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. I have a 3bedroom kitchen,dining and a lounge house and I want to extend up with a main bedroom insuite,a study and a living room.i need to know the estimated cost

  2. Good Day

    Can you please explain this to me

    I want to build a garage next to my existing house. I have contacted the architect to update the drawing and submit for approval. Now i apparently also need engineering services for structural design of the garage. Why are they necessary because the the municipality people come out to view the foundation before it is started. Please help me understand why its necessary to have engineers for the structural design? Is the person who builds not going to build according to the architects design?

    • You wouldn’t normally need an engineer to draw a garage plan. You need to press the architect to give you a proper explanation.

  3. Hi Guys,

    We looking at demolishing our out-building, which is totally separate to the main house and building a granny cottage. Can anyone give me some advice on the process to follow in terms of plans, approval, etc. I live in the Durban area.


    • All the information you need to know is on this website. In a nutshell you need to get a competent person to draw up plans and then submit to council for approval.

  4. hi

    i need to complain on someone that wanted me to rent their outbuilding but they don”t have any plans done for it and the building is already up with extentions. i was very upset to know how the building went up without a plan.

    please help on who i can call and complain to

    • Contact the local authority and give them a complaint in writing. Then follow it up to make sure that they do something about this.

  5. What would a fair price be for plans to be drawn up for about a 80sqm extension to an existing dwelling in the Highway area of Durban?


  6. I want to add an entire second floor as a seperate residence. What planning etc do I require?

    • Hi John, There are a number of things, your local by-laws will say how many dwelling units you are allowed, and the area coverage you are allowed on your erf. All by-laws are different for each area. If that is OK then you will have to get an engineers report to state that the existing foundations are strong enough to carry the extra weight of another story. He could also make recommendations as to how to underpin the foundations to strengthen them, this depends on your local council if they find this acceptable. Then you will have to get an architect, or a “competent” registered person, to draw up the plans and you will have to submit them for approval before you start building.

  7. Im still paying my bond house I need to build rooms outside what route must I takd?
    And if I want to extend the house how and where I get a permit and title deeds?

    • You need to have plans drawn up and approved by the local authority before you can build on. If you have bond, the back will be holding the title deeds, so you can ask them if you can look at them (they won’t release them to you, but there’s no reason why they shouldn’t allow you to see them to check whatever it is you want to check) or go to the Deeds Office in Pretoria and ask to see them.

  8. We bought a house in a complex that is not access controlled or part of a body corp. We would like to extend the current building up and over to raise the exiting garage as well. Can you give me any info on the foundation requirements when converting single to double story?

    • There is substantial information on foundations on this website. But since you want to extend the building and build up, you are going to need approved plans and a “competent person” to draw these up and take responsibility for the build. That person (or an engineer) will specify your foundation requirements. In any case, if you are going to increase the height of an existing building, an engineer will have to determine how this is done – e.g. by underpinning.

    • i do house plans
      contact me 072 196 7129

  9. halo penny
    I am from Williston and I have submit a plan in October 2013and again in November 2014 because there was some faults tell me ,is it not the municipality responsibility to have there own building inspector .because the reason why my plan can be approve is because the civil engineers is the ones that approve the plans know and I feel that it is not write because here were a health inspector that approve the building plans but since the new municipal manager come he sad that that guy can do it any more no tell me I and now gatvol for it I want to start building and they cant get so far and approve my plan can I start build or will it be not a write move to make please tell me what to do .or tell me can a building inspector come and knock my house down if I have start without a plan

    • Dirri, It is difficult to advise you without knowing what the municipality’s objections to your plans are. They certainly have no legal right to hold you up for such a long time without telling you what the problems are. To answer your questions. Yes the municipality must have building inspectors to be able administrate the National Building Regulations. There are times when a civil engineer has to involved, in which case the municipality will ask the owner of the property to ensure certain things in the plans are up to specific specifications. Health inspectors do not have the authority to pass plans, though they may be called on to check health-related issues. There may be a civil engineer in the municipality’s planning department who is responsible for approving plans, but that is no excuse for a hold-up of 20 months. If you go ahead and build without approved plans, the municipality won’t do the required inspections, and they could tell you to demolish the house at a later stage. They can also halt the building construction because you don’t have plans. I would give them a letter in writing demanding that they given you notice IN WRITING of what they require from you to get your plans passed.

  10. Could you please advise me how much would it cost to build a standard room by a size of a garage that could fit only one car

  11. Hi

    Kindly advice lm planning to build 3 back rooms and the wall as my house is the corner.

    kindly advice what rout must l take?


    • The first step is to have plans drawn up. You need to get a competent person to do this (see link). This person will then submit the plans to your local authority. Once they are approved, you can build.

  12. We have built a deck, The deck does not touch or tie into the existing building. This i am told is free standing? and no plans are need if it is above 1m from the ground level. Is this so as i cannot find it in the building regulations. I also cannot find a definition of free standing according to building law. I cannot find any legislation regarding decks, local or National law.
    Please help

    • Grant, the National Building Regulations do not cover decks. They are not even mentioned in the section of Part A of SANS 10400 that deals with minor building work. A freestanding deck is, as you correctly say, one that is not attached to a building. You need to check what your local authority by-laws say about decks – if anything. The council will also be able to advise whether plans are required or not (ultimately it’s their call – and requirements may be different in different parts of the country). You are more likely to need plans the higher off the ground the deck is. This would be for safety reasons.

  13. Hi, I want to build a double story house, on the boundary wall. The plan drawer told me that the upper level must be 3m away form the boundary wall and that this is a new law.

    Is this true? This will mean the upper level will be reduces from 80sm to 40sm which doesn’t make any sense.

    I understand neighbors don’t want people looking into their property, but what If I don’t have any windows in the back that face them?

    As you can see this is a small house, and I cant loose half the space upstairs. please advise urgently?


  14. hi

    I just bought a house in the new development houses in Cosmo City, Johannesburg. I would like to extend but I need to know before I get a plan and approval, what must be the distance between the new building and my wall fence which is adjacent to the street (Front) and between the wall fence which is adjacent to my neighbour (Sides)


  15. Hi,
    I’m trying to find out if I need building plans for close a porch in.
    It has a floor, roof structure, load bearing pillars and lintels holding the roof up.
    all I want to do is move the window out and close the one wall and put the door in the other closed up wall.
    Everything stays under the existing roof, the closed in walls, window and door will be under the existing 3 lintel of the porch.

    Can anyone provide some advice if I need building plans?
    I can’t find anything specific in the NBR that explains this scenario.

    • Generally if an alteration doesn’t affect load bearing walls then you don’t need plans. But at the end of the day the local authority makes this decision, and if you decide to sell one day and the change is not on your plans then you might be required to get an addendum to the plans – and they might fine you. So it’s really best to ask them whether or not it is necessary.

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