Building Extensions

Planning House Extensions

Whether you are building a new home or planning house extensions to an existing home, you are going to need building approval from your local authority. Even if you are simply opening up a wall or partitioning a room by erecting a new internal wall, most councils will insist on working drawings.

house extension
A self contained flatlet has been added on over an existing double garage and a patio created on the flat concrete roof over the front entrance hall.

They won’t worry about issues like matching materials or style, but they will consider all the elements that relate to building codes and building standards.

Extension Options

There are various ways that you can extend an existing house. For instance you can go up and create a second storey or opt for a more straightforward lateral extension. If the pitch of your roof is sufficient, you might be able to convert this into an attic room. Alternatively you could add a separate freestanding structure with a link to your existing house.

Having said that your local authority isn’t going to be bothered with style, this is an element that is essential if the extension is going to look good. Materials should also match or look as though they have been chosen carefully. This means that if yours is a facebrick dwelling, the extension should be built using the same finish facebrick. If it is plastered and painted, it is best to match the paint colour. This isn’t always as easy as it might seem, since paint colors fade and from time to time manufacturers change their specifications.

Planning for a Building Extension

Sometimes, but not always, people do plan for future extensions. This makes it a lot easier when it comes to adding on a room or converting space. As an example, where a future door is planned, building in a lintel at this point, and enclosing the door area with straight joints will make it easier to knock out the brickwork at a later stage. The fact that the bricks aren’t bonded beneath the lintel won’t be an issue, because the lintel will support those above.

Even so, you will need to be sure that the extension is correctly executed, with the correct foundations (unless of course you are going up, in which case you will need to have existing foundations that can take the weight of the new building extension), and where brick or block walls meet, these will need to be bonded, or joined in such a way that cracking will not affect the structure.

Types of House Extensions

These include:

  • building a core house and then adding to it later according to existing plans
  • converting a garage into extra living space
  • converting an attic into habitable space
  • constructing rooms in a roof where there is no existing attic
  • adding or converting a cellar
  • adding a conservatory, sunroom or pool room, usually with glass
In all instances it is essential to ensure that your new house extension complies with building standards.

Develop a Core House

If you are building and you don’t have the means to build the size house you believe you need, an excellent solution is to build over a period of time. Thoughtfully designed, it will never look incomplete.

Below are three drawings that show how a core house (coloured yellow) may be added to over time.House extension 1

In the first drawing, you can see that it is a simple, compact two-bedroomed home. Both bedrooms share a bathroom and they are both the same size. Each room has built-in cupboards and there is a laundry cupboard in the passage outside the bathroom. The living area is open plan, with a bar counter “dividing” the living space.






House extension 2In the second drawing, the kitchen has been extended, in such a way that existing plumbing is used, even though the sink changes position. An exterior door is added, linking to a courtyard with a washing line, and to a double garage. One section of the garage incorporates a storeroom, adjacent to a loo with a basin, accessible from the courtyard.  The main bedroom is also included in this phase, although it could, of course, be built on later, since it is at the opposite side of the house. An en suite bathroom and more substantial cupboards are also included in the new plan.















In the third drawing, an open-plan lounge-dining room has been added (blue), along with a new entrance way and a guest loo. A swimming pool has also been included on the plan, though this could also be a separate phase.House extension 3

Convert a Garage

This can be a very convenient and reasonably easy way to extend a house, although local authorities are usually strict in terms of upgrading the existing finishes. For instance you may need to have a ceiling installed, and lighting and ventilation might need to be upgraded.

Add a Sunroom, Pool Room or Conservatory

There are companies that specialize in glazed structure (or one where a polycarbonate material is used) that fit this category, though you can also have something designed and custom built.

Go into the Roof

Many older homes were built with attics that were intended to be used for storage. You might need to add windows and insulate the walls and ceilings to make the space habitable.

If there isn’t an existing attic, and the roof is high pitched enough, you might consider building a room in the roof space. The basic concept is very similar to converting an attic, although structural alterations will be considerably more complex. If the pitch is not sufficient, you will have to extend the gable ends and increase the pitch of the roof.

In both instances you will probably have to add stairways that are easy to use.

In South Africa and other hot-climate countries, the roof space (and attic) in a house can become unbearably hot, so it is essential to pay attention to insulation.

Go Underground

Cellars are surprisingly uncommon in South Africa, but they are sometimes included in the design of a house, and may be added at a later stage providing the foundation walls are high enough. Generally it is easier to add a cellar where the house has been constructed on a slope.

Just remember that for a cellar to be converted into a habitable space (even if only as a playroom), it must be totally dry (there must be a damp-proof membrane between the brickwork and the soil beneath ground level) and have sufficient light and ventilation. Usually this will entail installing artificial ventilation and electric lighting.



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  1. Can anyone please point me in the right direction?

    I am buying a house. I am planning on adding a second story, not on top, but above the current house… I am planning this by building a steel frame supported on steel beams, which will be set in concrete…

    How do I go about getting this approved? And do I do this at the local municipality offices?

    It won’t be used as a living space, but more like a workshop for my electronic developments…

    • Hi Jan, From what you are saying you will need an engineers report to accompany the plans that will have to be submitted to your local council before construction starts. The submission can be done by yourself or your architect/draughts person. You will also have to apply for a permit/exemption to have an industrial business operating in a residential area.

  2. My neighbors would like to extend their house, obstructing my ocean view. At what point will they require neighborhood permission. Their alteration will grossly affect my property value.

    • Hi Brett, The law states that you are entitled to the full enjoyment of your property. So a neighbour is not entitled to obstruct your view. He may do this if he has an agreement with you. I have no idea why you would agree to this as the value of your property without a view would fall dramatically. The council is obliged to protect your rights and you can object to any build that has an adverse effect on these. If you do not get any joy from them there is the PAJA that you have recourse to, read more here:

  3. Hi
    I want to build 3 flats on my property 30m2 each.
    Will I beable to do this?
    If possible must they join onto the exciting property?
    I was thinking of possibly putting a high pitched roof on for the bedroom, what are your thoughts?

    Your help will be appreciated

    • I presume you mean existing property Robin? However obviously any additions will be on the existing property – so maybe you mean the existing house?
      It may be possible for you to build three additional units on your property, but unlikely. It depends on the size of the property and the zoning. Municipalities are very strict when it comes to what are classed as additional dwellings and more often than not they will limit people to a second dwelling only.

  4. hi thr…i want to extend my existin house also go up and build seperate guest architect insists that im going to have a problem with coverage as i can only cover 50 percent of my property …others differ though..what wil b correct

    • It depends on the zone your property is in. All local authorities have their own zoning regs, so you need to get hold of your local council/municipality and see what your zoning is. This will specify coverage. Note that there are also bylaws relating to separate dwellings on a property.

  5. Hi. What does building regulations say about minimum dimension for a double garage? My garage is 6m long wall to wall measuring from outside.

  6. Hi

    Is it necessary to notify the council / submitted plans, if I am planing to install a built-in bay window?
    I have been told that the installation includes the following:
    1. Removal of existing window, widening of opening and replacement with lintels.
    2. Installation of the bay window with floor and specially designed roof.

    I was also told that the existing roof will not be effected by this installation.

    Your assistance with this is highly appreciated.

    • The best approach would be to ask the council if they need plans. They might because lintels have to be replaced. On the other hand they might not!

  7. Hi

    I want to build an apartment on top of a double garage, do i need plans for it, and how much will it cost more or less.

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