Local Flatness Standards

A ruler of 200 mm applied on the cladding of the drywall, particularly at the joints, must not have a difference bigger than 1 mm between the most salient point and the point furthest away.

General Flatness Standards

A ruler of 2000 mm length applied to the face of the drywall and moved in all directions must not have a difference bigger than 4 mm between the most salient point and the point furthest away

Jointing and finishing stages

The jointing of gypsum board goes through stages Q1 and Q2 and finishing from Q3 to Q4.

Shallow light (natural or artificial) can affect the appearance of the surface. Ideally, lighting conditions where the board systems are used should be known in advance. The surface quality should not be judged by flood-lighting, and the limits of manual workmanship should be considered.

• The basic filling of plasterboard joints (Q1) : This is recommended for
  jointing of the internal layer of Gypsum boards for a double layer partition
• Jointing Level 1 includes:
  
  1. Filling the joints between boards
  2. Covering screw heads
• Basic filling includes the taping of the joint
• Excess jointing material should be removed. Tool marks, grooves and ridges are allowed

Jointing level 2 (Q2)

• Jointing Level 2 (Q2) involves Q1 + levelling the joint to the board surface
  with Pro-Fill / Easi-Fill
• Q2 fulfills the basic requirements for walls and ceilings
• The main objective is to provide continuous transition from the joint area to the board surface. The same applies to fixings, corners, and expansion joints
• Jointing Level 2 includes:
  
  1. Basic filling (Q1)
  2. Smooth transition to the board surface, including sanding jointed areas if necessary. Application marks or ridges may not be totally eliminated
• This type of surface is suitable for:
  
  1. Medium and coarse structured wall coverings, e.g. ingrain / textured wallpaper or standard wallpaper
  2. Matt, filling, medium and coarse structured paint coatings/coats (e.g. emulsion paints) that are applied manually with a lambskin or structured roller
  3. Top coats (maximum particle size > 1mm)
• Jointing Level 2 finish does not eliminate physical marks/ridges completely. These effects can be reduced by specifying Jointing Level 3

Finishing Level 3 (Q3)

• Jointing and finishing in accordance with Finishing Level 3 (Q3) includes:
  
  1. Jointing and finishing to Q2
  2. Wider finishing of the joint (400 to 450mm) and a tight coat of
  Pro-Fill / Easi-Fill (< 1mm) to the entire plasterboard surface, filling the pores
• Physical ridges and grooves are not acceptable, except the ones observed
  under shallow light
• The level and extent of such marks is considerably lower than Q2
• This type of drywall surface is suitable for
  
  1. Fine structured wall coverings
  2. Matt and fine structured paint coatings
  3. Top coats (maximum particle size less than 1 mm)

Finishing level 4 (Q4)

• High-end drywall surface where the entire drywall is covered with a layer of
  jointing material or a skimming plaster (thickness > 1mm)
• The skim coat minimises any marks or traces on the drywall surface and in the joints.
  Skimmed surfaces that are perfectly even and free of shading are impossible to achieve
• Quality Level 4 includes:
  
  1. Jointing and finishing to Q2
  2. Covering the surface completely with Gyproc Champion Skimming Putty
  (thickness > 1mm)
• The undesirable effects of shallow lighting are considerably reduced. Some visible imperfections in natural lighting may be acceptable because of the limits of manual workmanship
• Depending on the site, it is recommended to try out or test the Q4 surface on an area of sufficient size under final lighting conditions. This job will normally be ordered separately by the client
• This type of drywall surface is suitable for:
  
  1. Smooth or structured glossy wall coverings, such as metal-based or vinyl wallpapers
  2. Paints or coats up to medium gloss
• Special coatings, stucco marble or similar specialist decorative finishes
• In specific cases (glossy/ varnish/ wallpapers with varnish) it may be necessary to
  introduce additional procedures for the pre-treatment of the final drywall surface

Performance Benefits of Q4 levels of Finish

A Q4 finish delivers far superior aesthetics. This level of finish also offers significant performance benefits in acoustics and fire safety.

Effect on Acoustical Performance

Cracks affect acoustics or isolation of a drywall by "flanking" the sound. Sound can flank over, under, or around a wall or through air gaps. Noise passes through spaces at the weakest points. This air-gap, or "flanking" path, can seriously degrade the isolation quality of a wall.

• A tiny crack/gap of a width of 0.1mm can reduce the overall insulation performance of a drywall by 15%
• A crack/gap of a width of up to 0.5mm can reduce the performance by approximately 35%
• A crack/gap of 1mm will give a dismal performance of 50%

Effect on Fire Performance

A fire-resistant system acts as a shield against fire, heat, smoke and harmful gases. Cracks or gaps reduce the fire-resistance of a drywall. Smoke and gases can easily pass through such cracks or gaps and cause discomfort and health hazards.

A Q4 level of finish not only improves the look and feel of the interiors, it also delivers superb acoustic and fire safety performance.