South African houses are drawn in millimetres, built in brick and roofed in concrete tiles or steel sheet. Those three facts quietly reorganise a project: most of the DIY content online assumes imperial measurements, timber-framed walls and 25 kg cement bags — good reading, wrong arithmetic for an SA build.
This guide covers the conventions that change planning most: how drawings and materials are measured, how walls and roofs are commonly built, where the electrical rules draw the DIY line, and how water is typically handled. Practice varies by province, builder and era — everything here is typical, not universal.
South African plans and building trades work fully in metric: dimensions in millimetres, materials in kilograms and cubic metres. Walls are commonly double brick — two skins, about 220 mm thick — or cavity brick where wind-driven rain is heavy; face brick is often the finished exterior. Roofs are typically concrete tiles or steel sheeting, corrugated or IBR. Supply is 220–230 V and fixed wiring is certified electrician work. Cement comes in 50 kg bags — double the 25 kg bags common elsewhere — and sand arrives by the cubic metre. This site’s calculators are metric-first, so they map straight onto SA practice.
The Drawing Speaks Millimetres
Ask for a room size on a South African drawing and the answer is one number: 3600. Working drawings are dimensioned in millimetres throughout — a door height is 2100, a boundary wall 1800 high, a slab 85 thick. Nobody writes 3.6 m on a plan; the unit is understood.
The brick sets the module. A standard stock brick — clay or cement — runs about 222 × 106 × 73 mm; with a 10 mm joint that is roughly 232 mm of wall per brick length and 83 mm per course, which is why masonry dimensions land on numbers that look odd until you see the module.
The consequence for imported advice: convert before it meets the plan. A 12 ft (3.66 m) span is 3660 mm on paper — and rounding it to 3600 changes the brick count, the tile count and the sheet lengths at once.
Walls: Two Skins, Sometimes a Cavity
The typical standalone South African house is masonry, not timber frame. The common build is double brick: two skins laid in stretcher bond, about 220 mm thick overall, tied together with wall ties and plastered on the inner face. Where wind-driven rain is a serious load — the Western Cape coastal belt in particular — the two skins are separated by a roughly 40–50 mm cavity instead. The outer skin takes the weather, any water that crosses it runs down the cavity face, and weep holes at the bottom let it out. Cavity work is less forgiving: nothing should bridge the gap, and ties and openings need careful detailing.
Single-leaf walls — one skin, about 110 mm — turn up on outbuildings and boundary walls; interiors are commonly brick too, though drywall partitions appear in renovations.
Masonry changes the project: heavy walls sit on strip footings, shelves hang from plugs drilled into brick, and new pipe runs mean chasing channels, not opening a cavity. For quantities, count units by wall area per skin — the Brick & Block Calculator is built for exactly that, and knows about double skins.
Face Brick: The Finish That Isn’t Painted
Face brick is the exterior skin left visible — a facing unit whose colour runs through the clay or cement, laid with mortar joints as the only detail. It is commonly chosen because the maintenance cycle is measured in decades: there is no paint to renew, and the wall weathers rather than wears out.
What does age is the mortar: joints erode eventually, and repointing means matching joint profile and mortar colour — specialist work. Extending a face-brick house is its own exercise, because batches vary in tone and mortar colour changes the look as much as the brick; common practice is the closest match with an accepted difference. The other half of SA exteriors is the plastered wall — cement stock bricks rendered and painted — which sits on a painting cycle that face brick simply declines.
Roofs: Concrete Tiles, Corrugated and IBR
Two coverings dominate. Concrete roof tiles — profiles such as the Double Roman — hook over timber battens laid on under-tile membrane. Interlocking concrete tiles typically run about 10 per square metre, so a 150 m² roof plane is roughly 1 500 tiles plus ridge and hip caps, lapped to suit the pitch.
Sheet steel is the other tradition, in two common profiles. Corrugated is the classic sinusoidal wave, commonly 762 mm cover per sheet. IBR — inverted box rib — is the square-shouldered trapezoidal profile, commonly 686 mm cover, typical of newer roofs. Both are fixed with roofing screws and sealing washers, lapped by profile. Profiled sheeting generally suits lower roof pitches than tiles, which want a steeper roof to shed water reliably. Under the covering it is usually timber: SA pine trusses or rafters with battens or purlins at spacings set by the covering manufacturer’s tables.
Electricity: 220–230 V and the Compliance Certificate
Mains supply is nominally 230 V at 50 Hz — commonly spoken of as 220–230 V — through the familiar large round three-pin plug. The part that reshapes a project: fixed electrical work is, in general, legally reserved for qualified electricians. New installations, alterations and additions must be certified — a Certificate of Compliance, issued by the electrician, recording that the work follows the wiring rules — and that certificate is routinely called for when a property changes hands.
The practical DIY boundary sits at the plug and the unplugged: fitting a plug top is one thing; adding a socket, moving a light point or touching the distribution board is certified work. Treat this as the shape of the rules, not legal advice — but plan on the assumption that anything fixed into the wiring is an electrician’s job, and file the certificate with the drawings.
