Technical guide · Pandaboard

Gypsum Board Partitions and Ceilings: Spacing, Screws and Joints

Gypsum board is supplied at 1200×2400 or 1200×3000 mm in 9.5, 12, 12.5 and 15 mm, in regular, moisture-resistant, fire-rated and water-repellent types that must not be mixed in one assembly. Partitions use C50 or C75 studs at 400 or 600 mm centers with U floor and ceiling tracks; ceilings use furring channels at 400 mm. Space screws at 150–170 mm, sink heads 0.5–1 mm without breaking the paper, leave 3–5 mm joints, stagger adjacent boards by at least 600 mm, and cut corners and openings from a single board.

Paper-faced gypsum board is the most widely used substrate for interior partitions and ceilings. The board carries no load itself — all strength comes from the framing and the fixing pattern. The same board is used in three different ways for partitions, ceilings and direct fixing; this guide separates them.

01Key specifications and suitability

Suitable

• Party walls in housing and apartments

• Office partitions and corridors

• Hotel guest room walls

• Ceilings, beam and pipe boxing

• Public buildings needing fire compartments

Not suitable

• Shower enclosures and pool interiors

• Outdoor and semi-outdoor walls

• Workshops with strong acids or live steam

• Warehouse partitions hit by forklifts

• Bonding direct to untreated old walls

02Preparation Before Installation

2.1 Materials and tools

Table 2-1 Main materials

Parts list and reference quantities：Per 100 m² of one partition face, studs at 400 mm, 3 m height; includes wastage. Double-sided partitions need twice the board.

2.2 Site conditions

• Main structure accepted; wall verticality and floor flatness within tolerance;

• Services embedded (conduits and switch boxes in partitions already fixed);

• Ambient temperature ≥5 ℃; boards delivered 24 h in advance and stored flat;

• Partition setting-out lines snapped on the floor and matching lines on the soffit.

2.3 Delivery and site conditioning

• Move boards indoors at least 24 h before installation and stack them flat on bearers at ≤600 mm centres so moisture content equalises with the room and shrinkage joints do not open later

• Use one batch and one shade per room or elevation; mixing batches shows as a visible colour difference

• Spot-check 5 % on arrival: flat face, intact edges, no blistering or scratches; reject boards with diagonal deviation over 2 mm

• Cut in a separate area, clear dust immediately and seal cut edges as described in this guide

03System 1: Partition

Figure 1 Light-gauge steel partition Floor and ceiling track + studs + bracing channel; boards staggered on each side, cavity filled with rock wool.

1. Set out - Snap the partition centerline and edges on the floor and soffit, and mark the door and window openings at the same time.

2. Fix floor and ceiling tracks - Fix the U tracks with powder-actuated pins or expansion bolts at ≤600 spacing; fit a sealing strip between track and structure.

3. Install studs - Insert C studs into the tracks at 400 (9.5 board) or 600 (12 board and above); connect to the tracks with blind rivets or screws.

4. Install bracing channels - Where the wall is higher than 3 m, add bracing channels (through channels) to improve stability; keep the openings facing the same way.

5. Reinforce openings - Add studs at both sides of openings and a nogging or reinforced stud above them; never leave the board spanning unsupported.

6. Board one side - Start boarding from one side, stagger the joints, screw spacing 150–170, screws 10–15 from the board edge.

7. Add rock wool - Fill the cavity completely with rock wool at ≥40 kg/m³; do not leave voids (both acoustics and fire performance depend on it).

8. Board the other side - Board the second side with joints staggered at least one stud bay from the first; mark service positions.

9. Joints and corners - 3–5 joints filled with compound and taped; cut corners from a single board as an L-shape — never butt two boards at a corner.

10. Sand and accept - Sand flat when dry and check flatness, verticality and hollow spots.

Why corners need a one-piece L cutIf two boards butt at a corner, the joint sits exactly where stress concentrates and will crack within 3–6 months. Do it properly: cut one full board into an L, carry it at least 300 past the corner, and move the joint onto the straight run.

04System 2: Ceiling

Figure 2 Joint treatment Leave a 3~5 joint, fill with compound, bed the tape, second coat to level; every joint must land on framing.

1. Install main runners - U38/U50 main runners, hangers at ≤1200, camber 1/200–1/300.

2. Install furring channels - C50 furring channels at 400 (9.5 board) or 600 (12 board); connect to the main runners with clips and level the underside.

3. Mark joint lines - Set out to the board size; stagger joints between adjacent rows by ≥300, and every joint must land on a furring channel.

4. Board - Lay boards with the long edge across the furring channels; self-drilling screws φ3.5×25 at 150–170 spacing, 10–15 from the edge, heads sunk 0.5–1 mm without breaking the paper.

