SAFETY CONSIDERATIONS FOR

USE OF GLASS IN

BUILDINGS

Usha Batra, Additional DG (Arch), CPWD, New Delhi

Dr K M Soni, Chief Engineer, CPWD, Mumbai

GLASS ON ONE HAND ENHANCES BEAUTY OF BUILT ENVIRONMENT BUT RAISES SAFETY CONCERNS ON THE

OTHER HAND

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Glass facade -structural component of building4

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GLASS AND BEAUTY

• Glass enhances the beauty ofthe building .

• Glass reduces the dead load ofthe structure

• One material with many uses -From entire facade to doorsand windows, floors towalkways, staircases to domes,canopies to skylights,partitions to enclosures,shelves to table tops andcounter-tops

LIVELIER INTERIORSCONNECTING SPACES AND OUTSIDE

It makes interiors look largerand livelier by reflecting light,illuminating surfaces,connecting spaces andconnecting inside to theoutside.

For confined spaces,glass is the preferredsolution.

GLASS IS A BRITTLE MATERIAL AND NEEDS TO BE HANDLED WITH CARE.

GLASS CAN CAUSE SEVERE INJURY

GLASS A VULNERABLE MATERIAL

Glass is one of the most vulnerable materials for accidents - insome of the locations in buildings. It may be due totransportation, cutting, installation, fall, impact, fire and evenduring occupancy due to human impact, breakage, disastersetc.Therefore, human safety due to glass becomes importantconsideration.

Glass can break during disasters and broken glass is susceptible to fall, thus in multi-storeyed structures necessary precautions are to be taken to avoid brittle failure

GLASS DURING DISASTERS

heat strengthened glass

wired glass

BREAK PATTERNS OF DIFFERENT TYPE OF GLASS

Float Heat strengthened

SHATTERED GLASS

GUN SHOTS AND BULLET PROOF GLASS

HUMAN SAFETY AND GLASS

• Glass is a material which requires to be taken duecare for human safety during

– Planning stage

– Execution or construction stage

– During maintenance stage

by architects, engineers, local bodies like fire authorities

and construction workers

ALTHOUGH GLASSIS BRITTLE, IT ISSAFE FROM FIRE,EARTHQUAKES ANDEVEN BLASTS IFONE CHOOSESRIGHT TYPE OFGLASS AND USES ITAPPROPRIATELY

SAFETY IN CONSTRUCTION

• During planning stage– Design safety– Stipulation of materials– Adoption of processes

• During construction stage– Workers safety– Safety due to materials

• During life cycle or maintenance stage– Due to fire– Due to disasters– Due to accidents

SAFETY MEASURES AVAILABLE BUT SELDOM USED AT SITE

SAFETY DEMANDS THAT PRESENCE OF GLASS IS MADE VISIBLE

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Glass being transparent,can cause head injurymistaken for openings

Addition of bandsmakes it visible andavoids accident.

TYPES OF GLASS

• Float Glass

• Tampered or Toughened Glass

• Laminated Glass

• Heat Strengthened Glass

• Fire Resistance Glass

• Insulated Glass

There are other special glasses like patterned glass,

tinted glass, frosted glass, bullet proof glass, etc.

SAFETY GLASS

• Safety glass is constructed, treated orcombined with other materials so as to reducethe likelihood of injury to persons by objectsfrom exterior sources or by these safetyglasses when they are cracked or broken.

• Toughened Safety (Tempered) Glass (TS)

• Toughened Float Safety Glass (TF)

• Laminated Safety Glass (LS)

• Laminated Float Safety Glass (LF)

SAFETY GLASSES• Toughened (Tempered) Safety Glass is a single piece of specially heat-

treated, with a stress pattern such that the piece when fractured reducesto numerous granular fragments, with no large jagged edges.

• In Laminated Safety Glass, two or more pieces of glass are held togetherby an interleaving layer or layers of plastic materials. The laminatedglass will crack and break under sufficient impact, but the pieces of glasstend to adhere to the plastic and do not fly.

• Safety Glasses are required to satisfy the relevant tests in accordancewith IS 2553 (Part 1).

• All heat-treated glasses are not safety glasses

• All laminated, toughened and safety organic coated glasses are not safetyglasses.

• Heat strengthened glasses and annealed glasses are not safety glassesunless laminated to meet the test specified for safety glass.

• Glass laminated with other than polyvinyl butyral (PVB) may not satisfythe requirement of safety glass.

SAFETY GLASS REQUIREMENTS

Test Toughened safety

glass

Laminated safety

glass

Standard to be

referred

Resistance to shock

test

Yes -

IS:2553 (Part 1) Fragmentation test Yes -

Warp test Yes -

Boil test - Yes

Fracture and

adhesion test

- Yes

Light stability test - Yes

HOW TO ENSURE - SAFETY GLASS

• Procure from certified manufacturer.

• Either a label that cannot be removed andreused or a permanent mark on the glasssurface shall mark all the panels of safety glassaccording to Bureau of Indian Standards (BIS).

• Each label must contain the ISI mark asprescribed by the BIS, manufacturers name,registered trademark or code of themanufacturer or supplier and type of safetyglass .

