BRICKLAYING

BAGGED OR RUBBED JOINT: A flat mortar joint finish often lightly wiped over with sacking. This should not be used to achieve a neat decorative finish.

BATS: Broken bricks or purpose cut bricks, which are used to fill in.

BLOCKS: Light or dense concrete blocks are generally used in masonry that is hidden such as within the inner skin of cavity work. They may, however, be used ‘architecturally’ in public buildings. Blocks most often measure 440 x 215mm, which is equivalent to 6 standard bricks. Lightweight blocks have insulation properties and are often made from aerated concrete where pulverised fuel ash is the aggregate. These are usually referred to as breeze blocks and common trade names include Theralite and Celcon. Harder concrete blocks may have hollow centres which can be filled with foam insulation. Very dense concrete is used in heavy load bearing blocks, which can be up to 225mm thick. These can be quite heavy to lift and require care when laying to avoid squeezing out the mortar.

BONDING: The general term given to the pattern of bricks laid or the method used to join new walls.

BRICK: A standard brick will measure (mm) 215(length) x 102(width) x 65(height). Builders will always request to see designs in brickwork sizes to avoid part cuts.

BUCKET HANDLE: A shallow, rounded and inwards mortar joint finish used for bricks and blocks, so named as it was originally created from the shape of an old bucket handle.

CAVITY: The outer brickwork is in place to keep out the weather and usually has no structural implications. The inner blockwork carries the floor and roof loads. The gap between prevents damp crossing. It is important to maintain a cavity that is clear and unbridged.

DAMP: The short name for a damp proof course originally made from slate, lead or bitumen treated hessian. This was prone to melting in warm weather and has now been replaced with high performance plastic. The damp proof course may be inserted in brickwork to stop damp rising or sinking. If at high level, the latter is usually accompanied by a flashing. In garden walls, the damp course is located beneath the top of the wall, often as a tile, to prevent the wall becoming saturated and damaged by frost. In house walls, the damp proof course is usually placed 150mm above ground level. This distance must be maintained to avoid damp being transferred through rain splashing.

EFFLORESCENCE: Natural salts, which occur in the material used to construct bricks, will sometimes be washed out by rain and appear as white stains. Although this is of no consequence to the wall’s integrity, it is always disappointing and unsightly. Before choosing any brick, take care to find out if this is a feature of the brick and look at examples that have been in place for between 2 and 5 years.

FACE WORK: The out facing side of brickwork that will be on show and will consequently need to be built neatly.

FLEMISH: A brickwork bond where the stretcher face is alternated with the header face on the first line and on the course above, the header is positioned over the centre of the stretcher face below, so that the courses alternate.

GAUGED MORTAR: Mortar produced from sand and cement mixed with lime to produce a lower strength, more workable mix. This is well suited to softer bricks and useful where minor movements in walls may show up as cracked bricks if a hard mortar is used.

HAND MADES: Bench made stock bricks, where the soft clay from south-eastern England is thrown into the pre-sanded mould by hand. The finished effect will be horizontal ripples, most often mid-to-dark red with blue markings.

HEADER: The end of a brick. If laid together, this would be referred to as a header course.

LINTEL: A concrete or steel beam positioned over doors or other openings to support the bricks/blocks above.

MUCK: Nickname for mortar.

PERPS: Perpendicular ends to bricks. If you look at the outside of a completed wall, the line and verticality of the perps is a good indication of the quality of bricklaying.

PUG: Nickname for mortar.

QUOINS: Right angle corners of brickwork that are built up at the start of the job to form the brick lines and courses. Less experienced bricklayers will sometimes fill-in between the quoins.

RUBBERS: Soft red bricks that can easily be cut to shape, such as within an arch. These bricks should always be used with a soft lime mortar.

SAND-LIMES: Calcium silicate bricks which are almost white in colour. Trouble may be experienced with spalling (the breaking up of the face of bricks), particularly if exposed to salt or frost.