Cement in 50 kg Bags, Sand by the Cubic Metre
South African cement comes in 50 kg bags. That single fact quietly breaks recipes imported from the UK and much of Europe, where the standard bag is 25 kg. A mix written as one bag of cement to six of sand means a different mass in each country; two 25 kg bags make one SA bag, so bag-count arithmetic halves or doubles across the border.
On site, mixes are gauged per bag or per wheelbarrow, and concrete is spoken of in volume ratios — 1:2:4 cement, sand and stone for a classic foundation mix. Sand and stone arrive loose by tipper, sold by the cubic metre, half-metre loads common on smaller jobs; bagged sand exists for patch work, but any job past a few barrow-loads thinks in cubic metres. That is the same arithmetic this site’s tools use, with one trap: the Mortar and Render & Plaster Calculators report cement in 25 kg bags — halve the counts for SA’s 50 kg bags.
Rainwater Tanks and Boreholes
Water storage is normal practice across much of the country. Rainwater tanks — commonly 2 500 L and 5 000 L polyethylene units — feed from the gutters and serve gardens, pools and supply interruptions. The arithmetic is friendly: 1 mm of rain on 1 m² of roof yields 1 litre, so 100 mm on a 100 m² roof is 10 000 L before losses — figure on collecting about 80%. The Rainwater Collection Calculator runs the sum for your roof.
Boreholes are common in many inland regions: a drilled hole, a submersible pump and a pressure tank, sometimes with filtration. Registration and metering rules vary by municipality — check locally before drilling.
How This Site’s Calculators Map to SA Practice
Everything on this site is metric-first — millimetres in, square metres, cubic metres and litres out — the language SA drawings and merchants already speak. Four tools map especially well:
- Brick & Block Calculator — units per m² from unit and joint size, single or double skin; the 222 × 106 × 73 stock brick slots straight in.
- Mortar Calculator — wall and joint dimensions give mortar volume, cement and sand; it reports 25 kg bags, so halve for SA’s 50 kg bags.
- Render & Plaster Calculator — plaster is the standard interior finish over masonry; area and coat thickness give cement and sand in the same units.
- Rainwater Collection Calculator — roof area and rainfall give litres per event and per year at a typical 80% collection efficiency.
The one place to read the fine print is structural timber: the deck calculator works from North American IRC span tables in nominal lumber sizes, and timber sections and grades differ by country — see Timber and Lumber Sizes Around the World before sizing framing.
Common Mistakes
- Ordering from an imperial guide. Convert feet and inches to millimetres before anything meets an SA plan or merchant.
- Halving the wrong way. SA cement bags are 50 kg; a recipe written for 25 kg bags needs its bag count halved for SA bags.
- Assuming a paintable wall. Face brick is the finish — plan to match it, not coat it.
- DIY on fixed wiring. Work that needs a Certificate of Compliance needs an electrician.
- Forgetting the sand heap. Loose aggregate arrives by the cubic metre, and 2 m³ of sand needs somewhere to sit.
Plan It With the Mortar Calculator
A double-brick wall carries three quantities: units, mortar and plaster. The tools speak SA’s units — dimensions in millimetres, sand out in cubic metres, cement out in bags (halve the 25 kg counts for SA’s 50 kg bags). Run the Brick & Block Calculator for the count, the Mortar Calculator for the mix, the Render & Plaster Calculator for the finish — and the Rainwater Collection Calculator for the tank.
Frequently Asked Questions
Why are cement bags 50 kg in South Africa?
Because 50 kg is the bag mass the local industry settled on — double the 25 kg bag common in the UK and much of Europe. The consequence is arithmetic: recipes written for 25 kg bags need their count halved for SA bags; two 25 kg bags make one SA bag exactly.
Can I do my own electrical work in South Africa?
In general, not on fixed wiring. Fixed electrical work is reserved for qualified electricians and must be covered by a Certificate of Compliance, routinely called for when a property changes hands. The DIY boundary sits around plug tops and unplugged appliances. Treat this as the general shape of the rules, not legal advice.
What is the difference between double brick and a cavity wall?
Both are two skins of masonry. Double brick ties the skins into a wall about 220 mm thick, plastered on the inside. A cavity wall separates the skins by roughly 40–50 mm so that water crossing the outer skin drains down the cavity and out through weep holes — the usual build where wind-driven rain is heavy, such as parts of the Western Cape coast.
What is IBR roof sheeting?
A steel roof sheeting profile — inverted box rib — with square-shouldered trapezoidal ribs, commonly 686 mm cover per sheet. It sits alongside corrugated, the sinusoidal profile at roughly 762 mm cover. Profiled sheeting generally suits lower roof pitches than concrete tiles, which want a steeper roof.
Related MyHouseLogic Guides
- Mortar Mix Ratios Guide — mix classes, per-bag arithmetic and sand volumes for brickwork.
- Brick Wall Quantity Guide — counting units by wall area, skins and joint size.
- Timber and Lumber Sizes Around the World — the same regional mapping for structural timber and span tables.
- Homes Around the World — the collection of regional measurement and planning guides.
- Field Guide library — every MyHouseLogic guide, each tied to a calculator.
The bottom line: South African homes are metric, masonry and brick-skinned. Plan in millimetres, count walls in skins, order cement in 50 kg bags and sand by the cubic metre — and leave the fixed wiring to a certified electrician.