Whether your extension needs approved plans — who confirms it

Most homeowners start planning an extension without knowing who needs to approve the design — and end up wasting weeks discovering that their chosen builder can't or won't handle it. The question "Does this need approved plans?" should not be an afterthought. It determines whether you'll move forward smoothly or hit a standstill waiting for paperwork that nobody told you was necessary.

The short answer: most extensions *do* need approval. But the person who confirms it, and who gets the approval, depends on what you're building, where you are, and what your local authority requires.

Local authority rules determine whether plans must be approved

Your municipal building control department decides if your extension triggers the need for approved building plans. This is not optional once they require it. If your extension involves structural changes, increases floor area significantly, alters the roof line, affects fire safety, or touches electrical, plumbing or drainage systems, approval is almost certain. Even a small rear room can need formal plans if it changes the building envelope or adds habitable space.

The catch: requirements vary between municipalities. What needs approval in Johannesburg may differ from Durban or Cape Town. Your local authority website usually lists thresholds, but many do not explain them clearly. The safest starting point is to contact your municipal building control office directly and describe what you want to build. Ask explicitly: "Does this extension require approved building plans?" Write down the answer and the name of who gave it. This becomes your baseline.

If approval is required, the authority will tell you what documents they need: architectural drawings, structural calculations, site plans, electrical and plumbing layouts, and so on. These are not light sketches — they are formal engineering documents prepared by registered professionals.

Who submits the plans: builder, architect, or engineer

Once you know plans must be approved, the next step is identifying who prepares and submits them. This is where buyers often go wrong: they assume their builder will handle it, but some builders do not. Others will do it but charge separately. Others subcontract it and take a fee on top.

A qualified architect or structural engineer prepares and stamps the plans, then submits them to the local authority. The builder does not do this — the builder builds according to the approved plans. However, builders often *manage* this process on behalf of the client, which means they hire the architect or engineer, coordinate with the authority, pay for amendments if needed, and include those costs in the quote.

Some builders will say: "You arrange the plans, I'll build to them." This pushes the responsibility onto you. You then have to find and brief an architect or engineer, manage the approval timeline yourself, and pay them directly. This is valid, but it requires you to understand what the plans must show and to communicate clearly with both the professional and the builder.

The clearest way forward is to ask your builder outright: "Will you manage the building plan approval process? If so, is this included in your quote or charged separately?" If they say no, ask them to recommend an architect or engineer, or use Strove to find a registered professional who specialises in small extensions and can guide you through exactly what the local authority needs.

Verification: check they know the rules for your area

Not all builders understand local authority requirements. Some have worked in multiple provinces and assume rules are the same everywhere — they are not. Before committing, ask a potential builder:

• Have you completed extensions in this municipality before?
• Do you know if this type of extension requires approved plans?
• Who do you use to prepare plans, and what is their registration?
• How long does approval typically take here?

If they cannot answer these questions confidently, they may not be the right fit. A builder familiar with your area knows the local authority's preferences, common rejection reasons, and realistic timelines. They also know which engineers or architects work well with that authority.

Building plan approval is not a barrier — it is a protection. Approved plans ensure your extension is safe, legal, and insurable. The mistake is treating it as an afterthought rather than a core part of the planning phase. Talk to your local authority first, then use those facts to brief your builder or architect. When both parties are clear on what is required, the approval process becomes predictable.