Nov 122012

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.



  266 Responses to “Building Extensions”

Comments (266)
  1. If I already got a extension plan drawn and it expired but I already got the foundation done must I still go and renew the plan again?

  2. Hi

    When drawing up an addition to a house do you need to redraw the entire house plan again with full dimensions and details etc?

  3. Good Day

    Please could you advise me on the following as I cant seem to raise anyone at the City Council.

    I am considering the purchase of a house in Centurion. The current owner has converted one of the two garages into an office. This involved the erection of a brick wall between the two garages plus the replacement of the existing garage door with a window. Also the insertion of a door from the “office” to the interior of the house and of a ceiling.There were no alterations which impact on the external boundaries of the house.

    My concern is should the current owner have had such alterations approved by the City ? When I ask the Estate Agent for proof that the plans for the above alteration have been approved she tells me that such alterations do not need City of Tshwane Approval.

    Thanking you


    • Plans should have been submitted and approved. The estate agent is incorrect! I suggest you contact the City of Tshwane and ask for confirmation in writing. Then you can give the estate agent a copy of the document – and threaten to report him/her to the Estate Agents Board. It’s about time estate agents started operating honestly! In the unlikely event of the council not requiring plans, you will be covered.

  4. Can you please advise of approximate cost of submitting plans for a two bedroom upstairs and downstairs in newlands West durban

  5. Hi,

    How are timber decks treated in terms of the NBRs. Are these seen as minor building work and will formal approval be required in order to install an outside decking area?

  6. Hi I would like to build an outside building that serves as a guest house .what is the correct procedure to do this and how long do authorities usually take to approve the requisitions to do that?

    • You will need to have plans drawn up by a “competent person“, and these will have to be approved before you can build. In addition you will need planning approval from your local authority in terms of a) whether you can build and b) whether the zoning of your property will allow you to run a guest house. Please contact your local authority for information on how long approval is likely to take.

  7. Hi,

    Is it true that you cannot have more than one granny flat on a property?

    We draw up plans to turn our existing double garage into a one bedroom outbuilding and intended to build on top of that – another one bedroom outbuilding. Architect draw the plans, we got a structural engineer to come out – paid both these professionals.

    Went to submit at out municipality and they said you can’t have more than one outbuilding on a property. Why did neither of these professionals tell us this – now we have spent over R10 000 for nothing.

    • It normally depends on local bylaws and zoning. The professionals should have checked these first. Perhaps you can get them to change the plans so that it only one building… though they would have to find a way to link them.

  8. Hi Penny, do I need a engineer’s foundation report and he’s design telling me I must have re-enforcing laid down before poring my concrete. I am adding a 3.5 x 4 metre to my existing bedroom, I had soil tested and the report says my soil is fine for building. My papers from our local council says a dolomite test is not required, so do I need a engineer’s design for my foundation. Is there anyone I can contact on the East Rand that can assist me with the correct information. Please reply to my email.

    • You need approved plans – and if an engineer’s design is required, the request for these will come from the council (that approves your plans). Generally you should include reinforcing even if the soil is okay. Dolomite is a whole different story.

  9. How much will roughly it cost to add an extra bedroom to a house?


  11. Do we need a plan to convert a garage into a granny flat?

  12. Hi,

    How many days on average does a foundation take to cure?
    The area is Sunninghill and I’m not sure of the type of soil in the area and how much difference that makes to the time it takes to cure.
    I want to get some idea as to when the builder should start with the walls being built onto the foundation – someone told me you should wait 28 days as an average.

    • Building usually takes place a couple of days after the concrete has been laid. Concrete hardens before it has cured thoroughly – and it will continue to cure until it reaches full strength – anything from seven to 28 days. The only accurate way to determine how long it will take to reach full strength is by making test cubes to check the strength of the concrete and this will tell you how long it takes for the concrete to reach the required strength. An engineer would do this.

  13. We have a U-shaped house. We would like to install a thatch roof between the 2. Where do we start the hole process. Thanks

  14. Hi
    I have a bond house and I want to extend it, so can you guys please tell me how long does house plan take to be approved by the local council?

  15. Is it possible to draw up and submit building plans at local authorities if you are registered as a Professional Engineering Technologist (Civil, Structural)?

 Leave a Reply


(required but will remain confidential and not be published)