Taping and Jointing Techniques: Joint Tape, Three-Coat Finish, Feathering and Avoiding Joint Cracking

Summary

Jointing and taping is the finishing trade for drylining — the work that makes the difference between a surface that looks like plasterboard and one that looks like traditional plaster. It requires patience, good tools, the right materials, and an understanding of why each step exists. Rushed jointing is the single biggest cause of visible joints and callbacks after decoration.

The UK drylining industry uses two approaches to finishing: jointing and taping (the American-derived system using compound and tape) and skim plastering (a thin coat of finishing plaster over the board surface). Skim plastering is more common in UK residential construction and gives a harder, paint-ready surface. Taping and jointing is standard in commercial fit-out and is gaining ground in residential new build because it is faster and requires no specialist plasterer.

This article covers taping and jointing. See skim coat for skim plastering technique.

Key Facts

• Joint tape — reinforces the joint between boards; two types: paper tape (for flat joints and internal corners) and fibreglass mesh tape (for flat joints only — do not use in corners)
• Paper tape — 50mm wide kraft paper with a centre crease; stronger than mesh in corners; the correct tape for all internal angles
• Fibreglass mesh tape — self-adhesive; faster to apply than paper; provides better crack resistance in flat joints when embedded in compound; more expensive
• Jointing compound — setting type (powder, mixed with water; hardens by chemical reaction) vs drying type (pre-mixed in tubs; hardens by water evaporation)
• Gyproc EasiFill — setting-type compound (powder); workable time approximately 20–60 minutes depending on product; hard when set; suitable for filling and embedding tape
• Gyproc Topping Compound — drying type; pre-mixed; applied in thin coats for finishing and feathering; must dry completely between coats
• Three-coat system — Coat 1 (tape coat): embed tape in compound; Coat 2 (filler coat): broad fill over tape, feathered 150mm each side; Coat 3 (finish coat): skim-thin final coat feathered 250mm+ each side; sand when dry
• Feathering — the technique of reducing compound thickness gradually to zero at the edges of the coated area; avoids a visible ridge
• Drying time — varies with temperature, humidity, and coat thickness; minimum 24 hours between coats in normal UK conditions; 48 hours in cold or damp conditions
• Temperature — jointing compound must not freeze; do not apply at temperatures below 4°C; never apply to a frozen or frost-affected board
• Angle bead — galvanised or plastic bead fixed to external corners before jointing; provides a straight corner and protects against chipping
• Scrim tape — alternative term for fibreglass mesh tape; do not confuse with corner tape (which is paper)
• Flex — Gyproc Flex is a pre-mixed flexible jointing compound specifically for expansion joints and areas subject to movement
• Skim after jointing — some specifications require a full skim coat over jointed boards; ensures consistent surface texture and hides any remaining joint marks

Quick Reference Table

Detailed Guidance

Tools Required

A well-equipped jointing kit:

• 125mm (5") broad knife — tape coat and second coat on flat joints
• 200mm (8") broad knife — finish coat on flat joints
• 250mm (10") broad knife — final feathering coat
• Inside corner knife (double-edge tool) — finishing internal angles in one pass
• Mud pan (hawk or rectangular pan) — holds compound while working
• Compound mixer (paddle mixer on drill) — mixing powder compounds
• Pole sander with 120-grit screen — sanding before decoration
• Spotlight or raking light — reveals imperfections during sanding
• Clean water source — mixing powder; cleaning tools

Coat 1 — Tape Coat

The tape coat embeds the joint tape in compound and creates the bond that prevents cracks. If this coat is applied too thinly, the tape will not adhere properly. If too thickly, the tape will bubble or wrinkle.

Flat joints:

1. Apply a ribbon of EasiFill compound to the joint, approximately 75mm wide, 2mm thick
2. Centre the joint tape over the joint, press into the wet compound from the middle outward
3. Draw the broad knife at a shallow angle along the tape to firmly embed it, squeezing out air bubbles
4. Apply a thin skim of compound over the tape (1mm max) to fill the recessed edge of the tapered board
5. Allow to fully harden before coat 2

Most plasterboard is tapered-edge (TE) — the board face is slightly recessed at the joints, leaving room for 2–3 coats of compound to build flush with the board face. This is the recessed joint (RJ) system. Cut-board joints (where the cut edge of the board falls in the middle of a run) do not have a recess — these require a wider feather zone and are harder to finish invisibly.

Internal corners (paper tape):

1. Apply compound to both faces of the corner
2. Cut paper tape to length; pre-crease along the centre fold
3. Press tape into the corner, embed firmly with the corner knife or broad knife
4. Allow to harden

Internal corners — mesh tape (do not use): Fibreglass mesh tape in internal corners is a common error. The mesh does not fold cleanly and tends to push away from the corner under compound, leaving a ridge or a joint crack. Paper tape is mandatory in internal corners.

