HOW-TO · READY-MIX

How to plaster a wall (internal & external)

A good plaster coat is the base for everything that follows. Here is how to plaster internal and external walls with SUMO Ready-Mix Plaster.

LEVEL

Intermediate

TIME

10–15 mm coat + cure

STEPS

WHO THIS IS FOR

Masons and applicators plastering brick, block and concrete walls.

Plastering looks simple and goes wrong easily — most problems are debonding from a poor background, or shrinkage cracks from fast drying. SUMO Ready-Mix Plaster gives a consistent, low-crack coat for internal and external walls when applied to a prepared, dampened background and cured.

This guide covers the full wall-plastering method.

BEFORE YOU START

What you’ll need

PLASTER40 kg bagReady Mix Plaster40 kg→

Trowel, hawk, straightedge (darby), float

Drill + paddle, clean water

THE METHOD

Step by step

Prepare and dampen the background

Rake joints, remove dust and loose material, and dampen the wall evenly. A dry, dusty wall is the top cause of plaster debonding.

WATCH OUTNever plaster onto a dusty or bone-dry wall — clean and dampen it first.

Mix the plaster

Add SUMO Ready-Mix Plaster to clean water and mix to a smooth, workable, lump-free mortar. Mix batches you can apply before they stiffen.

PLASTERPRODUCT USED IN THIS STEPReady Mix Plaster40 kg→

Apply and press well in

Apply an even coat to the required thickness, pressing the plaster firmly into the wall. Build thickness in layers where needed rather than one heavy coat.

Rule off flat

Rule off with a straightedge to a true, flat surface, filling hollows as you go.

PRO TIPRule off while the plaster is still workable — chasing hollows once it stiffens is much harder.

Float and cure

Float to the finish you want, then keep the plaster damp-cured so it gains strength without shrinkage cracks. Follow with wall putty before painting.

WALL PUTTYPRODUCT USED IN THIS STEPWall Putty40 kg→

AVOID THESE

What to avoid

!Poor background prep

Dust, grease and dryness cause debonding. Clean and dampen first.

!Too-thick coats

Heavy single coats slump and crack. Build up in layers.

!No curing

Fast drying cracks plaster. Keep it damp-cured.

QUESTIONS

FAQ

How do you plaster a wall?+

Prep and dampen the background, mix SUMO Ready-Mix Plaster, apply an even coat pressed well in, rule off flat, float and cure.

Why does plaster crack?+

Usually fast drying (no curing), too-thick coats, or a weak/dusty background. Dampen, build in layers and cure.

What goes on after plaster?+

Once cured, apply SUMO Wall Putty for a smooth, paint-ready surface, then prime and paint.

THE KIT

Products used in this guide

PLASTERSUMO PRODUCTReady Mix Plaster40 kg→WALL PUTTYSUMO PRODUCTWall Putty40 kg→SEALCRETESUMO PRODUCTAcrylic Waterproofing Liquid1 kg→FLOORSCREEDSUMO PRODUCTFloorscreed40 kg→

NOT SURE ON YOUR JOB?

Send us your substrate and tile size — our technical team will confirm the exact method.

Read the datasheet →