Burnley College Level 2 Plastering
Dry lining by direct bond – overview
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In recent years, dry lining has developed more
than any other form of plastering.
Most new buildings, especially houses,
contain some form of dry lining.
Direct bond is a dry method of producing
a flat wall surface.
Sheets of plasterboard are secured to the background surface,
leaving air space between the board and background.
Because it’s a better insulator than solid plaster, it will result in a
warmer house.
Construction is speedy and it dries out quickly, which means
decoration can take place sooner.
Quick construction = quick financial return for house builders.
Burnley College Level 2 Plastering
Tools for installing direct bond system
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Hawk and trowel for
applying adhesive dabs
Tape measure
Pad saw
Chalk line
Spirit level
Square for fixing returns
Straight edge
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Foot lifter
Broad saw
Internal corner trowel
Taping
Applicator
Hand sander and universal sander
Jointing sponge
Burnley College Level 2 Plastering
Equipment for installing direct bond system
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Hand-held electric mixer (110 volts) – for mixing adhesives
Whisk or paddle – for use with electric mixer
Plastic mixing drum – for mixing smaller quantities of adhesives
Different sizes of buckets or containers for different quantities of adhesives
Spot board and stand
Cement pan for keeping jointing material in – used with the taping knife
Access equipment if required
Burnley College Level 2 Plastering
Materials
Types of board
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Tapered-edged plasterboard
9.5 or 12.5 mm thickness
900 or 1200 mm width
Tapered-edge plasterboard is thinner at the edges than the rest of board
Burnley College Level 2 Plastering
Jointing materials
Jointing materials
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Setting materials
Air-drying material
Part setting + part air-drying
Mixing of jointing materials
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Some materials are in powder form.
Some materials come pre-mixed.
Powder materials should be mixed to a smooth paste with no lumps or
hard particles.
Burnley College Level 2 Plastering
Joint reinforcement
Reinforcement is needed to help prevent the joints between the boards from
moving and cracking. This comes in the following forms:
• paper joint tape
• self-adhesive glass fibre mesh
• reinforced corner tape
• drywall metal beads
• drywall plastic beads.
Note: glass fibre tape is not recommended by manufacturers.
Burnley College Level 2 Plastering
Background
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Preparation of background
Quality of background and how will it affect the method of direct bond
Thickness of ‘dabs’
What is a ‘tacker or boarder’?
When is a building ready for dry lining?
What should happen to services before dry lining?
Burnley College Level 2 Plastering
Setting out a plain wall
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Find the high spot of wall.
Transfer high spot to ceiling.
Method of transferring
high spot to ceiling
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Add 10 mm on high spot for thickness of dab.
Snap chalk lines.
Transfer lines down to floor.
Set out boards from internal angle
Set out end of boards and centre of boards
Setting out plasterboard for direct bond
Burnley College Level 2 Plastering
Attached piers
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Face of attached pier should run
parallel with back wall when pier is
in the centre of a wall.
An attached internal angle pier is
within the corner of a room.
Attached piers should be plumb and
square.
Squaring in an attached pier
Burnley College Level 2 Plastering
Window opening
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Set out window wall as for a plain wall.
Set out boards from a window reveal towards the internal angle.
Board at window external angle should overhang to allow for a neat angle
when the window reveal board is bedded on.
Gap under window may not be same size as a full plasterboard sheet so
will need to be trimmed accordingly.
A continuous strip of adhesive is placed on the background at curtain rail
height.
Burnley College Level 2 Plastering
Fixing plasterboard
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Cut board to height and fix one board at a time.
Apply continuous strip of adhesive around perimeter of the wall, services
and openings.
Apply adhesive dabs 250 mm long, 50-75 mm wide and no nearer than
25 mm to board edge lines.
Offer grey side of plasterboard to dabs and lift up to ceiling with foot lifter.
Tap boards back to dabs to line up with chalk lines.
Wedge board in place.
Repeat making sure edge of board is lightly butted against the last board.
Run a straight edge across face horizontally and diagonally to check
for flatness.
Burnley College Level 2 Plastering
Separating walls
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Add a parge coat to the background before applying direct bond to help
with sound insulation. It is applied at 6 mm thickness and not scratched.
For insulating boards a special type of nail called a ‘nailable plug’ is fixed
through the dab when the adhesive dab has set. This will prevent
insulation board from falling off the wall if in a fire.
Burnley College Level 2 Plastering
Hand taping and jointing
The suggested order for applying joints is:
1. internal angles
2. tapered-edged joints
3. cut board edge joints
4. external angles.
Method of forming joints
• Cut tapes.
• Apply band of jointing material into depression.
• Press tape into filler.
• Cover tape with joint filler flush with board.
• Feather out jointing material with sponge.
• Apply a further two coats after each coat has dried and feather out with sponge.