Coat 2 — Filler Coat

Apply after Coat 1 is fully set/dry. This coat builds up the recessed area around the tape to near-flush with the board surface.

1. Apply Topping Compound or EasiFill with the 200mm broad knife; wider than Coat 1
2. Feather the edges: reduce the compound thickness to zero over approximately 75mm each side of the joint
3. The centre of the joint should be flush or very slightly proud (0.5mm) to allow for shrinkage
4. When dry, inspect with a raking light — any ridges, bubbles, or hollows must be filled before Coat 3

Coat 3 — Finish Coat

The finish coat requires the most skill. It must be thin (0.5–1mm), smooth, and feathered wide enough that the edge is invisible after painting.

1. Use Topping Compound only (never setting-type for the finish coat — it does not sand as smoothly)
2. Apply with the 250mm broad knife in long, smooth strokes; reload the knife sparingly
3. Feather at least 300–350mm either side of the joint centre; on very long runs, feather wider
4. Work toward natural light where possible — it reveals ridges as you work
5. Allow to dry completely (at least 48 hours in typical UK conditions; 72 hours in winter)
6. Sand with 120-grit screen on a pole sander; circular motion, then finish with long strokes parallel to the joint
7. Check with raking light; re-coat any visible imperfections, re-sand when dry

External Corners

External (protruding) corners are finished with angle bead — a galvanised or PVC-coated metal strip with perforated flanges. The bead provides a hard straight edge that resists chipping and makes jointing the corner much easier.

1. Fix bead to corner with plasterboard nails or dabs of setting compound; check plumb with level
2. Apply compound to both flanges simultaneously with the broad knife; feather out 100mm from the bead nose
3. Three-coat process as for flat joints
4. Final result: a crisp, sharp corner that can be decorated without visible bead flanges

Why Joints Crack

Joint cracking after decoration is the most common drylining complaint. Causes:

Screw Heads and Butt Joints

Screw heads and butt joints (non-tapered board edges) require the same three-coat process as tapered joints but with different geometry:

Screw heads: small indentations; fill with EasiFill, allow to set, skim-coat to flush. No tape required.

Butt joints (cut edges): the wider the feather zone the better — aim for 400mm either side of the joint centre, using the widest knife available. A butt joint finished to the same width as a tapered joint will be visible at a raking angle. The ideal solution is to minimise cut-edge butt joints by planning board layout carefully.

Frequently Asked Questions

Should I skim plaster over jointed boards?

It depends on the finish quality required and the substrate. A perfectly jointed surface, sanded and correctly decorated with two coats of mist coat then emulsion, can be invisible. However, skim plastering gives a harder, more even surface that shows less texture variation and hides any residual compound marks. For high-specification residential projects, skim plastering (2mm Thistle MultiFinish or similar) over jointed boards is the most reliable way to achieve a Level 5 (premium) finish. For commercial and standard residential, jointing and careful decoration is sufficient.

How do I avoid seeing the joints after painting?

The main causes of visible joints after painting are:

1. Insufficient feathering on the finish coat (ridge visible in raking light)
2. Wrong paint preparation (first coat applied to dry compound without a mist coat — the mist coat seals the compound and prevents uneven absorption)
3. Single coat of paint (always apply minimum two finish coats)
4. Gloss or sheen paint over imperfectly finished joints (use matt or very low-sheen paint; it hides surface variation better than silk)

Apply a mist coat (60:40 emulsion/water dilution) as the first coat over all jointed surfaces. This seals the board and compound uniformly, preventing different absorption rates (which cause joint flash-through) on the finish coats.

What is a Level 5 finish?

Level 5 is a US ASTM standard designation (ASTM C840) increasingly referenced in UK specs for premium finish quality. It requires the three-coat taping process plus a full skim coat of compound over the entire board surface. This eliminates all texture variation between the board face and the compound-covered areas. Level 5 is specified for areas with critical lighting (e.g. feature walls, gloss finishes) or where final finishes are high-sheen. Most UK residential projects are Level 4 (three-coat jointing, sanded smooth, mist coat, two coats of paint).

Regulations & Standards

• BS EN 13963:2014 — jointing materials for gypsum boards; classification of tapes and compounds

• BS EN 520:2004 — gypsum plasterboards; paper-faced board specification including tapered edge geometry

• ASTM C840-20 (US standard, increasingly referenced in UK specs) — application and finishing of gypsum board

• British Gypsum Finishing Guide — product-specific application instructions; available in the White Book or as a standalone PDF

• British Gypsum Jointing Compounds — EasiFill, Topping Compound, and Flex product data

• British Gypsum Finishing Guide — full three-coat technique guide

• CITB Drylining Training — NVQ Level 2/3 Drylining includes jointing assessment

• british gypsum systems guide — board types and tape specifications

• skim coat — alternative finishing method using plaster over board

• plasterboard types — board selection affecting joint finish

• drylining on masonry — substrate preparation before boarding and jointing