Plastering: A Practical Guide to Strong, Smooth Walls (South Africa)

Plastering is the process of applying a protective and decorative coating to masonry or concrete walls and ceilings—most commonly a sand-cement mix—so surfaces are smoother, more weather-resistant, and ready for paint or other finishes. Industry guidance notes that sand-cement plaster is widely used for both protection and appearance in building work. Learn more in this South African-focused CemBrick plastering guideline PDF.

What plastering does (and why it matters)

Good plastering helps:

• Protect masonry from rain penetration and weathering (especially exterior walls).
• Improve appearance by straightening and smoothing surfaces.
• Prepare surfaces for paint, tiles, or skim coats.

For a deeper overview of what drives plaster performance (materials, workmanship, and common issues), see AfriSam’s “Your Guide to Plastering” PDF.

Plaster types you’ll see most often

1) Sand-cement plaster (the common “traditional” option)

This is the standard exterior/interior wall plaster in many builds. The goal is a cohesive, workable plaster with good water retention and durability—especially when applied correctly and cured properly. AfriSam’s Successful Plastering PDF explains key material choices and application risks like early cracking from moisture loss.

2) Gypsum plaster / skim plaster (smooth interior finishes)

Gypsum plaster systems are popular for achieving very smooth internal finishes, often over suitable substrates with proper priming and preparation. A helpful overview is Gyproc South Africa’s guide to gypsum plaster, which covers surface prep and selecting the right plaster type for the job.

Materials that make or break plastering

Cement compliance and quality

South African builder guidance highlights that cement sold in South Africa must meet relevant cement standards and NRCS requirements, and bags should be clearly marked (including LOA information). See The Concrete Institute / Concrete Society SA leaflet (2024) on concrete, mortar & plaster mixes.

Sand quality (often underestimated)

Sand is the biggest component in a plaster mix and strongly affects strength, workability, cracking risk, and finish quality. Plaster sand should be clean and free of organic material. This is emphasized in South African plastering guidance like AfriSam’s plastering guide PDF and PPC’s bricklaying & plastering PDF.

Avoid “too rich” mixes and overly thick coats

Overly cement-rich mixes can increase shrinkage cracking risk. Guidance also recommends limiting plaster thickness to manageable coats (e.g., not exceeding about 15 mm per coat), plus good curing and protection from sun and wind. This is clearly stated in AfriSam’s “Your Guide to Plastering” PDF.

Step-by-step: how plastering is typically done

Below is a practical, standard approach aligned with South African DIY/pro guidance.

1) Prepare the surface properly

• Remove dust, loose material, and any contamination.
• Repair major cracks or defects before plastering.
• Control suction/absorption where needed so the plaster doesn’t lose water too fast (a key driver of early cracking). This risk is discussed in AfriSam’s Successful Plastering PDF.

2) Mix correctly (consistency matters)

PPC’s plastering guide describes mixing cement and plaster sand to uniform colour, then adding water gradually to reach a workable paste. Use PPC’s “How to plaster a wall” PDF as a straightforward reference.

3) Apply in controlled coats

• Apply evenly and keep thickness consistent.
• Where thickness needs exceed a single coat, apply in layers (with proper technique and timing). AfriSam provides practical application “top tips” in AfriSam’s plaster application top tips PDF.

4) Cure and protect the plaster

Rapid drying from wind and direct sun can cause early shrinkage cracking. Protect fresh plaster and cure appropriately—this is repeatedly emphasized in AfriSam’s plastering guidance.

Common plastering problems (and what usually causes them)

Hairline cracking

Often linked to shrinkage from water loss, overly rich mixes, poor sand grading, high suction substrates, or exposure to sun and wind without enough curing/protection. See the causes and prevention pointers in AfriSam’s “Your Guide to Plastering” PDF.

Efflorescence (white salts)

Cement type and damp exposure can influence efflorescence risk, especially on plinths or areas exposed to persistent moisture. AfriSam’s technical plaster guidance discusses cement selection considerations for damp conditions in Successful Plastering (AfriSam) PDF.

Poor adhesion or hollow spots

Usually tied to surface contamination, incorrect prep, or application onto unstable/dirty substrates. Good substrate prep practices are reinforced across South African plastering guides such as CemBrick’s plastering guideline PDF.

Plastering standards and specifications (South Africa)

Public construction specifications commonly reference SANS 2001-EM1 for cement plaster work requirements. An example municipal building works specification explicitly states cement plasterwork must comply with SANS 2001-EM1 in its section on cement plaster. See Emalahleni LM “PPS Building Works” PDF.

How to choose the right plastering approach for your project

• Exterior walls: Prioritise durability, moisture resistance, and correct curing/protection. Use guidance like AfriSam’s plastering guide for best-practice thickness and curing.
• Interior walls (high-finish): Consider gypsum skim/finishing plasters where suitable, following proper priming and system guidance like Gyproc’s gypsum plaster guide.
• DIY vs contractor: DIY can work for small areas if you follow proven methods like PPC’s plastering PDF, but larger exteriors or highly visible finishes often justify experienced plasterers due to the risk of cracking, debonding, and uneven walls.

Plastering maintenance tips

• Fix water sources fast (leaks, rising damp, failed gutters) before patching plaster—otherwise damage will return.
• Repaint exteriors on a maintenance cycle to reduce water ingress.
• Address cracks early; small cracks can become pathways for moisture, especially on exterior walls.

If you’re building or renovating in South Africa and want plaster that lasts, follow proven local guidance on materials, coat thickness, workmanship, and curing—because most plaster failures come from shortcuts in those four areas, as highlighted throughout AfriSam’s plastering resources and CemBrick’s plastering guideline.