5. Leave gaps - 3–5 between boards; 5–8 between board and wall (sealant or edge trim).

6. Jointing - Fill with compound → bed joint tape → second coat to level → sand when dry.

7. Reinforce openings - Frame the perimeter of light fitting and diffuser openings; independent hangers for loads >3 kg.

8. Corners and steps - Cut corners from a single board; use full boards on step fascias with staggered joints.

05System 3: Direct Fixing (adhesive)

For flat concrete or brick walls and refurbishment of existing walls, without losing much floor space.

1. Prepare the substrate - Remove dust, grease and hollow areas; flatness ≤3 mm/2 m; prime with bonding agent where absorption is high.

2. Set out - Snap the joint lines and level lines, with joints staggered.

3. Apply adhesive - Use gypsum-based adhesive or a dedicated board adhesive in ribbons or dabs: 50 wide ribbons around the perimeter, dabs at ≤300 in the middle.

4. Fix the board - Press by hand and tap with a rubber mallet over a wood block so the adhesive spreads evenly; check with a straightedge as you go.

5. Temporary support - Wedge the bottom with timber wedges and remove after 24 h.

6. Joint treatment - As for partitions; leave a 5 gap at the ceiling junction.

Limits of direct fixingWhere the substrate is weak (dusting, hollow), the wall is damp, or acoustic or fire-rated construction is required, do not use direct fixing — build a framing system instead.

06Quality Acceptance

Table 6-1 Permissible deviations

07Common Problems

Table 7-1 Typical defects

08Product Storage and Handling

Figure 3 Stacking Gypsum board must be stored flat; standing on edge bows it under its own weight, and floor moisture attacks the paper face.

Table 8-1 Storage conditions

Handling: when carrying upright, keep the board face parallel to the body at ≤15° from vertical, and never carry a long board flat by its middle (it will break); for short moves two people carry by the edges. Apply first-in-first-out (FIFO).

09Transport and Safety

• Level vehicle bed, dunnage at ≤600 centers, stack flat, stack height ≤1.2 m;

• Cover with a waterproof tarpaulin throughout; no rain exposure;

• Gypsum board is heavy — use two or more people for loading and unloading and wear cut-resistant gloves;

• Cutting creates dust; wear a mask and goggles;

• Wear a harness for work at height; never stand on the framing; hot work inside the ceiling requires a hot work permit.

10Appendix: Checklists

10.1 Goods receiving

• □Type (standard / water-resistant / fire-resistant) matches the order

• □Thickness, size and batch number consistent

• □Paper face unbroken, no damp staining

• □Edges straight, no chipped corners

• □Quality inspection report supplied with the goods

10.2 Before installation

• □Framing system accepted

• □Services embedded

• □Corner L-cut detail agreed

• □Jointing compound and tape on site

• □Ambient temperature ≥5 ℃

11Frequently asked questions

Should studs be at 400 or 600 mm?

Use 600 mm as standard. Go to 400 mm with 9.5 mm board, walls over 3 m high, wall-hung cabinets or sanitaryware, or a fire rating.

Why leave a 3–5 mm joint between boards?

The gap lets compound key into the joint and absorbs small board movement. Boards butted tight leave compound as a thin skin on the surface, which cracks as it dries and shrinks.

Do double-layer boards really need staggered joints?

Yes. Offset the layers by at least 300 mm and never line them up with joints on the far face, or the joint runs straight through the wall and both sound insulation and fire integrity drop.

Why cut corners from one board?

A corner concentrates stress, and a butt joint there opens under minor settlement or impact. An L-shaped board moves the joint at least 200 mm away from the corner.

Can moisture-resistant board be used in a shower?

Not in direct water. It resists damp but is not waterproof; a shower needs a waterproof membrane under tile, or fiber cement or calcium silicate board.

How do I stop ceiling joints from cracking?

Furring at 400 mm, joints staggered at least 600 mm, screws that do not tear the paper, and three coats of compound with tape. Add expansion joints where a ceiling exceeds 36 m².

About Pandaboard

Guangzhou Panda Commercial Development Co., Ltd. · Pandaboard / PEIDA

We manufacture and export gypsum board, mineral fiber and fiberglass ceiling tiles, calcium silicate and magnesium oxide boards, fiber cement board, aluminum ceilings, WPC and SPC wall panels, exterior decking, fencing and handrails, together with the matching grid and framing systems. The methods on this page are compiled from product behaviour and standard trade practice; for any project, follow the approved drawings, local codes and the specification confirmed on your order.

Website: www.pandamanufacturer.com Contact sales: contactus

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Guangzhou Panda Commercial Development Co., Ltd. · Pandaboard / PEIDA
This guide is technical information for specifiers and installers; it does not replace project drawings or local codes.