Building Construction 10

Dr Nabil El-Sawalhi

Associate professor

Engineering Projects Management

Surface Finishes

• Functional requirements

– Provide a durable, visually attractive and low-maintenance surface to floors, walls and ceilings.

• There may be differences between the functional requirements of the external and internal finish

External Finishes

• Important in determining the aesthetic appeal of the building.

• Determine how the building will weather over time.

• The quality of the materials used for external finishes and the manner in which they are applied will determine the durability of the building.

• The functional requirements are:

• ❑ Aesthetic appeal

• ❑ Durability

• ❑ Strong mechanical or chemical bond to structural substrate

• ❑ Flexibility, the ability to withstand thermal and moisture movement (via control joints)

• ❑ Health and safety considerations

Internal Finishes

• Creating a sense of place and in helping to ensure a healthy indoor environment.

• As we spend a great time within buildings, the quality of the internal environment is particularly important in ensuring a sense of well-being and enjoyment.

• Materials will be touched, experienced visually and will give off scent, which, combined with furnishings and appliances, will influence our perception of the space and affect indoor air quality.

• The functional requirements of internal finishes are: • ❑ Aesthetics • ❑ Durability and flexible ability to withstand thermal

and moisture movement • ❑ Ease of maintenance and cleaning • ❑ Strong mechanical or chemical bond to structural

substrate • ❑ Expel water from the surface that forms as

condensation • ❑ Prevent and resist mould growth or insect attack • ❑ Provide visual finish, high levels of contrast (e.g.

nosing on stairs) • ❑ Tactile or touch-sensitive finish as an aid to those

with visual difficulties • ❑ Non-toxic

Types of finish

• There are two different types of finish to the building fabric:

– inherent in the material and

– applied to a background.

Inherent Finishes • Many materials such as timber, stone, brick and glass

provide a natural finish without any need for further work – an inherent finish.

• Carefully chosen, materials with an inherent finish may help to reduce construction time and initial construction costs.

• The use of materials with an inherent finish may be an important consideration when disassembling the building and reclaiming materials at a future date for reuse, since the material has not been compromised by the application of a finish.

Applied Finishes: ecological consideration

• Application of materials to existing backgrounds, such as plaster or render to a wall, or paint to timber, is an applied finish.

• The durability of the finish will depend upon:

– the material properties of the finish

– the material it is applied to,

– the bond between the two materials.

• Ecological design goals aim to minimize the pollution from applied finishes.

• Petrochemical paints, stains and varnishes should be avoided

• Preference given to products with natural pigments that are not harmful to animals, plants or people.

• Frequency of maintenance and re-application of applied finishes needs to be considered in the overall life cycle of the building, and compared against inherent finishes.

Floor Finishes

• There is a wide range of finishes available from which one may be selected as best suited to a particular function.

• For the small floor areas of rooms in houses and flats, the choice of floor finish is dictated largely by appearance and ease of cleaning.

• For the larger floor areas of offices, public and institutional buildings, ease of cleaning is a prime consideration where power-operated cleaning and polishing equipment is used.

Finishes to concrete floors

• It is convenient to make a broad general classification of finishes to concrete floors

• ❑ Jointless

• ❑ Flexible thin sheet and tile

• ❑ Rigid tiles and stone slabs

• ❑ Wood and wood based

Joint-less floor finishes

• This group includes:

– Cement- and resin-based screeds

– mastic asphalt.

• These are laid while plastic and other than the provision of movement joints they provide a homogeneous surface.

Cement screeds

• A cement- and sand-screed finish to a concrete floor may be an acceptable, low-cost finish to small area floors of garages, stores and outhouses where the small area does not justify the use of a power float and considerations of ease of cleaning are not of prime importance.

• To produce improved surface resistance to wear and resistance to the penetration of oils and grease, a dry powder of titanium alloy with cements may be sprinkled on to the wet surface of concrete or screed and trowelled in.

Granolithic paving • Granolithic paving consists of a mixture of crushed

granite, which has been carefully sieved so that the particles are graded from coarse to very fine

• The usual proportions of the mix are 2½ of granite chippings to 1 of cement by volume.

