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Internal solid plastering

Internal solid plastering. Internal 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.

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Internal solid plastering

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  1. Internal solid plastering

  2. Internal 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.

  3. History 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

  4. Examples of some tools and equipment used for internal plastering • Hawk • Trowel • Floats • Spirit level • Gauging trowel • Spot board and stand • Floating rules • Mixing equipment • Internal angle trowels • Other tools and equipment required

  5. Preparation of background • What is adhesion? • What is suction and how does it improve or hinder a plasterer?

  6. Surface key is it good , moderate or poor • Good key: • if joints are raked out • keyed blocks • when keyed bricks are used • Moderate key: • flush brickwork or blockwork • Poor key: • flush brickwork or blockwork • unless surface has been keyed in manufacture • Preparation required prior to plastering • Brush 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 background • Normal clay bricks or blocks • Dense clay brickwork, blockwork, calcium silicate blocks, concrete blocks • Dense concrete, engineering bricks • Painted brickwork, glazed tiles, glazed brickwork

  7. Types of background in British Standard 5262 • Dense, strong and smooth materials • Moderately strong, porous materials • Moderately weak, porous materials • No fines concrete • Composite backgrounds

  8. Forming a key • Purpose of a key • Forming a mechanical key • Forming a spatterdash coat • Using liquid PVA or EVA for forming a key • Forming a key by hacking the surface

  9. Preparation 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.

  10. Materials used in plastering • Sand • Lime • Cement • Plaster

  11. Sand • Types and sources of sand • What is meant by awell-graded sand? • What is the purpose of sand? • The effects of bulking • Performing a simple site test for sand • What is silt and how does it affect plastering sand? Sand contained in a sand bay with protective covering sheet

  12. Faults with poor quality sand

  13. Lime • Manufacture of lime • Types of lime • Hydrated lime • Hydraulic lime • Purpose of lime in a plastering mix A lime works

  14. Ordinary Portland cement • Raw materials of OPC • Manufacture of cement • Hardening and curing of cement • Other types of cement • Lightweight cement-based materials

  15. Plaster • Chemical formula of plaster CaSO4 2H2O • Setting of plaster • Types of plaster and their uses • Storage of plaster and effects of poorly stored plaster • Method of mixing different types of plaster

  16. Plaster coats – method of work • One-coat work • Two-coat work • Three-coat work • Dubbing-out coat • Render coat

  17. Forming box or broad screed • The purpose of screeds • The method of forming screeds, horizontally and vertically • Method of ruling off screeds • Filling in between screeds • Method of forming a key between plaster coats

  18. Dot and screed or plumb and dot • Use of the dot and screed or plumb and dot system • Method of forming dot and screed and plumb and dot systems

  19. Setting coat • Method of forming a finishing coat depends on background • Finishing coat should not be stronger than backing coat • Purpose of a finishing coat • Method of forming a finishing coat to a floated background • The setting system; trowel, trowel, and trowel, float, trowel

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