Burnley College Plastering Diploma Level 2 Internal solid plastering Internal plastering covers...

Burnley College Plastering Diploma Level 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.


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


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 Two sizes of plastering trowel


Preparation of background

• What is adhesion?

• What is suction and how does it improve or hinder a plasterer?

Block work toothed into facing brickwork


Types of background

1.Normal clay bricks or blocks

2.Dense clay brickwork, blockwork, calcium silicate blocks, concrete blocks

3.Dense concrete, engineering bricks

4.Painted brickwork, glazed tiles, glazed brickwork

Surface key is it good , moderate or poor

Good key:• if joints are raked out• keyed blocks• when keyed bricks are

usedModerate 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 in British Standard 5262

• Dense, strong and smooth materials

• Moderately strong, porous materials

• Moderately weak, porous materials

• No fines concrete

• Composite backgrounds


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


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.


What is contained in a specification?

• Type of material

• Number of coats

• Thickness of plaster

• Standard of work


Materials used in plastering

• Sand

• Lime

• Cement

• Plaster


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


Symptom Result Possible causesDelayed set or total failure Weakness, shrinkage,

cracking, delayed expansionToo much clay

Very slow set of gauged lime mortar

Delay in build Too much clay, animal or vegetable matter (e.g. leaves)

Low finished strength or mortar Poor sticking of backing coats Too much sand; too much clay

Efflorescence, dampness and rusting of metalwork

Unsightly appearance, damage to brickwork

Too much salt

Poor workability Poor stickability Badly graded sand

Rust-coloured staining Lots of expansion Too much iron impurity

Blowing of plasters and rendering

Bond failure Clay balls or coal particles

Faults with poor quality sand


Lime

• Manufacture of lime

• Types of lime

• Hydrated lime

• Hydraulic lime

• Purpose of lime in a plastering mix

A lime works


Ordinary Portland cement

• Raw materials of OPC

• Manufacture of cement

• Hardening and curing of cement

• Other types of cement

• Lightweight cement-based materials


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


Additives

• Expanded Perlite

• Vermiculite

• Coloured pigments

• Plasticiser

• Waterproofers

• Hardeners


Proportioning and gauging plastering materials

• Method of gauging materials

• Traditional cement, lime, sand mixes

• Mixing in a trough

• Mixing in a bucket or drum

• Mixing by cement mixer

• Mixing by hand

Mixing of lightweight plaster in a trough, using a larry/rake. Work station set up.


Plaster coats – method of work

• One-coat work

• Two-coat work

• Three-coat work

• Dubbing-out coat

• Render coat

Application of lightweight plaster


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

Ruling in a vertical screed


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

Use of a plumb bob and gauge

Plumbing in horizontal screeds

Ruling in from horizontal screeds

Plaster dot


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

A bucket of mixed finishing plaster


Setting coat to a plasterboard ceiling: applying reinforcement

• Types of reinforcement of plasterboard joints

• Application of reinforcement

Position of reinforcement to a ceiling


Plastering a ceiling or wall on plasterboard in one coat system

Applying a finishing coat to a partition

Applying a finishing coat to a ceiling

• 1st coat lay between reinforcement• 2nd coat laid over whole ceiling• Always work leaving behind finished work• Trowel up leaving a finished matt surface


Beads (metal and plastic trims)

• Purpose of beads

• Types of beads available

• Method of fixing of angle beads

• Standards required for the fixing of beads

Fixing and levelling in an angle bead


Forming window openings, reveals and attached piers

• Method of fixing beads around windows

• Using timber rules around window openings

• Forming reveals to window openings using reveal gauge

• Forming returns and corners to attached piers


Forming attached piers (1)

• What is an attached pier?• Back wall floated flat and keyed

An attached pier

Looking down onto an attached pier


Attached and independent piers (2)

• Fix angle beads or timber rules plumb and straight

• Check at top, middle, bottom, for equal measurement on face

• When using angle beads check for squareness at top, middle and bottom

• Float and set face and returns when using beads

• When using rules float face, return rules onto face. Float and set returns

• Return rules back onto return and set face


Lining in attached piers

Method of lining in face of pier

• Angle beads fixed at the two ends

• String through line• Place a nail or piece of timber

between string and nosing of two end angle beads

• Fix intermediate angle beads checking for plumb and straightness

• Check that nosing of bead does not fail on the string

Lining through a row of attached piers


Independent piers

• Lay floating rule on floor thickness of floating from face of pier

• Mark along rule with a pencil• Using building square against

rule mark floor• Continue around pier• Place nosing of bead on

intersection of lines

Setting out and squaring in an independent pier


Floating and setting coat to a ceiling

• Set up a datum line• Position of dots on ceiling by

using the building square• Positioning and ruling in

screeds using dots on ceiling• Float up ceiling off of screeds• Form a finishing coat

to ceilingSetting out of dots to a ceiling


Floating a beam

• Fix and line through beads

• Check squareness of side checks of beam

• Check measurement of soffit of beam

• Position of screeds and ruling in

• Method of finishing beam

Worm’s eye view of a ceiling beam


Method of patching a ceiling

• Method of forming repairs to a wood lath ceiling

• Method of forming repairs to a plasterboard ceiling


Making 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.

Burnley College Plastering Diploma Level 2 Internal solid plastering Internal plastering covers...

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