FLOORS

FLOORSBy Chakamba john

Definition

A Floor is a horizontal structure which carries imposed and live loads in a building or divides a building into storeys (Obande,1996).

A solid base of a room

PURPOSES OF FLOORS

To support live and dead loads

To divide high rise buildings into storeys

FUNCTIONAL REQUIREMENTS Strength and stabilityResistance to weather and ground moistureDurability and freedom of maintenance Fire safetyResistance to the passage of heatResistance to the passage of sound

Functional requirementsGround floorsTo withstand the loads imposed upon them (e .g., people, furniture)To prevent vegetable matter from growing inside the building, by provision of over site concreteTo prevent damp penetration into the building by inserting damp proof membrane in the floor

To meet prescribed thermal insulation standards by incorporating a layer of insulating material to reduce the heat loss into the ground below itTo be reasonably durable and so reduce amount of maintenance or replacement workTo provide an acceptable floor finish which meet needs of users with regard to appearance, comfort, safety, cleanliness etc.To provide a level surface for people

TYPES

There are two types of floors namely

Upper floorsGround floors

GROUND FLOORSThe two types of ground floors are

Solid ground floorSuspended ground floor

Upper floorsAre floors that divide a building into storeys.Functional requirementsTo support their own weight, ceilings and superimposed loadsTo restrict the passage of fireSound insulation

DurabilityTo bridge the specific span economically and be capable of quick erectionTo accommodate services readilyTo provide an acceptable surface finish

Solid ground floorHas the whole of its area direct contact with the subsoil.Is made out of a concrete slab laid on AdvantagesCheaper on fairly level sitesMay reduce quantity of wallingReduce heat loss through the floorAvoid the risk of dry rot Offer a greater selection of floor finishes

Components of solid ground floor

Hardcore a layer of hard material put before laying the over site concrete must be 150mm thick purposes-to create a level and firm base for concrete slab-reduces capillary action-it fills up low areas created after the removal of topsoil Materials used for hardcore -broken bricks, tile rubble, clinkers, colliery shale, gravel, quarry waste, and pulverized fuel ash,stones

Over site concreteis the over site bed of concrete which is placed on top of hardcoreit should not be less than 100mm thick.mix of concrete can be 1:3:6 if its mass and 1:2:4 when reinforced. can be left rough, wood or steel float finish PURPOSETo provide a suitable base on which a desired floor finish can be applied

Damp-proof membrane(dpm)A polythene sheet or a coating of bituminous felt or asphalt-prevent passage of moisture into the building through the floor.Is normally lapped with dpc in the surrounding walls-dpm must be -:impermeable to water.continuous with damp-proof course in adjoining walls.tough enough to remain undamaged when laying the screed or finish.-suitable materials for dpm are-mastic asphalt, bitumen sheets and polythene sheets.

Blinding

Is a layer of weak concrete or river sand of a depth of 40mmIt is meant to prevent piercing of dpm by hardcore or over site concrete

Floor screedsFunctionsTo provide a smooth surface to receive the finishTo bring a number of floor finishes each of different thicknesses up to the same finished levelTo provide falls for drainage purposesTo provide thermal insulationTo accommodate service pipes and cables.-cement sand screeds mix of 1:3 is recommended-thickness of floor screed is usually 25-75mm.

Methods of constructing floor screeds1.Monolithic construction-is when a screed is laid on an in situ concrete base before it has set (within 3hrs of placing).-complete bonding is obtained and the minimum thickness should be 15mm.

2.Bonded construction-the screed is applied after the base has set and hardened.-maximum bond is secured by hacking, cleaning and damping the surface of concrete, then apply wet cement grout before screed is laid.-thickness of screed should be at least 40mm.

4.Floating-screeds are laid in bays of at most 15m.-edges of bays should be vertical.-screed is laid on a compressible layer of thermal or sound insulating material such as compressed board.Curing-A screed should be cured for at least 7 days after laying.-methods-covering with polythene sheet or water proof paper and sprinkling water

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SUSPENDED GROUND FLOORSConsist of boarding nailed to floor joist which are laid on timber plates running in the opposite direction and bedded on brick sleeper walls built off over site concrete.

Requirements of suspended ground floorshould be above highest level of adjoining ground.

As approved by the Building Regulations Document C4(1991);The ground surface to be covered with a layer of concrete not less than 100mm thick.Ground surface concrete cover can be at least 50mm thick if laid on polythene sheet.Top surface of concrete

Timber floor boarding

Suspended timber floors may be covered with timber boards or strips or sheet of chip board.Boards are usually 100-150mm wide with thickness of 25mmBoards are laid at right angles to joists.Floor boards are normally joined with tongue and grooved joints.