STOCKS: Bricks made in a mould either by hand or machine. The bricks are soft and mostly used in face work. The hand made bricks usually have a rippled appearance. Stocks usually have a frog, which is the indent on one long side. ‘Frog up’ is the normal method of laying. The Romans brought the stock brick to England.

STRETCHER: The long face of a brick. Stretcher bond is the most common bonding where each brick is laid length ways in the wall, with the joint of the course above in the centre of the stretcher face.

STRUCK JOINT: A mortar joint usually on brickwork, requiring a good level of skill to achieve neatly. The mortar is ruled smooth with a small trowel so that the top is slightly in from the brick face and the bottom is flush with the brick face. Sometimes this is reversed but, in doing so, water may be trapped on the small ledge formed. This joint attracts shadow lines and can look the neatest.

TIES: A steel, galvanised or better stainless, link between inner and out skins (see cavity).

WIRE CUTS: This is an extruded brick of modern style with a slightly dragged appearance, which is chopped to size with wire. Instead of frogs, wire cut bricks tend to be perforated on the mortar faces.

CARPENTRY

BALUSTER: The slim posts located under the handrail in a staircase, commonly termed banisters.

CASEMENT: A window that has hinged opening sashes.

CUT NAIL: A large flat nail stamped out of a sheet of soft steel, mostly used for fixing timber to lightweight blocks.

DEAL: A term often ambiguously used to describe softwood. The correct meaning is a size of squared timber measuring between 2 and 4 inches thick and 9 and 11 inches wide.

GRADED: Regularity or strength graded.

HARDWOOD: Wood from deciduous broad-leafed trees such as oak, beech, mahogany and maple. Rarely used structurally nowadays. The cell structure makes it difficult to absorb preservatives.

JOIST: Structural member running horizontally and supporting a ceiling or floor.

MUNTIN: The vertical strut of a window frame or a glazed doorframe which sits between panes.

NEWEL: The vertical post at the top and bottom of a staircase where the handrail is jointed.

PAR: Prepared all round, i.e. planned timber.

PURLIN: A horizontal roof member located part way up a rafter. The purpose of the purlin is to prevent the rafter from sagging under load and, in turn, the purlin may be supported by posts to transfer the purlin loads onto internal walls below and so to the foundations. This will prevent the outer walls from bearing all the roof loads.

RAFTER: The structural member of a roof which supports the weathering materials underneath. It would still be called a rafter in a flat roof.

RISER: The vertical part of a stair step.

SASH: The opening part of a window.

SHAKES: Splits in wood, usually running with the grain, caused by shrinkage through excessive or rapid drying.

SOFTWOOD: The wood of (mostly) conifer trees such as pine, fir, cedar, larch, spruce, etc. Sometimes also referred to in the different types as hemlock, whitewood and redwood. Most of this wood is resinous and has natural water resistance. The woods are less prone to shrinkage than hardwoods. Some of the softwoods (such as yew) may be physically harder than some hardwoods (such as ash).

STILE: The vertical edge parts of a doorframe. The hinge side is the hanging stile and the opposite side, the lock stile.

STRING: The side of a stair where treads, risers and balusters are fitted.

TANALISED: A highly toxic propriety blend of copper and arsenic which is pressure-impregnated into softwood as a preservative.

TRANSOM: The horizontal member of a window frame.

TREAD: The horizontal part of a stair step.

TRUSSED ROOF: A pre-site manufactured roof member in a triangular shape, in which comprises rafters, struts and joists. Factory jointed with metal or plywood plates. The members are comparatively slim and it is important not to remove any part without specialist advice.

WINDER: A turning tread in the stair.

WROT: Planed timber.

PAINTING and DECORATING

ACRYLIC FILLER: Gap and surface fillers that remain highly flexible when cured to allow movement. These are particularly good for ceilings and junctions of wood to plaster.

ALKYD: Oil paint made from synthetic resin instead of natural oils.

ANAGLYPTA: A trade name, which is now used generically to describe wallpaper that has patterns or bubbles embossed in the surface.

BLEEDING THROUGH: Paint applied over a solvent will be gradually dissolved and show stains. Solvents responsible for this would typically be wood resin, chimney tars (leeched out by damp walls) and cooking oils. To avoid this, a solvent resistant undercoat, such as knotting, must be used.