• When first learning to tape slightly damp plasterboard either side of joint
Burnley College Level 2 Plastering
Methods of forming external angles
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Apply adhesive 50 mm each side of joint.
Bend tape to 90°.
Use thumb and forefinger to press tape into adhesive.
Slight pinch action is used to raise nosing
of tape.
Finish off as for taping straight joints.
Burnley College Level 2 Plastering
Sealing the boards
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All joints should be lightly sanded down.
Remove dust.
Apply sealer by brush or roller.
Why should the boards be sealed?
Burnley College Level 2 Plastering
Name three tools used for fixing
plasterboard for direct bond.?
Hawk and trowel for
applying adhesive dabs
Tape measure
Pad saw
Chalk line
Spirit level
Square for fixing returns
Straight edge
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Foot lifter
Broad saw
Internal corner trowel
Taping
Applicator
Hand sander and
universal sander
• Jointing sponge
Burnley College Level 2 Plastering
List two thicknesses and widths of
plasterboard used in direct bond
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thickness: 9.5 mm and 12.5 mm, width: 900 mm and 1200 mm
Burnley College Level 2 Plastering
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What type of plasterboard is best for direct bond?
The best type of plasterboard for direct bond is tapered-edged plasterboard
Burnley College Level 2 Plastering
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Name two different types of jointing material.
setting material, air-dry material
Burnley College Level 2 Plastering
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To produce the best results with jointing material what should you avoid within the
material?
Jointing material should be mixed to a smooth paste with no lumps or set
hard pieces of jointing material.
Burnley College Level 2 Plastering
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Name two types of reinforcement used on plasterboard joints in direct bond.
two types of joint tape: paper tape and self-adhesive glass fibre mesh
Burnley College Level 2 Plastering
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Name two types of reinforcement used on external angles in direct bond.
reinforced paper corner tape, drywall metal beads
Burnley College Level 2 Plastering
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The background for direct bond should be of what quality and why?
The background for direct bond should be of good quality and level, because
if the adhesive used to fix the boards is too thick it will not hold the boards
securely back to the background.
Burnley College Level 2 Plastering
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Dabs of bonding adhesive for fixing plasterboard should be no thicker than:
a
10 mm
b
15 mm
c
20 mm
d
25 mm
Burnley College Level 2 Plastering
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What should happen with electrical wires and pipes that are larger than the air gap
behind the plasterboard?
Pipes and electrical cables should be chased into the background if possible
Burnley College Level 2 Plastering
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What is the first thing that should be done when setting out for direct bond?
The first thing to do when setting out for direct bond is find the high spot
Burnley College Level 2 Plastering
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After marking the width of the plasterboard from the internal angles what should be
done next?
After marking the width of plasterboard, mark the centre of the
plasterboards.
Burnley College Level 2 Plastering
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When dry lining a window wall, where should you start the setting out?
The setting out of a window wall should start from the external angles of the
window
Burnley College Level 2 Plastering
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What should be the length of the adhesive dabs?
The length of a dab should be the length of the trowel – about 250 mm.
Burnley College Level 2 Plastering
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Where on a plain flat wall should a continuous strip of adhesive be placed?
A continuous strip of adhesive should be placed around the perimeter of the
wall and around electrical power sockets and light switches
Burnley College Level 2 Plastering
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How many strips of vertical adhesive are required to secure a sheet of
plasterboard for direct bond?
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2
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3
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4
d
5
Burnley College Level 2 Plastering
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What is the purpose of a ‘parge coat’ on a separating wall?
The parge coat acts as a sound barrier between separating walls.
Burnley College Level 2 Plastering
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When using an insulating board, what is used, besides the dabs, to secure the
board?
a nailable plug
Burnley College Level 2 Plastering
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What is the head of a window called?
The head of a window is the soffit or top of the window.
Burnley College Level 2 Plastering
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Name three tools used in hand taping.
Any three of the following: trowel, filling knife, sponge,
internal angle trowel
Burnley College Level 2 Plastering
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Why is plasterboard sealed before decoration?
Plasterboard is sealed before decoration because of the different suctions
between the jointing material and the plasterboard face. If the boards are not
sealed the joints will show through.
Burnley College Level 2 Plastering
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What should be done to the joints after completion but before sealing?
Before sealing and after finishing of joints they should be lightly sanded.
Burnley College Level 2 Plastering
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When using a paper reinforcing tape for angles how is the nosing of the tape
raised?
The external reinforced paper tape is raised by running the thumb and
forefinger in a slight pinching action down the tape which will raise
the nosing.
Burnley College Level 2 Plastering
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For an exposed angle what type of reinforcement is best?
For exposed external angles an external metal dry lining bead is best.
Burnley College Level 2 Plastering
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What should be done if a blister is found in the paper joint?
If a blister is found it should be cut out and a new tape applied.