Converting a shed to a house

Shed Houses and Building Law. This is a must read

We regularly come across people who want to convert their existing shed into shed houses.  Sometimes they have already been converted into a shed houses but there is no building approval. But what many don’t realise, is that there is a lot more to converting a shed to a house than just changing the appearance and fitting it out with a sweet interior.

Changing the classification of an existing Class 10 Building – or Shed – to a Class 1 Dwelling, or part of a dwelling, provides significant challenges that should be carefully examined before considering the viability of the project.

In order to help you better plan your conversion project, we’ve put together the following list of the most significant issues. This is not an exhaustive list however, so keep in mind there will be other elements to consider:

Siting

1.) The siting requirements for sheds and dwellings are different in most Queensland Local Government areas. In most cases, dwellings have to be located 1500 mm from side and rear boundaries and six metres from the front boundary. Siting requirements should be checked with your local government.

2.) Where a building is too close to a boundary or boundaries, there are many possible solutions varying from modifications to the building or the installation of walls with a fire rating. However, before these matters can be considered, the local government’s siting requirements will need to be addressed so you should discuss your renovation proposal with them.

Floor Slab Height

1.) The floor slab height of most existing sheds is normally not high enough to achieve the minimum habitable floor height level. It is essential to comply with this standard, and as each local government determines the minimum floor slab height for habitable rooms, you should check requirement details with them.

2.) If the required floor height is not to standard, it would be necessary to either raise the existing floor slab by concreting over it, or to lower the surrounding ground surface.

a.) Concreting over the floor slab would require lifting the complete building frame to the new level. This would effectively require the removal and replacement of the building.
b.) Lowering the surrounding ground surface would require a civil engineer’s design to be prepared. The design would have to provide a solution that stops storm water from a 1:100 year storm entering the building. This solution would require substantial excavation and drainage while ensuring the existing building is not undermined. Consideration will also have to be given to the impact of this solution on the existing sanitary drainage system and on adjoining properties.

Waterproofing Under the Slab

A slab laid on ground that is to be used for habitable purposes, must have a waterproof membrane installed underneath to stop rising damp. A regular shed slab is not required to have this waterproofing element. It is necessary to establish beyond doubt whether the existing slab was provided with this waterproof membrane. This could be achieved with a core sample or via other means, however is most likely that this membrane will not be present. If this is the case, we are not aware of any acceptable system that allows this membrane to be retrofitted.

Waterproofing Wet Areas

It is necessary to provide waterproofing to all wet areas e.g. bathrooms, toilets, and laundries. The waterproofing is a membrane that is installed before other floor coverings such as tiles etc. It is necessary to establish beyond doubt that a waterproofing membrane has been installed. This could be achieved by removing the floor and wall coverings in several locations. It is most likely that this membrane has not been provided. In that case, it would be necessary to remove all floor and wall coverings in the wet areas, and to install the waterproofing membrane before replacing the floor and wall covering.

Structural Adequacy

Sheds most likely have been built with a lower design criteria than dwelling structures, which is reflective of their importance. Dwellings are designed to importance level 2 whereas, in the past, many sheds were only designed to importance level 1 or less. Therefore, is necessary to establish whether the existing building has been designed according to the criteria for a dwelling in its location. To do this, it will be necessary to obtain the original design drawings and have them reviewed by a registered professional engineer. The engineer would have to provide certification that the existing building meets all the necessary design parameters for a building in this location.

Energy Efficiency

The building would have to conform to the current energy efficiency provisions of the building law. This would require, at the least, thermal insulation throughout the external shell of the building and additional window shading. There will most likely be other matters related to energy efficiency that will also have to be addressed.

The viability of changing a sheds to shed houses or part of a house has to be considered on a case-by-case basis by the owner. We strongly recommend that, before any commitment is made to change the classification of a shed to a dwelling, that the owner make themselves aware of the complete impact and cost of this decision.

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I am a Director of Development Certification Pty Ltd and have been a Building Surveyor since 1989. I have a bachelor degree in building surveying and I am a qualified carpenter. I have been in the construction industry since 1981. I have a real passion for the building certification profession as I believe building certifiers are the general practitioners of the construction industry. Our role is not only to know building law and apply it, our role includes assisting in the development of the knowledge of all in the industry by sharing our knowledge and experience.