BROKEN PAINT: Usually oil paint applied in layers of different colours or tints, which is brushed or combed into patterns of wood grain, marble or weave.

CHROMATE: A primer paint used for galvanised surfaces.

DISTEMPER: A traditional unstable wall paint comprising water, pigment and glue that pre-dated emulsion.

EGG SHELL: An oil -based paint that dries semi matt but retains the strength of gloss.

EMULSION: A paint where the solvent is water and the oil content is mixed with a medium that disperses the oil into minute droplets that can be held in the water as a liquid but reform to a hard surface when the water evaporates.

GRINNING: Where paint has been applied too thinly over darker surfaces, the surface below may show or grin through.

KNOTTING: A mixture of varnish where the solvent is methylated spirits so the coating is not dissolved by wood resin. It is applied onto bare wood over knots or resin pockets.

LINING PAPER: A wallpaper used to cover poor surfaces prior to applying paint or wallpaper.

MIST COAT: A diluted first coat plaster which is applied to seal the absorbent surface and highlight areas to be filled.

OILS: Paint in which the pigment is bound by oil such as linseed and tung. This is very hard wearing but gives off a strong odour and brushes can only be washed in white spirit.

PLUMBATE: Lead-based paints, which are poisonous and so, require special care. The paint is used as a primer for steel and has good corrosion resistance.

SIZE: A thin mixture of water and glue, which is brushed onto absorbent or new walls to seal the surface and prevent absorption. This has been replaced by primer/sealers but the process may still be referred to as sizing.

STABILISER: An oil bound paint that has high absorption properties and strong resin binders similar to alkyds. The paint is applied as a preparation to flaking or dusty surfaces.

VINYL MATT/SILK: An emulsion paint with good wearing and cleaning properties.

WOOD CHIP: A two-layer wallpaper with wood chippings sandwiched between the layers. This is used to cover poor surfaces and to hide undulations.

ACRYLIC FILLER: Gap and surface fillers that remain highly flexible when cured to allow movement. These are particularly good for ceilings and junctions of wood to plaster.

ALKYD: Oil paint made from synthetic resin instead of natural oils.

ANAGLYPTA: A trade name, which is now used generically to describe wallpaper that has patterns or bubbles embossed in the surface.

BLEEDING THROUGH: Paint applied over a solvent will be gradually dissolved and show stains. Solvents responsible for this would typically be wood resin, chimney tars (leeched out by damp walls) and cooking oils. To avoid this, a solvent resistant undercoat, such as knotting, must be used.

BROKEN PAINT: Usually oil paint applied in layers of different colours or tints, which is brushed or combed into patterns of wood grain, marble or weave.

CHROMATE: A primer paint used for galvanised surfaces.

DISTEMPER: A traditional unstable wall paint comprising water, pigment and glue that pre-dated emulsion.

EGG SHELL: An oil -based paint that dries semi matt but retains the strength of gloss.

EMULSION: A paint where the solvent is water and the oil content is mixed with a medium that disperses the oil into minute droplets that can be held in the water as a liquid but reform to a hard surface when the water evaporates.

GRINNING: Where paint has been applied too thinly over darker surfaces, the surface below may show or grin through.

KNOTTING: A mixture of varnish where the solvent is methylated spirits so the coating is not dissolved by wood resin. It is applied onto bare wood over knots or resin pockets.

LINING PAPER: A wallpaper used to cover poor surfaces prior to applying paint or wallpaper.

MIST COAT: A diluted first coat plaster which is applied to seal the absorbent surface and highlight areas to be filled.

ELECTRICS

5 AMP CIRCUIT: A low power circuit for lighting, most commonly used for task and table lamps and now largely discontinued.

BONDING: All metal pipes in buildings must be earthed electrically by linking them all together with wires, which are then connected to earth. This is done to prevent severe electrical shock to persons should the pipes become live through a fault.

