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 duet stand and I am in the process of doing extensions to my home. I am looking for an agreement document between the neighbour and myself so that he agrees for me to proceed with the construction.


  2. I am planning on building on my property. Going up on the garage and sideways onto a grass bank thats higher than the garage.

    Where do I find my house plans and who do i get to see if the foundations are strong enough, design/approve building plans etc.

    I have no idea where to start.


    • The plans should be lodged with your local authority. Unfortunately, though, it appears (from comments we continually get) that plans go missing quite frequently. In this case you would need to track the previous owner/s down to see if they can help.
      In terms of the National Building Regulations, you need a “competent person” (see link) to draw plans. An architectural designer, architect or draughtsman will be able to tell from the existing plans if the foundations are adequate or not. If you cannot locate plans, I guess they would need you to dig a trench next to the foundations to see how deep they are. You might be able to tell from digging whether they were reinforced with steel or not. The competent person will also need to submit the plans to your local authority, check on building progress and basically sign off the job. So start at your local authority planning office and see if you can locate the plans. You will need to give them your erf number.

  3. Hi there,

    I am going to draw detailed house plans for amendments to be made for
    a family member but I am not an architect. Someone told me that if the
    size of the amendments does not exceed 500sq meters, it does not have
    to be signed off by a registered architect.

    Is this true and if so, please refere me to the legal documents
    stating this.

    Thank you,

    • Hi Crizette,
      I’m afraid that what someone told you is incorrect, the law has changed and now a “Competent Person” has to endorse or draw-up the plans. “Minor Building Work” can be carried out without plans but the local authority must be informed in writing before any work can begin. Go to our “Minor Building Work” page and see some of what is allowed and the requirements. You can go to our other site Ownerbuilding and read more about “Competent Persons”. There is also a page of info on “About the NHBRC” that I think you will find useful.

  4. I am a homeowner in Benoni, currently busy with alterations by a
    “registered” contractor. I urgently need assistance to force the
    contractor to complete alterations to my satisfaction

    • Hi Mr Muller,
      If you want to find out if the contractor is “registered” you can go to the NHBRC website and check their database free of charge here nhbrc-verify-builder. If he is registered then you can lodge a complaint on the same website and they will follow up and take action. If he is not registered then the only recourse that you have is to withold payment until the job is completed to the agreed standard. If you have paid out all the money then unfortunately you have a problem and you will need to take legal action.

  5. Hi Penny,

    Can I build a garage (for three cars) with a little storage and
    external toilet on the boundary (two neighbors affected here, one at
    the back and the other on the side). I also want a floor on top of
    these garages with a storage and a toilet too. on both floors these
    toilets are enclosed with walls and doors. what do i need to do to get
    plans through council like this? I’ve seen this around on other
    properties(building onto boundary line) so it must possible. Area is
    Goodwood, Cape Town


    • Brynn the City of Cape Town has new zoning regulations that came into effect in March 2013, that allow building on boundary lines, with certain restrictions. Generally this means that you no longer require neighbour’s consent. It is no longer relevant where your property is. Size of the plot is the issue. e.g. If your plot is between 350 and 650 sq m in size, then the street boundary building line is 3,5 m and common boundary building lines are 0,0 m for the first 12 m measured perpendicular from the street and 0,0 m for 60% of the total remaining linear distance along all common boundaries around the land unit, and 3 m for the rest (presuming your property is zoned single residential – “The single residential zones are designed to provide locations for predominantly single-family dwelling houses in low- to medium-density neighbourhoods, with a safe and pleasant living environment.”)
      “Where a building is permitted in this zone within 3 m of a common boundary, the height will be limited to 4 m measured from base level to top of roof.”
      “Notwithstanding the provisions in subsection (c)(ii) (which is what I have quoted above), within the first 12 m along a common boundary measured perpendicular from the street boundary line and where a building is not set back from such common boundary, the height is determined in accordance with the ‘Table of floor factor, floor space, height and building lines in Single Residential Zone 1’;”
      There are additional requirements including:
      Window and door placement
      Any portion of a building which contains an external window or door facing onto a common boundary shall:
      (i) be set back a distance of at least 1,5 m away from such boundary; and
      (ii) the portion of building to be set back from the boundary shall include the door or
      window, together with such additional length of wall as is required to make up a total minimum length of 3 m.”
      “Garages, carports and outbuildings
      (i) A garage, carport and outbuildings are permitted within the common boundary building line provided that the garage and carport do not:
      (aa) extend higher than 3,5 m from base level to top of roof;
      (bb) contain more than a double garage façade; and
      (cc) exceed a width of 6,5 m.
      (ii) For land units of 650 m2 and less, a garage or carport is permitted up to 1,5 m from the street boundary provided the garage or carport:
      (aa) is not higher than 3,5 m from base level to top of roof;
      (bb) does not contain more than a double garage façade; and
      (cc) does not exceed a width of 6,5 m.
      In the table, maximum floor space = n/a and maximum height to wall plate = 8 m & to top of roof = 10 m.”
      I hope that helps. If you comply with these, you shouldn’t have any problem getting your plans passed.

