Building-In Under Highset Homes

In Queensland, it has been a widespread practice for homeowners to build rooms in the subfloor area of high-set homes.

Whilst this may be done correctly by a licensed builder in many cases this work has been undertaken by the homeowner, without legislated building approval and with the work not carried out to any recognised standard. If you are contemplating buying a highset home that has been built in under you should make sure that the following have been addressed.

 

1. Floor Raise

Has the floor been raised so that it is a minimum of 150mm above the exterior finished ground level? If this is not done the area is likely to flood during heavy rain.

NOTE: A pre-purchase inspection will only report evidence of water ingress, drainage issues, etc. and does not report on the adequacy of design, compliance issues or building approvals.

2. Moisture Barrier

Has the floor and the base of the walls had a moisture barrier installed. If this is not done the area may be affected by conditions of dampness which promote the development of mould and timber pests such as fungal decay and termites.

NOTE: A pre-purchase building inspection cannot confirm what was installed during construction. This is deemed to have been undertaken by a builder and certified by a Building Certifier at the time of construction. The pre-purchase inspection will report on dampness and excessive moisture if symptoms exist but cannot identify future damp problems in the absence of symptoms.

3. Termite Barrier

Has the termite barrier and/or inspection zone been relocated to the ground level from its original position at the ant caps at the tops of the stumps or the strip barriers at the top of subfloor walls? Termites must be prevented from entering the home via a concealed path and it is the purpose of the so-called "termite barrier" to make termite ingress visible to a regular inspection process.

A physical (non-chemical) barrier does not prevent termites entering a home. A concrete floor slab can only form part of a termite barrier if it is constructed to the required standard without any unprotected penetrations such as metal piers, water pipes, etc. It is often difficult to achieve this when building in under a highset because of the pre-existing footings and piers. In most cases, a chemical barrier is essential when the sub-floor is built in.

NOTE: The pre-purchase inspection will identify any bridging of barriers and other conditions conducive to termite ingress.

4. Compliance with BCA

Has the head height, ventilation, glazing, etc. requirements of the Building Code of Australia been complied with?

NOTE: A pre-purchase inspection will only report evidence of defects and does not report on the adequacy of design, compliance issues or building approvals.

5. Locally Approved and Certified

Has the building work been approved by the local authority and certified?  

NOTE: Many local authorities approved the subfloor area to be used as a utility area (laundry, garage etc.) but not as habitable rooms. You should make sure via searches of local authority records that the construction in the sub-floor has been approved and certified. Some unfortunate people have bought a 5 bedroom 2 bathroom home only to end up with a 3 bedroom one bathroom home.


A pre-purchase building inspection will only report evidence of defects and does not report on compliance issues or building approvals.

 

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