CRITICAL LOCATIONS

• Any glazing 1.5 metre above the floor level of a buildingis considered likely to be subjected to human impact

• Safety glazing material should also be used where thereis danger of falling infill glass materials from overheadglazing, danger of falling due to a change in floor level,and in case of balustrades, stairs and floors.

• In -and-around doors, low windows.• Panels mistaken for a doorway or opening.• Panels at low levels in walls and partitions.• Bathrooms.• Buildings associated with special activities, e.g.

gymnasia, enclosed swimming pools etc.,• Schools and child care facilities.• Nursing homes and aged care facilities.

SAFETY GLASS REQUIRED IN DIFFERENT LOCATIONS

GLASS IN CRITICAL AREAS IS UNSAFE, MUST USE SAFETY GLASS

(human impact & risk of fall)

GLASS IN CRITICAL AREAS IS UNSAFE, MUST USE SAFETY GLASS

(human impact & risk of fall)

USE OF TOUGHENED GLASS MUST FOR CRITICAL AREAS (human impact)

CO-RELATION BETWEEN MAXIMUM GLASS AREA AND GLASS THICKNESS

(IMPACT LOAD)

• Maximum Permissible area of Safety Glass as

well as annealed glass corresponding to

thickness and supporting conditions i.e 4,3,2

sides etc. are available (AS:1288-2006) upto

7.5sqm

• In cases beyond 7.5 sqm. IS : 875 (Part 3) :1987

(Reaffirmed 1997) is to be referred for external

glazing.

PRECAUTIONS AGAINST GLASS FALLING ON PEOPLE

• Broken annealed glass falling on people can cause grievous or even fatal injuries;hence it is recommended to use safety glass in locations other than defined incase 1 where the risk of people getting hurt by falling glass is high.

• Toughened (tempered) glass due to safe breakage pattern breaks anddisintegrates into small and relatively harmless particles. However thicktoughened glass particles may stay interlocked and fall as lumps of these multipleparticles and can cause a minor or medium injury mainly due to the weight of thecluster.

• Laminated safety glass will generally not fall out of fixing. However, wherelaminated glass with both glasses toughened, is used for horizontal or slopedglazing, in case of failure of both toughened glasses, it may crumple as a blanketand fall out of fixing in the event of failure of both toughened glasse. Therefore,Strength of the glazing system should be such that it has the ability to holdglass in place and prevent it from falling out as a whole.

• If Insulating Glass Unit (IGU) is used in situations mentioned above, then criterionwill be followed if IGU is installed in areas subjected to human impact on eitherside then both the panes of the unit shall be provided with safety glass and insituations where access is restricted to one side of the unit, then only theaccessible side should be provided with safety glass .

PRECAUTIONS DURING HANDLING, TRANSPORTATION, CUTTING AND

FIXING OF GLASS

• It should be ensured in multi-storeyed buildings havingstructural glazing that framework is properly designedand is rigidly fixed to the structure.

• Selection of glass to be based on location, size, breakagecharacteristics, type of the building and its use, inparticular the number of the people expected to be inclose proximity to the glass in critical locations,requirements for fire, security ,wind loading, thermalbreakage, energy efficiency and deflection, vision,acoustics and other consideration and impact of trolleys,carts, luggage etc .as per the use.

• Presence of glass doors must be made apparent .• Installation procedures, must be followed as per BIS.

PRECAUTIONS FOR USE OF

GLASS FOR FIRE SAFETY • Fire rating of the glass needs to be considered as per the codal

requirements from fire safety as well as from evacuationconsiderations.

• Sufficient side hung openings/windows need to be provided forfireman to evacuate trapped people .These openable portions haveto be left at regular distances for firefighting and smoke exhaust.

• Alternatively, knock-out panels are to be provided with temperedglass to allow fracturing of the glass into small pieces, identified bya non-removable reflective dot (typically 5 cms in diameter) locatedin the lower corner of the glass to be visible from the ground by thefire fighters.

• Space between the slab and façade to be provided with fire stopsand fire rated GI backup panel to stop fire traveling from one floorto another.

• Glass proposed to be used for internal fire compartmentationshould either be low radiation (Class EW) or insulated fire ratedglass (Class EI) conforming to National Building Code of India 2005.

FIRE RESISTANT GLASS

Glass can actually substitute a brick wall in terms of fire-rating property while maintaining transparency.

• Wired Glass • Borosilicate Glass • Toughened Glass with flame retardant coating • Toughened Glass with Intumescent gel • Laminated Glass with Intumescent layers.

FIRE PROTECTIVE AND FIRE RESISTIVE GLASS

FIRE RESISTANCE GLASS

FIRE RATED DOOR FOR FIRE SAFETY38

CONCLUSIONS• Looking at the increase in use of glass in building industry,

human safety has become the main concern.• Glass, no longer, remains a general product but a tailor

made product to be designed and selected based on itslocation, site requirements, functional requirements, firesafety requirements and overall human safetyrequirements during its applications and thereafterduring life cycle of the structure.

• It is utmost important to select the right type of glass, itsappropriate thickness and complete glazing system.

• To minimise accidents, it is onus on the Architect /designer to appropriately use the quality of transparencywhile designing so that presence of glass is made visible.

• Due to increase in fire accidents, all the provisions for firesafety must be mandated and strictly followed.

(Considerable material and photos have been taken from various websites and CCPS guidelines. The contribution is gratefully acknowledged)