One of the most common frustrations in early-stage architectural and engineering work is tracking down reliable contour data. You check Google Earth. You dig through your metro’s GIS portal. You try Google Maps. And you come up empty — or close enough to it that the data isn’t useful.

Here’s a tool that solves that problem.

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One Map: Contours for Any South African Site

One Map (onemap.co.za) is a subscription-based mapping service with a free tier that gives you access to contour overlays for sites across South Africa. For initial feasibility and concept work, it’s one of the most practical tools available locally.

The contours are displayed at 5 metre intervals — enough resolution for early site analysis, section studies, and understanding the general topography of a site before you’ve commissioned a survey.

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How to Turn Contours On

The interface is a little clunky, so here’s the exact sequence:

1. Open your site in One Map.
2. Click Workspace and Layers in the side panel.
3. Select Overlays.
4. Find NGI and enable Relief Lines.

You can toggle this layer on and off as needed. Once it’s active, you’ll see contour lines across your site with elevation values labelled directly on the map.

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What It’s Good For

• Early site analysis — understanding slope, drainage direction, and level changes before a survey is commissioned.
• Concept design — informing split-level decisions, retaining wall locations, and building placement.
• Client presentations — a quick visual read of the topography that non-technical clients can follow.
• Rural and peri-urban sites — particularly useful where municipal GIS data is sparse or outdated.

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A Word of Caution

One Map contours are useful for initial thinking and planning. They are not a substitute for a registered land surveyor’s certified contours, which you’ll need before submitting for local authority approval or moving into detailed design. Treat this data as a starting point, not a deliverable.

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Other Sources Worth Knowing

If One Map doesn’t suit your workflow, a few alternatives are worth having in your toolkit:

• Chief Directorate: National Geo-spatial Information (NGI) — the underlying data source One Map draws from. You can sometimes download raw DXF or shapefile contours directly for use in CAD or Revit.
• SANSA Earth Observation — useful for large rural sites where NGI coverage becomes patchy.
• Google Earth Pro (free desktop app) — the elevation profile tool along a path can be handy for quick cross-sections, and you can export KMZ overlays.

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Whenever we find a tool that saves time on the unglamorous parts of the job, we’ll share it here. If you have your own go-to resources for site data in South Africa, drop them in the comments — we’d like to know what others are using.

https://youtu.be/o9sdb4KF7Yk

If you’re planning to build, extend, or develop a property in South Africa, you’ve probably come across terms like coverage, floor area, and FSI in your dealings with the local authority. Whether you’re in Cape Town, George, Nelson Mandela Bay, or dealing with your local municipality, they’ll ask you about these figures — and getting them wrong can delay or derail your project.

Here’s a simple breakdown of what each term means.

Coverage: How Much of Your Site Are You Building On?

Coverage refers to the footprint of your building — in other words, how much of your site is physically covered by the structure when you look at it from above.

Let’s say you have a 1,000 m² site and your building covers 500 m² of it. Your coverage is 50%.

This matters because your zoning scheme sets a maximum coverage limit for your property. It also dictates your building lines (how close to the boundary you can build) and what the property can be used for. Exceed the coverage limit and your plans won’t be approved.

Floor Area: The Total Space Across All Storeys

Floor area is different from coverage because it accounts for every level of the building. If your 500 m² footprint has two storeys, your total floor area is 1,000 m². Coverage stays the same — the building still only covers 500 m² of the ground — but the floor area doubles.

This is why multi-storey buildings can provide significantly more usable space without necessarily exceeding coverage limits.

FSI: Floor Space Index

FSI stands for Floor Space Index, and it’s the ratio that controls the maximum total floor area you’re allowed to build on a given site.

The formula is simple:

Maximum Floor Area = Site Area × FSI

So if you have a 1,000 m² site with an FSI of 2, you’re permitted to build up to 2,000 m² of floor space in total. You can find your property’s FSI in your zoning certificate or by submitting a town planning inquiry to your local municipality.

FSI is particularly useful on multi-storey developments, where you want to maximise the building’s potential without exceeding what the zoning allows.

A Quick Summary

Term	What It Measures
Coverage	The building’s footprint as a % of the site
Floor Area	Total built space across all storeys
FSI	The multiplier that sets your maximum floor area

Need Help Working Out Your Numbers?

If you’re unsure what your property’s zoning allows — or you just want a quick calculation before you start planning — get in touch with us. We work through these figures every day and can give you a clear picture of what’s achievable on your site.

If you’re an architect or built environment professional working on a heritage permit — or even a routine building plan submission — you’ll need to know whether the building you’re working on is older than 60 years.

Why does it matter? Because under the National Heritage Act, any building older than 60 years (or any site on which such a building stands) is protected. That means you need to declare the building’s age in your plans, and getting it wrong has real consequences.

The Obvious Starting Point: Approved Plans

Approved municipal plans are your best source. They’ll tell you when a building was constructed. If you can get them, go to the municipality and request the approved plans on record — that’s your most reliable evidence.

But what if there are no approved plans? That’s where it gets trickier, and where many practitioners get stuck.

The Fallback: The Survey Diagram and General Plan Number

If approved plans aren’t available, look at the survey diagram for the property. The survey diagram records when the land was first surveyed, and crucially, it contains a General Plan number — which tells you when that township or subdivision was established.

