Burnley College Plastering Diploma Level 2
Internal solid plastering
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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.
Burnley College Plastering Diploma Level 2
History of plastering
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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
Burnley College Plastering Diploma Level 2
Examples of some tools and equipment used for
internal plastering
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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
Burnley College Plastering Diploma Level 2
Preparation of background
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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
Burnley College Plastering Diploma Level 2
Surface key is it good ,
Preparation
moderate or poor
required prior to
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
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).
Burnley College Plastering Diploma Level 2
Types of background in British Standard 5262
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Dense, strong and smooth materials
Moderately strong, porous materials
Moderately weak, porous materials
No fines concrete
Composite backgrounds
Burnley College Plastering Diploma Level 2
Forming a key
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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
Burnley College Plastering Diploma Level 2
Preparation checklist
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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.
Burnley College Plastering Diploma Level 2
What is contained in a specification?
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Type of material
Number of coats
Thickness of plaster
Standard of work
Burnley College Plastering Diploma Level 2
Materials used in plastering
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Sand
Lime
Cement
Plaster
Burnley College Plastering Diploma Level 2
Sand
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Types and sources
of sand
What is meant by a
well-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
Sand contained in a sand bay with protective covering sheet
plastering sand?
Burnley College Plastering Diploma Level 2
Faults with poor quality sand
Symptom
Result
Possible causes
Delayed set or total failure
Weakness, shrinkage,
cracking, delayed expansion
Too 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
Burnley College Plastering Diploma Level 2
Lime
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Manufacture of lime
Types of lime
Hydrated lime
Hydraulic lime
Purpose of lime in a
plastering mix
A lime works
Burnley College Plastering Diploma Level 2
Ordinary Portland cement
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Raw materials of OPC
Manufacture of cement
Hardening and curing of cement
Other types of cement
Lightweight cement-based materials
Burnley College Plastering Diploma Level 2
Plaster
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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
Burnley College Plastering Diploma Level 2
Additives
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Expanded Perlite
Vermiculite
Coloured pigments
Plasticiser
Waterproofers
Hardeners
Burnley College Plastering Diploma Level 2
Proportioning and gauging plastering materials
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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.
Burnley College Plastering Diploma Level 2
Plaster coats – method of work
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One-coat work
Two-coat work
Three-coat work
Dubbing-out coat
Render coat
Application of lightweight plaster
Burnley College Plastering Diploma Level 2
Forming box or broad screed
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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
Burnley College Plastering Diploma Level 2
Dot and screed or plumb and dot
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Use of the dot and screed or plumb and
dot system
Method of forming dot and screed and
plumb and dot systems
Ruling in from
horizontal
screeds
Use of a plumb bob and gauge
Plaster dot
Plumbing in
horizontal
screeds
Burnley College Plastering Diploma Level 2
Setting coat
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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
Burnley College Plastering Diploma Level 2
Setting coat to a plasterboard ceiling:
applying reinforcement
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Types of reinforcement of
plasterboard joints
Application of
reinforcement
Position of reinforcement to a ceiling
Burnley College Plastering Diploma Level 2
Plastering a ceiling or wall on plasterboard in
one coat system
Applying a
finishing coat
to a ceiling
Applying a finishing coat to a partition
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1st coat lay between reinforcement
2nd coat laid over whole ceiling
Always work leaving behind finished work
Trowel up leaving a finished matt surface
Burnley College Plastering Diploma Level 2
Beads (metal and plastic trims)
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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
Burnley College Plastering Diploma Level 2
Forming window openings, reveals and
attached piers
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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
Burnley College Plastering Diploma Level 2
Forming attached piers (1)
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What is an attached pier?
Back wall floated flat and keyed
Looking down onto an attached pier
An attached pier
Burnley College Plastering Diploma Level 2
Attached and independent piers (2)
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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
Burnley College Plastering Diploma Level 2
Lining in attached piers
Method of lining in face of pier
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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
Burnley College Plastering Diploma Level 2
Independent piers
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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
Burnley College Plastering Diploma Level 2
Floating and setting coat to a ceiling
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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 ceiling
Setting out of dots to a ceiling
Burnley College Plastering Diploma Level 2
Floating a beam
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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
Burnley College Plastering Diploma Level 2
Method of patching a ceiling
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Method of forming repairs to a wood lath ceiling
Method of forming repairs to a plasterboard ceiling
Burnley College Plastering Diploma Level 2
Making good to a wall
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Brush down damaged area; remove dust.
Rake out mortar joints to form key.
Remove plaster to form undercut under existing plaster.
Wet in background area and undercut, or coat with PVA adhesive.
When PVA is tacky, add plastering material to repair.
Rule in floating coat, then key to receive finishing coat.
When plaster set, cut back floating – especially around edges of repair.
Wet in surrounding area and add finishing coat.