Residential Design Series                                         

Roof Conversions

A Roof Conversion can be described as removing part or all of an existing roof, or renovating an existing roof space, to create extra living space.

A Roof Conversion is not a first-floor addition, it is generally smaller and utilizes part or all of the existing roof to create the living space.  Some houses are perfect for roof conversions. Generally, they will have a higher roof pitch are wider than the normal house, this means the ridge will be higher and a substantial cavity already exists. In the inner city roof conversions can be a practical way of creating additional space.

Generally, you will need an experienced carpenter to supervise a roof conversion. Generally speaking councils are sympathetic to roof conversions. There were many roof conversions and additions approved in the past that have been so compromised during the design process that they are hot boxes in summer.  You really need cross ventilation and heavy-duty insulation to create a comfortable living environment.  The councilman neighbours will be sensitive to overlooking so you need to create your space to allow for the sensitive placement of windows.

Houses, which may be suitable for a roof conversion, include, one and two storey terraces, single storey cottages, some semi detached and double fronted bungalows.

Not all houses are suitable for a roof conversion. Some of the questions to be considered are?

1. Is the house heritage listed this is different from being in a conservation area. If the house is heritage listed then your application and planning costs will increase considerably.
2. Do you have an expansive roof cavity? If you have over 2.6 between the apex of the roof and the ceiling joists you can easily renovate to a habitable space. Tighter spaces can still be renovated however they may not qualify as habitable spaces and may need to be listed as storage areas. 
3. Is the existing structure capable of supporting the additional loads? Some cottages and semi-detached houses may require the placement of columns or some underpinning before any work can begin. It may be a good idea to speak to a structural engineer early in the planning process.
4. Where will the stairs go? Does the space you gain compensate you for    what you loose in the placement of the stairs?
5. Will a roof conversation create privacy or overshadowing problems for the neighbours?

Roof Conversions in the inner city tend to be towards the rear of the house. Often the old roof may have been opened or the lid lifted behind the ridge line. This may extend into the rebuilding of the smaller minor roof to create two usable bedrooms, a bathroom and perhaps a study.

 

Roof Conversion Procedure

Building a roof conversion involves the removal of that portion of the roof where the extension is to be located. The position of the new rooms is marked out and the old rafters are cut accordingly. The new beams and floor joists are set out and fixed usually above the existing ceilings, which should remain intact during the building process. 

Once the structural floor is fixed the sheet floor or a temporary plywood floor is fixed.

  The waterproofing of the dwelling is done with a heavy-duty plastic sheeting, which is laid over the new floor. This will remain in place during the building process and will keep the new flooring in reasonable condition.

Once the floor is temporarily waterproofed work begins in earnest to complete the framing and roofing and get the renovation through to lock up.

Lock up is roof on, cladding completed and all doors and windows in place.

Roof Conversions are difficult to build and require expert tradesman and experienced builders.

 Handymen or owner builders should not attempt them.

Roof Conversions have always been a good renovation choice for those who don’t wish to move and who have the required budget. They help fulfill council’s requirements to create or maintain soft landscaping in houses in the inner city. Nevertheless they need to be well planned and you need to consider council and the neighbour’s requirements before a formal development application is submitted. Good Building!