Scrim tape is the quiet hero of a crack-free plastering job. Skip it or use it badly and hairline cracks appear along every board joint within months. This trade guide explains what scrim tape is, what it is used for, the types available, and how to apply it for a joint that stays sound.
What is scrim tape?
Scrim tape is a self-adhesive mesh tape — usually made from fibreglass — used to reinforce the joints between plasterboards before they are skimmed or filled. The open mesh lets jointing compound or plaster pass through and key into it, bridging the joint so that natural movement between boards does not crack the finished surface. Browse our scrim tape range for lightweight and heavy-duty options.
What is scrim tape used for?
Scrim tape has one core job — preventing cracks — and a few closely related uses:
- Reinforcing the joints between plasterboards before skimming or jointing.
- Bridging and repairing cracks in existing plaster and ceilings.
- Covering internal corners and around openings where boards meet.
- Patching small holes and damaged areas before filling.
Types of scrim tape
The right scrim depends on the size of the joint or repair.
Self-adhesive scrim tape
The standard choice for board joints. Self-adhesive scrim sticks straight onto the plasterboard, so it stays put while you apply compound over the top — quick, clean and ideal for day-to-day jointing. Our Lightweight Scrim Tape is a reliable option for everyday work.
Heavy-duty scrim
For wider joints, bigger repairs and areas that take more stress, a heavier, stronger scrim gives extra reinforcement. Monster Scrim is a heavy-duty option designed for larger gaps and demanding repairs where standard tape would not be enough.
Scrim tape vs paper jointing tape
Both reinforce joints, but they work differently. Self-adhesive scrim is faster to apply — it sticks straight to the board and suits setting-type jointing compounds. Paper tape has no adhesive and must be bedded into a layer of compound, which takes longer but gives some plasterers the flattest possible finish on flat joints. For speed and ease, particularly with modern jointing compounds, self-adhesive scrim is the popular trade choice.
How to apply scrim tape
Applied correctly, scrim tape takes seconds per joint. The method is:
- Make sure the plasterboard joints are clean, dry and properly supported.
- Run the self-adhesive scrim centrally over the joint, pressing it down flat with no wrinkles or overlaps.
- Apply your jointing compound or plaster over the tape, working it fully through the mesh.
- Feather the edges out so the joint sits flush with the board surface.
- Once dry, sand lightly and apply a second coat if needed for a seamless finish.
Tips for a crack-free finish
- Keep the tape flat — wrinkles and thick overlaps create ridges that show through the finish.
- Do not stretch the tape; let it sit naturally over the joint.
- Ensure boards are fixed and supported behind the joint — scrim reinforces movement, it does not fix loose boards.
- Use a heavier scrim such as Monster Scrim for wider gaps rather than doubling up lightweight tape.
Scrim tape sizes and widths
Most scrim tape for board jointing is around 48–50 mm wide, which comfortably covers a standard plasterboard joint. Wider and heavier tapes are used for bigger repairs, internal corners and areas that need extra reinforcement. As a rule, match the width to the joint: standard tape for board joints, a wider heavy-duty scrim for larger gaps and patched repairs.
Can you paint over scrim tape?
Not directly. Scrim tape must first be covered with jointing compound or plaster and finished flush with the surrounding surface. Once that coat is dry, sanded and any second coat applied, the wall can be decorated as normal. Painting straight over bare mesh will show the tape texture through the finish, so always skim or joint over it first.
Common scrim tape mistakes to avoid
- Applying the tape with wrinkles or thick overlaps, which create ridges that telegraph through the finish.
- Stretching the tape as it goes down instead of letting it sit flat over the joint.
- Relying on scrim to hold loose boards — it reinforces movement, it does not fix unsupported plasterboard.
- Skimming over the tape too thinly, so the compound does not key fully through the mesh.
- Using lightweight tape doubled up on wide gaps instead of a proper heavy-duty scrim.
Shop scrim tape at The Mastic Shop
We supply trade-quality scrim tape for plastering and repairs. Browse the scrim tape range, pick up Lightweight Scrim Tape for everyday jointing or Monster Scrim for heavy-duty repairs, and explore the full tapes range.