  6. I wish to erect an lourve aluminium awning over an existing open
    patio. Do I need to submit plans to the Municpality? I believe it is
    considered a Temporary Attachment and does not require planning
    It is also being fitted by a reputable supplier.
    Regards, Mike

  7. Hi there, we are in the process of buying a property in Jhb where the
    original garage has been knocked thorugh to what was a garden
    Storeroom according to the plans and tiled to be used as an
    office/workshop. The original storeroom was next to the maids’
    quarters and a bathroom was added into the storeroom for the maid. The
    plans state that it was an “Existing Garage converted into storeroom”.
    We wanted a garden cottage to rent out and so we have broken through
    the bathroom into the maid’s quarters to make it en suite and added
    another small bathroom to the old storeroom.We will be adding a
    kitchenette inside the old double garage. What do we have to do in
    terms of building regs? Are we required to submit plans for approval?
    We have not structurally changed any walls (although we will be adding
    a small bathroom window) but simply added another bathroom and will be
    putting the kitchen cabinets etc in (all electrics etc are in place
    and have COC’s).
    Many thanks,
    Kirsty Savin

    • Hi Kirsty,
      The building regulations refer to the usage of any given space in a building not wether the structure has been altered or not. It seems as if the garage/storeroom/maids quarters/garden cottage/bathroom/kitchen has been considerably altered you should have got plans drawn and planning permission before starting to build. You should get a “competent person” to draw up some plans and submit them ASAP. If at any time in the future you would like to sell you will have a problem because what is being sold and the registered plans differ and you could be penalised and delay the sale.

  8. After suffering several broken bones I have decided to extend my
    bathroom to accommodate an easy-access shower. My architect says the
    regulation state that I have to install solar heating but I don’t
    understand why as I am not adding to or changing my existing geyser. I
    am only making more space and modernising the bathroom suite. Is what
    he says true? It seems like a money making plan to me. I switch my
    geyser off every day for at least 12 hours so am not a wasteful user
    of electricity.

    • Hi Audrey,
      I am very sorry to hear of your predicament. But the answer is yes. The new legislation came into effect last year and portions that relate to you read: “In order to contribute to the reduction of greenhouse gases buildings, and extensions to buildings in respect of which plans and specifications are to be drawn and submitted in terms of the Act” and they go on to read under section XA2 “At least 50% (volume fraction) of the annual average hot water heating requirement shall be provided by means other than electrical resistance heating including but not limited to solar heating, heat pumps, heat recovery from other systems or processes and renewable combustible fuel.” Ask your architect what alternative heating methods are available that satisfy the requirements of the act, hopefully he can find an economic alternative for you.

  9. We have just seen a house we are interested in buying but the
    alterations made now have the Bathroom/Toilet window opening into
    another bedroom. I’m sure this is not acceptable. Could you please
    confirm ?
    Many thanks

  10. I would like to find out more about were to make an arch in a load
    bearing wall. How long the span between arches must be and how big an
    arch can be. Were would I find more info about that?

    • Apologies for taking so long getting back to you Gretchen – your query went to Comments and their was a gremlin in our system (we weren’t picking these up)! I have now added some information about arches that might be helpful to you and others who need this information. You will find it HERE.

  11. Question.

    I want to install a carport Between the side of house & Boundry wall.
    The space between house is boundry is 3.5m wide. & length is enought
    to park 2 cars behind each other. There a 3 windows on the side of my
    house facing the boundry. Can I replace the windows (sice they cant
    open) with glass bricks & install the carport here. I understand the
    building inspectors are strict with regards to safety & carports these

    • Hi Ryan,
      You can install a carport on a boundary wall if you have plans and you get them approved by council. You must also get permission from from the relevant neighbours and submit those with your plans as well. You can read more about boundaries here: Boundary Walls & Fences and here Boundary Lines and here Minor Building work. The regulations for windows is determined by what the rooms are used for, if any of them are for a toilet then it is not only light but also ventilation that is needed, you can read more here lighting-and-ventilation

  12. Hello

    Where can I find regulations governing the building of a carport as
    well as enclosing my pool? That is putting a polycarbonate roof on and
    closing the sides with window panes?


    • Hi Ismail,
      The building of the carport will fall under >>minor building work<< (Click the link to read more). But enclosing your pool sounds as though it is more than the minor building law allows so you may well need plans and approval from council. I suggest before you do anything contact your local building inspector and ask their advice.

  13. Good day,

    Could you please let me know what I need to do if my builder has
    already taken 50% of the agreed amount and has hardly done any of the
    work for alterations on a outside building? He keeps making excuses,
    has not pitched in the last two weeks. He does not answer my phone
    calls or messages in the last two days.

    Your advice would sincerely be appreciated.

    • Hi Lizette,
      Is the builder registered with the NHBRC?
      If he is then this is what the NHBRC says: “The housing consumer (home owner) should contact the home builder within three to seven days. The housing consumer can approach the NHBRC if the home builder fails to attend to the problem.”
      If you are not sure if he is registered then you can check here on the NHBRC website.
      If he is not then your only other recourse is to take advice from a lawyer.
      This is why the NHBRC was formed, to protect the public from builders who do not deliver.

  14. I am busy looking at remodeling an old house, and would like to move
    the bathroom and toilet where it has no external walls and hence no
    windows. Is this a problem?

    • Hi Dave,
      Ventilation in toilets and bathrooms is essential. I have seen some toilets and bathrooms that do not have openings to external walls, they have used electric ventilators and extractor fans. The other consideration if you do not have an outside wall, is the waste pipes that connect to the mains sewage or to a containment tank. The health regulations are very strict about these, and I suggest that you contact the Local Authority and ask what they suggest for your situation.

  15. Hi I am in the process of drawing sketches for extending my semi
    detached council house in Durban.I am considering the block and beam
    system for the decking, but want to know what size hollow blocks I can
    use for the exterior walls.

    • Hi Imran,
      The specifications for loadbearing walls will depend on the weight that the wall will have to support. This needs to be calculated and designed by a structural engineer. Your best option is to contact one of the pre-stressed concrete manufacturers in Durban who have the engineers specifications for all their products on hand and will be able to help you. One word of caution, in terms of the new regulations plans have to be drawn up and submitted by a “competent person” please have a look at the link.

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