CIRCUIT BREAKER: A switch that replaces a fuse to protect from electrical overload. If the circuit breaker is activated, pushing in the button can reset it but the reason for activation should always be investigated, especially if there is a repeat.

CONSUMER UNIT: The panel beside the meter on the consumer side of the meter, which contains fuses or circuit breakers.

EARTH LEAKAGE: This has the same function as RCD in cutting the power if minute currents are detected.

FLEX: Cable where the electrical conductor core is made up of many fine strands instead of the single wire as in twin and earth.

FUSE: The thin wire in a carrier which protects an electrical circuit. Fuses occur as a cartridge or loose wire.

MEGGER: A testing meter used to check the resistance of electrical circuits, particularly earths, through a small power source which sends several thousand volts at very low power through the circuit.

RCD: Residual current device or breaker on the board beside the main fuses or circuit breakers. This can also be a local device switch as a socket or plug-in. The device monitors the earth and if it finds any current which has crossed from the live side, it switches off the power in a split second, thereby protecting persons from electrical shock.

RING: The power circuit to sockets is found in the form of a wire looped from socket to socket and back to the circuit breaker to save on wire. This is known as a ring.

RADIAL: Similar to a ring but fed from one end only.

TWIN AND EARTH: Standard power cable supplying sockets.

TWO WAY: The arrangement of two switches, which are linked so that either can switch a light on or off.

FLOORING

BITUMEN-EPOXY: A waterproofing, self-leveling floor screed, approximately 2-5mm thick, used as a damp resistant layer for old floors. This will require a latex screed before the finishing layer is applied.

CUSHION FLOOR: A vinyl floor finish with integral foam.

FELT UNDERLAY: Traditional Axminster and Wilton style carpets do not tend to have a bonded foam underlay and the traditional way to smooth out base floor irregularities was to use a felt. This has largely been superceded by rubber foam although felt often has better sound absorption qualities. Felt will need paper as a first layer. Under layers are important and will prevent some wearing.

GRANOLITHIC: See screed. Generally a hard cement / sand layer but only measuring about 15-25mm. This is laid wetter than screed and with strength throughout instead of just on the surface so that it can be used as a wearing surface, particularly in garages.

GRIPPER RODS: Plywood battens around 25mm wide with small nails protruding ‘hedgehog style’. These are laid spike up around the perimeter of a room to grip the edge of a carpet.

LATEX SELF LEVELLING: A mixture of fine aggregate and liquid rubber poured onto a floor to run and find its own level, thereby filling any small holes or slightly off-level areas. Around 6mm is the maximum workable depth.

LINO: A traditional mixture of cork dust or wood dust, flax, chalk and linseed oil which is highly compressed between rollers onto a jute backing and used as flooring. Lino is produced near Dundee in Scotland.

OVER BOARDING: Floorboards are unsuitable for sheet flooring materials, as the joints will show through. This is prevented by over boarding with plywood or with pre-soaked or oiled hardboard. Pre-soaking with water is important to prevent expansion ‘bubbling up’ the boarding.

SCREED: A coarse, washed sand, sometimes granite based and referred to as ‘grano’, which is mixed with cement when slightly damp and spread over a floor to about 65mm then steel trowelled smooth. The screed may be laid over a concrete floor a day or so after setting and monolithically bonded to the concrete by pouring liquid cement (grout) over as glue.

TERRAZZO: A mixture of white cement and marble chippings/powder, laid wet then ground smooth. This is often seen in shop doorways but can also be used for work surfaces and basins.

THERMOPLASTIC: A finishing floor tile of hard vinyl plastic that, in the past, was mixed with asbestos fibre. For this reason, 20-year-old marbled plastic tiles should be treated as suspect.

GROUNDWORKS

BACK-DROP: Where underground drain runs have to change level to go lower, it is not possible to increase the slope downwards beyond certain limits as anything other than clear liquid would be left behind. The way to overcome this is to construct a manhole where the drain comes in at the top and the sewage then free falls down a vertical pipe inside the manhole to the new lower level. The advantage to this method is that the manhole is easily accessible for rodding out blockages. The manhole is called the backdrop.