For example, a General Plan dated 1983 tells you the land was subdivided in 1983. That gives you a definitive earliest possible date for any buildings on it.

This is a document you can attach to your heritage permit application or building plan submission as supporting evidence of age.

An Important Nuance

The General Plan date tells you when the land was subdivided — not necessarily when the building was constructed. A General Plan from 1984, for instance, doesn’t mean the building was built that year. Construction may have followed a decade later.

That’s why the survey diagram works best as a floor — it establishes the earliest the building could have been built. Pair it with approved plans wherever possible to narrow it down further.

In Summary

Source	What it tells you
Approved municipal plans	Actual construction date — most reliable
Survey diagram / General Plan number	Date the land was subdivided — useful fallback

When approved plans aren’t on record, the survey diagram is a legitimate and useful document to support your application. Know where to find it, and keep it in your toolkit.

I want to show you a very simple guttering system — an easy-peasy guttering system you can do really quickly when you’re working with corrugated iron.

Why is this important? Because people are sometimes too fast to leave projects, to let somebody else take over — to let somebody else take our freedom away from us by telling us it’s too complicated. It isn’t.

The Idea

The whole system is built around a simple 75mm PVC downpipe — the standard kind you’ll get at any Builders Warehouse or Home Depot, along with the little elbows to match.

The trick is this: you split a length of downpipe down the side, then open it up and clip it onto the end of the roof sheet, where it acts as a gutter. The corrugated iron edge sits inside the split pipe, and the rainwater running off the roof feeds straight into it.

I’m not the guy who thought this up — I’ve seen other guys do it before, including a very good friend of mine who has used it on very nice buildings.

The Tools

Nothing fancy: a pair of gloves, a cordless hand drill (mine’s a 14-volt), a crosscut saw, and a level — I like to use a Stanley.

I cut the slit on a table saw, but you don’t need one — you can do it with a handsaw. One warning: be careful of the sharp edges of the corrugated iron. I don’t want to create any accidents with this.

Putting It Together

Split the pipe, open it up, and work it onto the edge of the roof sheet — I prefer feeding the thick end on first. At the corner, an unsplit elbow clamps over the split section, which also helps grip the gutter more firmly around the sheet. Then secure it in place with a screw from your hand drill — that’s all you need to hold the downpipe in position. Do that at each corner and you’re away.

At the bottom end, the downpipe runs into a 200-litre drum — ours was rescued from a dump site; it used to belong to Castrol, but now it belongs to Pebble Spring Farm. From the drum, a few attachments let us run the water off to feed the chickens and the rabbits.

It’s really that easy.

Do the Numbers

Don’t be confused by the size of this very little project — it’s a rabbit hutch and a chicken coop we built here. But the maths is worth looking at.

This little piece of roof is 1 metre wide by 1.5 metres — 3 square metres of roof sheet in total. Here in Port Elizabeth, at 34 degrees south near the coast, we get about 600 to 700mm of rain per year. Over 3 square metres, that’s around 2 kilolitres of water a year — an average of about 5 or 6 litres a day.

The chickens and rabbits are not going to use 5 litres a day. This little unit becomes completely self-sustaining — and the whole system is going to expand to 10, 15, 20 units.

Keep It Small, Keep It Free

Don’t try this on big industrial operations. I’m talking about home projects — a little shed, a little house, a little cottage, a chicken coop, that kind of stuff.

Tell me how it works for you in your environment. We’re looking for easy things, we’re looking for cheap things, we’re looking for stuff you can do yourself — to set yourself free.

Almost everybody knows that before you build something, you have to get a permit. You’ve got to get plans approved, you’ve got to get the zoning in place. But not everybody knows that before you demolish something, you also need a permit.

Where to Get the Application

If you’re in Nelson Mandela Bay, the demolition application form is available online — go to nelsonmandelabay.gov.za and download it. Make sure you’re getting the latest version.

If you don’t have internet access, you can go to the building inspectorate on the fourth floor, in the building opposite the info centre — near where Treasury is, by the Lillian Diedericks building. But honestly, the easiest route is just to get it off the website.

What You Need to Submit

The application comes with a checklist, and it can all be emailed in. You’ll need:

An aerial photograph of the building to be demolished, a locality map, and elevations of the building to be demolished.

And here’s the important one: if the building is older than 60 years, you need a heritage permit before you submit — that’s an application to the provincial heritage authority, ECPHRA. That’s a whole process on its own (we’ll cover it separately). If the building is younger than 60 years, you don’t need one.

You’ll also need to provide proof of age of the building. Don’t be tempted to claim a building is younger than 60 years when it isn’t — that’s fraud, and you can get into serious trouble. I’m not exaggerating when I say jail time is a possibility.

What It Costs

It’s a flat fee — currently R641 — payable to the municipality. They’ll confirm the amount and give you payment details when you submit.

The Bottom Line

That’s the paperwork and the approvals you need in place before you demolish anything. So don’t say you didn’t know — because now I’ve told you.

It’s really not that complicated, but if you need help with this, look us up. And if you’re not in Nelson Mandela Bay, don’t think this doesn’t apply to you — every jurisdiction in South Africa has a similar process. Wherever you are in the country, you’re going to need a demolition permit.