Presentation on theme: "Internal solid plastering"— Presentation transcript:
1Internal solid plastering Internal plastering covers walls and ceilings, prior to decoration.A variety of materials can be used to provide a sound, flat, smooth surface for decoration.Sometimes, decoration is needed.Plastering provides sound and thermal insulation.It also improves levels of hygiene, allowing for wiping down.
2History of plastering Plaster is at least 4,000 years old. It was used by the Egyptians (in the pyramids) and the Greeks (who produced plasterwork in 500 BC).The Romans introduced plastering to England.Henry III admired the whiteness and fineness of gypsum (‘Plaster of Paris’), so he brought it to England.Plasterers were formed into a guild (a company) which was granted a charter by Henry VII.Decorative ceiling and frieze
3Examples of some tools and equipment used for internal plastering HawkTrowelFloatsSpirit levelGauging trowelSpot board and standFloating rulesMixing equipmentInternal angle trowelsOther tools and equipment requiredTwo sizes of plastering trowel
4Preparation of background What is adhesion?What is suction and how does it improve or hinder a plasterer?Block work toothed into facing brickwork
5Surface key is it good , moderate or poor Good key:if joints are raked outkeyed blockswhen keyed bricks are usedModerate key:flush brickwork or blockworkPoor key:unless surface has been keyed in manufacturePreparation required prior to plasteringBrush and damp down according to suction.Rake out soft joints in old brickwork.Test suction if poor and apply spatterdash coat.Mechanical key, hand key or spatterdash coat.Test with bonding agent (PVA).Types of backgroundNormal clay bricks or blocksDense clay brickwork, blockwork, calcium silicate blocks, concrete blocksDense concrete, engineering bricksPainted brickwork, glazed tiles, glazed brickwork
6Types of background in British Standard 5262 Dense, strong and smooth materialsModerately strong, porous materialsModerately weak, porous materialsNo fines concreteComposite backgrounds
7Forming a key Purpose of a key Forming a mechanical key Forming a spatterdash coatUsing liquid PVA or EVA for forming a keyForming a key by hacking the surface
8Preparation checklist Brush down background to clean it.Remove mortar snots from joints, internal and external angles.Make a key (if needed) to background.Test background for suction; treat if necessary.Place drop boards at bottom of wall to catch falling materials and keep floor cleaner.Fix EML to timber wall and soleplates as necessary.Fix angle beads.Set up spot board and stand; wet in the board.
9What is contained in a specification? Type of materialNumber of coatsThickness of plasterStandard of work
10Materials used in plastering SandLimeCementPlaster
11Sand Types and sources of sand What is meant by a well-graded sand? What is the purpose of sand?The effects of bulkingPerforming a simple site test for sandWhat is silt and how does it affect plastering sand?Sand contained in a sand bay with protective covering sheet
12Faults with poor quality sand SymptomResultPossible causesDelayed set or total failureWeakness, shrinkage, cracking, delayed expansionToo much clayVery slow set of gauged lime mortarDelay in buildToo much clay, animal or vegetable matter (e.g. leaves)Low finished strength or mortarPoor sticking of backing coatsToo much sand; too much clayEfflorescence, dampness and rusting of metalworkUnsightly appearance, damage to brickworkToo much saltPoor workabilityPoor stickabilityBadly graded sandRust-coloured stainingLots of expansionToo much iron impurityBlowing of plasters and renderingBond failureClay balls or coal particles
13Lime Manufacture of lime Types of lime Hydrated lime Hydraulic lime Purpose of lime in a plastering mixA lime works
14Ordinary Portland cement Raw materials of OPCManufacture of cementHardening and curing of cementOther types of cementLightweight cement-based materials
15Plaster Chemical formula of plaster CaSO4 2H2O Setting of plaster Types of plaster and their usesStorage of plaster and effects of poorly stored plasterMethod of mixing different types of plaster
17Proportioning and gauging plastering materials Method of gauging materialsTraditional cement, lime, sand mixesMixing in a troughMixing in a bucket or drumMixing by cement mixerMixing by handMixing of lightweight plaster in a trough, using a larry/rake. Work station set up.
18Plaster coats – method of work One-coat workTwo-coat workThree-coat workDubbing-out coatRender coatApplication of lightweight plaster
19Forming box or broad screed The purpose of screedsThe method of forming screeds, horizontally and verticallyMethod of ruling off screedsFilling in between screedsMethod of forming a key between plaster coatsRuling in a vertical screed
20Dot and screed or plumb and dot Use of the dot and screed or plumb and dot systemMethod of forming dot and screed andplumb and dot systemsPlumbing inhorizontal screedsRuling in from horizontal screedsUse of a plumb bob and gaugePlaster dot
21Setting coat Method of forming a finishing coat depends on background Finishing coat should not be stronger than backing coatPurpose of a finishing coatMethod of forming a finishing coat to a floated backgroundThe setting system; trowel, trowel, and trowel, float, trowelA bucket of mixed finishing plaster
22Setting coat to a plasterboard ceiling: applying reinforcement Types of reinforcement of plasterboard jointsApplication of reinforcementPosition of reinforcement to a ceiling
23Plastering a ceiling or wall on plasterboard in one coat system Applying a finishing coat to a ceilingApplying a finishing coat to a partition1st coat lay between reinforcement2nd coat laid over whole ceilingAlways work leaving behind finished workTrowel up leaving a finished matt surface
24Beads (metal and plastic trims) Purpose of beadsTypes of beads availableMethod of fixing of angle beadsStandards required for the fixing of beadsFixing and levelling in an angle bead
25Forming window openings, reveals and attached piers Method of fixing beads around windowsUsing timber rules around window openingsForming reveals to window openings using reveal gaugeForming returns and corners to attached piers
26Forming attached piers (1) What is an attached pier?Back wall floated flat and keyedLooking down onto an attached pierAn attached pier
27Attached and independent piers (2) Fix angle beads or timber rules plumb and straightCheck at top, middle, bottom, for equal measurement on faceWhen using angle beads check for squareness at top, middle and bottomFloat and set face and returns when using beadsWhen using rules float face, return rules onto face. Float and set returnsReturn rules back onto return and set face
28Lining in attached piers Method of lining in face of pierAngle beads fixed at the two endsString through linePlace a nail or piece of timber between string and nosing of two end angle beadsFix intermediate angle beads checking for plumb and straightnessCheck that nosing of bead does not fail on the stringLining through a row of attached piers
29Independent piersLay floating rule on floor thickness of floating from face of pierMark along rule with a pencilUsing building square against rule mark floorContinue around pierPlace nosing of bead on intersection of linesSetting out and squaring in an independent pier
30Floating and setting coat to a ceiling Set up a datum linePosition of dots on ceiling by using the building squarePositioning and ruling in screeds using dots on ceilingFloat up ceiling off of screedsForm a finishing coat to ceilingSetting out of dots to a ceiling
31Floating a beam Fix and line through beads Check squareness of side checks of beamCheck measurement of soffit of beamPosition of screeds and ruling inMethod of finishing beamWorm’s eye view of a ceiling beam
32Method of patching a ceiling Method of forming repairs to a wood lath ceilingMethod of forming repairs to a plasterboard ceiling
33Making good to a wall 1. Brush down damaged area; remove dust. 2. Rake out mortar joints to form key.3. Remove plaster to form undercut under existing plaster.4. Wet in background area and undercut, or coat with PVA adhesive.5. When PVA is tacky, add plastering material to repair.6. Rule in floating coat, then key to receive finishing coat.7. When plaster set, cut back floating – especially around edges of repair.8. Wet in surrounding area and add finishing coat.