1. Dry lining by direct bond – overview
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.

2. Tools for installing direct bond system
Hawk and trowel for applying adhesive dabs
Tape measure
Pad saw
Chalk line
Spirit level
Square for fixing returns
Straight edge
Foot lifter
Broad saw
Internal corner trowel
Taping
Applicator
Hand sander and universal sander
Jointing sponge

3. Equipment for installing direct bond system
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

4. Materials Types of board 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

5. Jointing materials Jointing materials Mixing of jointing materials
Setting materials
Air-drying material
Part setting + part air-drying
Mixing of jointing materials
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.

6. 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.

7. Background 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?

8. Setting out a plain wall
Find the high spot of wall.
Transfer high spot to ceiling.
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
Method of transferring high spot to ceiling
Setting out plasterboard for direct bond

9. Attached piers
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

10. Window opening 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.

11. Fixing plasterboard 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, 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.

12. Separating walls
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.

13. 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

14. Methods of forming external angles
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.

15. Sealing the boards All joints should be lightly sanded down.
Remove dust.
Apply sealer by brush or roller.
Why should the boards be sealed?

16. Name three tools used for fixing plasterboard for direct bond.?
Foot lifter
Broad saw
Internal corner trowel
Taping
Applicator
Hand sander and universal sander
Jointing sponge
Hawk and trowel for applying adhesive dabs
Tape measure
Pad saw
Chalk line
Spirit level
Square for fixing returns
Straight edge

17. List two thicknesses and widths of plasterboard used in direct bond.
thickness: 9.5 mm and 12.5 mm, width: 900 mm and 1200 mm

18. What type of plasterboard is best for direct bond?
The best type of plasterboard for direct bond is tapered-edged plasterboard

19. Name two different types of jointing material.
setting material, air-dry material

20. 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.

21. 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

22. Name two types of reinforcement used on external angles in direct bond.
reinforced paper corner tape, drywall metal beads

23. 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.

24. Dabs of bonding adhesive for fixing plasterboard should be no thicker than:
a 10 mm
b 15 mm
c 20 mm
d 25 mm

25. 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

26. 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

27. 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.

28. 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

29. What should be the length of the adhesive dabs?
The length of a dab should be the length of the trowel – about 250 mm.

30. 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

31. How many strips of vertical adhesive are required to secure a sheet of plasterboard for direct bond?

32. What is the purpose of a ‘parge coat’ on a separating wall?
The parge coat acts as a sound barrier between separating walls.

33. When using an insulating board, what is used, besides the dabs, to secure the board?
a nailable plug

34. What is the head of a window called?
The head of a window is the soffit or top of the window.

35. Name three tools used in hand taping.
Any three of the following: trowel, filling knife, sponge,
internal angle trowel

36. 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.

37. What should be done to the joints after completion but before sealing?
Before sealing and after finishing of joints they should be lightly sanded.

38. 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.

39. For an exposed angle what type of reinforcement is best?
For exposed external angles an external metal dry lining bead is best.

40. 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.