Tongue and groove boarding(T&G Boarding)

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-when boarded floor is required T&G boards are recommended for both suspended and for solid floors.-use of T&G boards prevents splitting of the boards due to draughts that may pass through between the joints. -For strip flooring and where the boarding provides the floor finish, secret nailing may be used so that nails do not show on the surface . In this case splayed tongue and groove is preferred.-The diagram below shows splayed T&G boarding:

Tongued and grooved boards

FLOOR FINISHESFunctional requirementsDurability- the material must have a reasonable life to avoid premature replacement.Resistance to wear-floor finish should match type of wear in the specific part of the building so as to last long without replacement.Economy-reasonable initial and maintenance cost.Resistance to oil, grease and chemicals-should not be damaged by grease and oil spills and they should be easy to remove from the floor. Spills are a particular problem in kitchens, bathrooms and laboratories.Resistance to moisture-should resist to water spills and this is important in kitchens, bathrooms, entrance passages and halls.Should be easy to clean.

7.Warmth or coolness-hard smooth surfaces are cool to walk because they reflect heat away. Soft textured finishes like carpets provide warmth which may be suitable for cooler climates.8.Sound insulation-hard surfaces do not absorb sound so they are noisier than soft surfaces. Buildings like hospitals and libraries need floor finishes with high degree of sound absorption.9. Cost-this has a bearing capacity of the pocket. Generally a simple cement finish is cheaper than carpet, wood bock or special floor tiles.10.Non slip qualities-especially in bathrooms and kitchens where floors may be damp.11.Appearance-attractive floor finishes are needed for many rooms of domestic buildings.

Classification of floor finishesCan be divided into four groups namely

Stone floor finish eg concrete ,terazzo,granolithic

Wood floor finish eg strip and board, wood block, parquate and mosaic

Sheet and tile eg rubber, mastic asphalt, pitch mastic, pvc ,thermoplastic

Carpert eg light domestic,medium

GRANOLITHIC FINISHA mixture of river sand and cement laid on wet or dry concrete subfloorSuitable for heavy duty industrial floors, domestic entrances, verandas and church floors

ADVANTAGESIt is cheap to constructhardwearing

DISADVANTAGESIt is generally cold and unattractive

Granolithic floor finish

TERRAZOA decorative form of concrete made from Portland cement and crushed marble aggregate and polished using a fine abrasive stone

PROSAttractive in appearanceHardwearingEasily cleanedResistant to chemical attack

CONSNoisyColdExpensive

Terrazzo floor finish

3.Carpet-One of the most important finishes and is widely used in domestic properties and public areas of commercial buildings.-A wide variety of qualities exist and expert advice is required on selection.-Quality is dependent on the yarn, construction, backing and density.-Carpets should always be laid in dry situations and a suitable underlay (foam rubber or cotton waste) and at times should be secured by suitable adhesives, nailed around the perimeter.

Carpet GradingLIGHT DOMESTICFor rooms subject to light traffic-bed rooms; guest roomsMEDIUM DOMESTICFor rooms subject to light traffic-lounges, dining rooms, hotel bed roomsHEAVY DOMESTICRooms corridors subject to heavy trafficMEDIUM CONTRACTFor offices, shops, hotel bars, lounges subject to heavy trafficHEAVY CONTRACTAreas subjected to very heavy traffic and frequent cleaning-public buildings, theatres, hotel/shop entrances, hospital corridors

Carpet floor finish

PropertiesQuietWarmResilient- durable, stain and water resistanceNon slip

RUBBER TILES AND SHEETSMade from natural or synthetic rubberNormally 2-4mm thick for domestic buildings and 4-6mm for public buildingsThe floor finish must be fixed with a suitable adhesive

MERITSQuiet Warm Non slipResilient Resistant to moisture, acids, oils and fats

Rubber floor finish

Flexible PVC tiles

oilsWater proofDurablePopular for domestic, commercial and industrial interior.They are laid on a suitable adhesive preferably bitumen adhesive. These have precise measurements (3003003mmthick)PropertiesResistant to grease and

PVC tiles come in a wide range of colors and textures and are one of the cheapest floor finishes one can buy and lay.They are maintained by applying a surface coating of wax and the washing with soapy water. prosAttractiveSmoothCoolWaterproofDurableResistant to grease and oilsCan be repaired very easily as they are made in small square units

Pvc floor finishes

Clay tiles

-Two main types are floor quarries and ceramic floor tiles. They provide hard semi glazed finish.-They usually measure about 150mm150mm or 100mm100mm and are 15 to 20mm thick and are laid in mortar.-They are cold, noisy and expensive.

Clay tiles floor finish

Wood mosaic / parquet flooring

Consist of fingers of hardwood arranged in groups to form 115mm squares laid to form simple basket weave pattern. This finish can easily be affected by moisture

Provides a warm, decorative, resilient and durable flooring

Wood parquets floor finish

Stone - most suitable floor finish for entrance halls and public bars as these places are subjected to heavy foot traffic. Below is stone floor finish;

Brick-Suitable for kitchens, toilets and entrance halls.

Wood strips-where 150 to 380mm(length) strips of wood are laid in tongue and groove jointing.-are often laid to herringbone or basket weave patterns with surface of blocks sealed and waxed.-Thickness vary from 20mm to 38mm.Properties- warm, quiet, resilient, attractive, hardwearing.

Wood blocks floor finish

Wood blocks floor finishes