement slabs and

mineral fibre tiles or sheets with cement or resin binding.

Note: Additional finishes to these surfaces may be detrimental to the fire performance of the

surface and if there is any doubt about this then consult the manufacturer of the finish.

Class 1: Materials suitable for use in all rooms but not on escape routes

• Such materials include all the Class 0 materials referred to above. Additionally,

timber, hardboard, block-board, particle board, heavy flock wallpapers and

thermosetting plastics will be suitable if flame-retardant treated to achieve a Class 1

standard.

Class 3: Materials suitable for use in rooms of less than 30m2

• Such materials include all those referred to in Class 1, including those that have not

been flame-retardant treated and certain dense timber or plywood and standard glassreinforced

polyesters.

Strong room construction:

This type of construction is adopted to protect important documents, wealth, currency notes

from fire and thieves. Followings are important features of a strong room construction.

1. The walls, floors and ceilings of strong room are constructed with minimum thickness of

30 mm.

2. Grills are to be placed in such a way that no gap is left.

3. Special precautions are to be exercising doors, windows, and ventilators of strong room.

Read More

1. Plastering Method of Plastering and Different plastering techniques

2. HOW TO CALCULATE SHUTTERING AREA

3. Glazing and their types

4. Repair and building repairs related to repair

5. Stones Defination and site for Quarry with Hand Tools? Methods of quarrying

6. Timber Details of structure and Different methods of seasoning

7. Foundation and their types of Foundation

8.  Types of windows and Doors and their Specification

9. Damp ,Cause Of Dampness and Prevention of dampness