BENCHING: The channel at the bottom of the manhole is finished with smoothed mortar render to form a self-cleaning slope. This is called benching. Sometimes the benching may break up causing drain to block.

BIT-MAC: Bitumen macadam coated aggregate, which is laid hot for road and drive surfaces. It is generally laid as a two-layer make up with the base course using 20-38mm stone and the wearing course 5-12mm of stone. Dense bitmac (dbm) refers to graded stone where fine stone is mixed in to fill the gaps and add strength. This is generally used for roads or heavily trafficked drives.

BLINDING: Sand topping approximately 30-50mm laid on the surface of the sub-base to prevent the toppings from running into the sub-base. The blinding also allows the toppings to move independently from the sub-base.

BRUSHED CONCRETE: Concrete surface that has been smoothed then finished with a lightly dragged broom to provide grip. This is often seen on petrol garage forecourts.

DPM: Damp proof membrane, used immediately below the concrete ground floor slab to prevent rising damp. This is also sometimes used on top of the blinding on concrete drives as a slip membrane to ensure no binding between the layers.

FORMATION: The deepest point in an excavation for a drive or patio, which is leveled and smoothed prior to laying the sub-base.

HEPSLEVE: A trade name for very hard clay pipes jointed with plastic collars.

PLASTIC: Plastic pipes are often used in domestic underground drainage, as the pipe lengths are light and long compared to clay. The disadvantage is that the pipes are not as strong and may have to be encased in concrete in certain conditions, negating any flexible qualities. In such circumstances, clay may be a better choice.

SALT-GLAZED: Before the super baked clay drainage pipe used today was developed, clay pipes had to be coated in a kiln-fired clear glaze to ensure a watertight smooth surface. These pipes were jointed rigidly with sand/cement and tarred hemp.

SPOIL: Material dug out from an excavation, which may be referred to on site as muck and muck-away for removing from site.

SUB-BASE: The coarse filling such as hardcore or crushed rock that forms a frost resistant strong base to spread and cushion the loads. This is usually at least 100mm thick.

TAMPED CONCRETE: Concrete surface compaction with long heavy board leaving shallow ridges. The ridges should be shallow to allow water to drain.

HEATING / AIRCONDITIONING

BALANCED FLUE: A horizontal gas flue that has concentric tubes, i.e. one inside the other, arranged in this way so that one tube carries out the exhaust fumes and the other brings in the air for combustion. The combustion chamber is thus room-sealed and safe.

BTU: British Thermal Units. A measurement of heat output now replaced by kW. 1 Btu / Hr = 0.000293kW. A 90,000BTu boiler is approximately 26kW.

CONDENSER: The outside unit in an air-conditioning system that disperses the waste heat and condenses the gas back to a liquid.

COPEX: A trade name for flue liners made from flexibly jointed stainless steel. This is used to line brick flues to prevent carbon monoxide leaking into the house.

GRAVITY FED: A central heating system that does not use pumps but circulates the water by gravity and water expansion.

INDIRECT: See indirect tank under Plumber.

KW Kilowatts: A measurement of power, which may be expressed as energy, consumed in a period such as kW/hrs.

LEIGONELLA: The term given to a group of bacteria that thrives in water of between 15 and 450C. The bacteria can infect susceptible people and result in an illness similar to pneumonia. The bacteria has been found in shower heads and it is therefore a good idea to have the domestic water supplies from storage systems regularly flushed professionally if there are persons using systems who are elderly or with health problems. The systems particularly prone are older mixers where the hot and cold are mixed remote from the head.

PRESSURED SYSTEM: A hot water and radiator system that has a sealed pressure vessel to deal with expansion and a safety valve to prevent damage. The advantage is that higher temperatures can be reached, a header tank does not limit the height of radiators and the system can be compact for flats. The system does need special approval from the local council building control.

SPLIT SYSTEM: A term used to describe comfort cooling, commonly termed “air-conditioning”, where the room evaporator and the outside condenser are split and not within a combined unit.

TRV’S: Thermostatic radiator valve. A room temperature sensing valve on a radiator, which locally switches off the radiator at a preset temperature.