• These materials are mixed with water and the wet mix is spread uniformly and trowelled to a smooth flat surface.

• When this paving has dried and hardened, it is hard wearing.

• This floor finish is used for factories, stores, garages

Resin-based floor finish • A range of resin emulsion finishes is available for use

where durability, chemical resistance and hygiene are required in laboratories, hospitals and food-preparation buildings.

• This specialist application finish is composed of epoxy resins as binders with cement, quartz, aggregates and pigments.

• The material is spread on a power-floated or cement-screed base by pumping and trowelling to a thickness of up to 12 mm.

• The aggregate may be exposed on the surface as a non-slip finish and as decoration.

• On larger floor areas, it is used for the advantage of a seamless finish that can be cleaned by a range of power-operated devices.

Flexible thin sheet and tile

• Linoleum is made from oxidised linseed oil, rosin, cork or wood flour, fillers and pigments compressed on a jute canvas backing.

• The sheets are made in 2 m widths, 9–27 m lengths and thicknesses of 2.0, 2.5, 3.2 and 4.5 mm in a variety of colours.

• The usual thickness of the sheet is 2.5 mm. • Tiles 300 and 500 mm square are 3.2 and 4.5 mm thick • Linoleum should be laid on a firm level base of

plywood or particle board on timber floors or on hardboard over timber-boarded floors and on a trowelled screed on concrete floors

Flexible vinyl sheet and tiles

• Polyvinyl chloride (PVC), generally referred to as vinyl, is a thermoplastic used in the manufacture of flexible sheets and tiles as a floor finish.

• Used where consideration of cost and ease of cleaning combine with moderate resistance to wear.

• Sheet thicknesses from 1.5 to 4.5 mm in widths from 1200 to 2100 mm are produced in lengths of up to 27 m.

Pre-cast terrazzo tiles

• Pre-cast terrazzo tiles are widely used as floorings in residential, commercial, and institutional buildings.

• Tiles are manufactured in square sizes varying typically from 10 cm x 10 cm up to 40 cm x 40 cm, mechanically vibrated in the mold, hydraulically pressed, water or air cured, then grit polished before being shipped to site.

• Final polish is performed in situ after setting and leveling the pre-cast tiles on a sand bed.

• Rigid stainless steel molds used in the manufacture of the tiles are filled manually or automatically with the marble chips then sufficient amounts of white cement grout are poured to fully enclose the marble chips followed by a backing layer of Portland cement mortar in measured quantities.

• The molds are then vibrated and the mix is hydraulically pressed to the required pressure for a few seconds before being released.

• The tile is then de-molded and stored for curing. Automatic or manually operated equipment can be used.

• Tiles Dimentision • 20x20x2cm • 25x25x2.5cm • 30x30x3cm • Tiles standard tests • 1. Absorpation test • 2.Abraion test • 3.Transverse strength on dray tiles • 4. Transverse strength after 24 hr immersion in

water (Wet tiles)

Floor quarries(Unglazed Ceramic)

• Floor quarries are manufactured from natural clays.

• The clay tile is then burnt in a kiln.

• Manufacturers grade tiles according to their hardness, shape and colour.

• Quarries shrink appreciably when burnt, and there may be a noticeable difference in the size of individual tiles in any batch.

• The usual colours are red, black, buff and heather brown.

• Some common sizes are 100 × 100 × 12.5 mm thick, 150 × 150 × 12.5 mm thick and 229 × 229 × 32 mm thick.

Glazed Wall Tiles

• Internal Glazed Wall Tiles • The body of the tile can be made from ball-clay,

china clay, china stone, flint and limestone. • The material is usually mixed with water to the

desired consistency, shaped and then fired in a tunnel oven at a high temperature (1150C) for several days to form the unglazed biscuit tile.

• The glaze pattern and colour can now be imparted onto to the biscuit tile before the final firing process at a temperature slightly lower than that of the first firing (1050C) for about two days

• Typical Internal Glazed Wall Tiles and Fittings Sizes –

• Modular 100 x 100x 5 mm thick and 200x 100 x6.5 mm thick.

• Non-modular 152x152 x5 to 8 mm thick and 108x108 x4 and 6.5 mm thick.