PLASTERING

ANGLE BEAD: A thin metal angle designed to reinforce plaster edges at external angles.

BLOWN: Plaster that has lost the bonding key and lifted. This sounds hollow to tapping.

BONDING: A lightweight plaster containing exfoliated vermiculite (a mineral used as a bonding material) as an aggregate used in two-coat plastering, to adhere to smooth surfaces or to make good uneven surfaces. It has some insulation properties.

BROWNING: A gypsum plaster mixed with sand, site or premixed, and used as an undercoat. This is rarely used nowadays as it is quite heavy to spread compared with the lightweight bonding plasters.

CARLITE: A trade name for bonding plaster.

CERIPITE: A trade name for finishing plaster, usually pink in colour.

DUPLEX BOARD: Plasterboard that has a vapour barrier of aluminum foil on one side. This is used for ceilings, and sometimes walls, where it is important to prevent air-bourne moisture passing through and condensing.

FEATHER EDGE: Plasterboard that has tapered edges to allow a jointing plaster and tape to cover the joint. These are smoothed off so that the joints do not show. The decoration can then be applied without the need for finishing plaster.

RENDER: The base coat of plaster or the sand cement coating, which is applied externally.

SCREED: A dryish mixture of coarse, washed sand laid to a depth of 50-75mm over concrete flooring to provide a smooth, steel trowelled surface for a floor finish. The screed has low load resistance and is easily damaged, so must be protected prior to the covering being fitted.

SCRIM: A reinforcing mesh tape, previously made from jute and since replaced with plastics.

SET: Thin finishing coat of plasterwork.

SKIM: A thin coat of plaster applied as finishing over base render or direct to boards.

TAPED JOINT: Feather-edge boards that have the joints filled and covered for direct decoration to avoid plastering.

PLUMBING

ANTI-VACUUM: A one-way valve, which allows air into a drainage system, found by a basin or at the top of an internal soil pipe to balance pressures and prevent the water in U-bends being sucked out.

AIR-LOCK: A bubble of air that gets to the top section of piping and cannot be pushed out by the pipe contents and reduces the flow of the content of the pipe.

BACK-SIPHON: Sometimes if a plug of water is traveling down a drain, it will act as a piston and lower the pressure behind it, pulling out the water in U-bends. This is known as a back-siphon.

BASIN: An item of the sanitary ware in bathrooms fed by a cistern – a closed-lid tank located in the roof space.

CISTERN: The open vessel with removable lid within which the inlet of new water is controlled by a ball float valve. Cisterns exist to maintain a back-up water supply for toilets in the event of water failure and to prevent back siphonage into the fresh water mains.

COMPRESSION: A copper or stainless steel pipe joint fitting that forms a seal by internally crushing a soft copper ring onto the pipe. Easy to fit and remove, but more expensive, unsightly and bulky than a soldered joint.

COPPER: The material used for hot and cold water pipes, generally 15mm to basins and mains fed taps and 22mm to baths.

DOWN PIPE: The soil pipe that rises vertically through a house from the drainage connecting toilets, baths and basins.

HEADER: The small open cistern, usually referred to as a tank, that feeds the radiator water in central heating.

INDIRECT TANK: This is the hot water cylinder where the water for basins and baths is heated by a coil of piping inside the cylinder or tank. The coil of piping is connected to the central heating system and acts as a radiator.

P TRAP: The toilet waste outlet, which passes horizontally into the drainage system.

PRESSURE SYSTEM: A water heating system for hot water to baths and basins which is sealed. Instead of the vent found in a header tank, a pressure vessel controls pressure. The advantage is that the pressure is high and so good for showers. Current Building Regulations require that if fitting this system, the details are submitted as a formal application for approval.

RISER: A vertical water pipe carrying the mains water supply.

S TRAP: The toilet waste outlet that passes vertically downwards into the drainage system.

SINK: The sanitary ware in a kitchen fed by the mains cold supply direct.

U BEND: A U-shaped pipe system, which maintains a residual amount of the waste water to prevent, smells from the drains coming back into the house.