• Other sizes – 200x300, 250 x330, 250x 400, 300x 450, 300x 600 and 330x 600mm.

• Fittings- wide range available particularly in the non-modular format.

• Bedding of Internal Wall Tiles

– generally glazed internal wall tiles are considered to be inert in the context of moisture and thermal movement, therefore if movement of the applied wall tile finish is to be avoided attention must be given to the background and the method of fixing the tiles.

• Backgrounds of tiles

• these are usually of a cement rendered or plastered surface and should be flat, dry, stable, firmly attached to the substrate and sufficiently established for any initial shrinkage to have taken place.

• The flatness of the background should be not more than 3 mm in 2 m for the thin bedding of tiles and not more than 6 mm in 2m for thick bedded tiles.

• Fixing Wall Tiles

• two methods are in general use:

• 1. Thin Bedding: lightweight internal glazed wall tiles fixed dry using a recommended adhesive which is applied to the wall in small areas 1 m2 at a time with a notched trowel, the tile being pressed into the adhesive.

• 2. Thick Bedding: cement mortar within the mix range of 1:3 to 1:4 can be used or a proprietary adhesive, either by buttering the backs of the tiles which are then pressed into position or by rendering the wall surface to a thickness of approximately 10 mm and then applying thin bedded tiles to the rendered wall surface within two hours.

• Grouting

– when the wall tiles have set, the joints can be grouted by rubbing into the joints a grout paste either using a sponge or brush.

– Most grouting materials are based on cement with inert fillers and are used neat.

Clay floor tiles

• Where finely ground clay is used, the finished tiles are very uniform in quality

• They are used for kitchens, bathrooms and halls where durability and ease of cleaning are an advantage.

• Some common sizes are 300 × 300 × 15 mm thick, 150 × 150 × 12 mm thick and 100 × 100 × 9 mm thick.

Concrete tiles • Concrete tiles made of cement and sand, which is

hydraulically pressed to shape as floor tiling, have been used as a substitute for quarry and plain colour clay tiles.

• The usual size of tiles is 300 × 300 × 25 mm, 225 × 225 × 19 mm and 150 × 150 × 16 mm.

• The material may be pigmented or finished to expose aggregate.

• The density and resistance to wear depend on the quality control during manufacture and the nature of the materials used.

• They are laid on a level power-floated concrete or screed surface and jointed in the same way as quarries and plain colours.

Joints • The width of the joints between tiles and slabs as an

internal floor finish is determined by the uniformity of shape of the material used.

• For quarries, joints of up to 12 mm may be necessary to allow for the variations in size, and joints as little as 1 mm may be possible with very accurately cut and finished thin slabs of granite and marble.

• The disadvantage of wide joints is that the material used, such as cement and sand for quarries, will be more difficult to clean and will more readily stain than the floor material.

• Ideally, the jointing material should have roughly the same density, resistance to wear and ease of cleaning as the floor finish.

Control joints

• The joints between tiles and slabs will serve the purpose of accommodating some movement of the floor finish.

• Some small expansion or contraction of the floor finish will be taken up in the joints through slight cracks or crushing of the very many joints.

• It is good practice to form control joints to accommodate structural, moisture and thermal movement.

Timber floor finishes

• Wood strip flooring Strips of hardwood or softwood of good quality, specially selected so as to be particularly free of knots, are prepared in widths of 90 mm or less and 19, 21 or 28 mm in thickness.

• There is always some tendency for wood strips to twist out of true due to the wood drying out, and to resist this, the strips have to be securely nailed to wood battens which are secured to the concrete floor, either by means of plugging and screwing the battens to the structural concrete

Wood block f loor f inish

• Blocks of wood are used as a floor finish where resistance to heavy wear is required, as in halls, corridors and schools, to provide a surface which is moderately resilient, warm and quiet underfoot.

• An advantage of the comparatively thick blocks is that after wear, the top surface may be sanded to reduce the block to a level surface.

• The blocks are usually 229–305 mm long by 75 mm wide by 21–40 mm thick, and are laid on the floor in a bonded, herringbone or basket weave pattern.

• The usual patterns are illustrated in Figure 10.3.