UPVC: Unplasticised polyvinyl chloride, now increasingly avoided due to environmental restrictions, but still in use for drainage pipes and window frames.

ROOFING

ASPHALT: A mixture of bitumen and fine minerals such as clay which is hot-trowelled onto roofs. The melting point is higher than tar so it has higher weather resistance. Asphalt occurs naturally in Trinidad bubbling up in lakes ready mixed with sand, but over extraction has depleted this resource.

BARGE BOARD: The boards fixed against the roof covering on a gable roof.

BATTEN: Treated soft wood, measuring around 25x38mm, which is laid horizontally on top of the sarking felt to hook the tiles / slates on to.

BONNETS: The rounded quadrant shaped tile, which is laid over the hip.

BUILT-UP FELT: Used on flat roofs to provide weathering and so-called as it is laid in two or three layers. The felts may be standard bitumen based or high performance polymer based – the latter has good flexibility properties. Felts are laid in hot bitumen or have the bitumen factory-applied to be melted on-site with a flame torch.

EAVES: The area under the overhanging part of a roof.

FLASHING: A metal sheet cut into brickwork and then dressed over a surface below, used to deflect water from a joint between two adjacent materials, such as brickwork and tiles.

FLAUNCHING: The sand / cement fillet around a chimney pot.

GABLE: The vertical end of a building with a pitched roof where the end wall goes up to form a triangle.

HIP: On a roof which has slopes on all surfaces, i.e. like a pyramid, the long sloping ridge is called the hip and inside, the rafter is the hip rafter.

INTERLOCKING: Usually constructed from coloured concrete, interlocking tiles have interlocking edges and hooked tops. The interlocking sides provide weather resistance without the great overlap of plain tiles, so the weight over an area is lower. However, the tiles are considerably heavier than slates, therefore it is very important to check that the roof structure is strong enough to bear the weight. Interlocking tiles are much cheaper than plain tiles and are a favourite on lower cost houses as a replacement for slates. When looking for new property, be suspicious of older houses that have new interlocking tiles, especially if similar houses in the area have slates. Visible raised areas of tiles on the roof, at the point where two homes join, are a sure sign of overloading of the roof structure. Interlocking tiles work well at low pitch angles and in exposed areas.

NAIL SICKNESS: Copper nails used to fix slates will corrode in time, particularly with the effects of acid rain in city areas. The result is slipping slates.

PEGGED CLAYS: Clay plain tiles that have wooden pegs to hook over the battens instead of the hook formed in tile material. These tiles are found on older buildings and are expensive to replace.

PITCH / PITCHED: The angle of a roof where two slopes meet the ridge. This is referred to as a pitched roof but often incorrectly labeled an ‘apex roof’.

PLAIN CLAYS: The traditional tile is termed flat but has a slight round to spot water creeping up between courses. The size is generally 265x165x10mm thick and the tiling will be three thick at the maximum overlap. This provides the best resistance to wind driven rain but makes the covering heavy compared to slate or interlocking tiles.

PLAIN CONCRETES: Similar in colour and size to plain clay tiles, but at lower cost.

REDLAND 45’S: A common interlocking tile made in concrete with two indent lines and flexible ridges.

SARKING: This is the waterproof felt lain immediately under the roof tile battens to keep out wind driven snow and dust. This also acts as a second waterproof layer.

SOFFIT: The under-surface of any part of a building such as the arch, eaves or cantilevered section.

TINGLES: When faced with slipping slates through nail sickness, there is no easy solution as the slate above prevents access to the damaged nails. In such a situation, it is possible to insert strips of zinc or copper, bent into long ‘S’ shaped hooks, to catch the bottom of the slipped slate. This can then be hooked over the top of the slate above from underneath. These ‘S’ shaped hooks are known as tingles.

UNDER CLOAK: Where tiles or slates overhang the gable bargeboard, the underside is bedded in mortar and finished with special tiles, slates or a inert board, called the undercloaking.

VALLEY: Where two sloping roofs meet, as with two mountains, the valley is the line between.