High Water Table and Flood-Prone Homes on the Central Coast

Where the ground or subfloor space is excessively damp or subject to frequent flooding, the National Construction Code requires one of three things on top of the ordinary rules for new work: 50% more subfloor ventilation, the ground sealed with an impervious membrane, or durable or treated subfloor framing. The Code names the cause: areas with high water tables, poor drainage or areas frequently affected by flooding or water inundation.

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What subfloor ventilation for a high water table or flood-prone home on the Central Coast actually involves

Central Coast Council's online mapping tool lets residents and business owners determine if their property is subject to a 1 in 100 chance flood event, or you can contact Council to confirm if your property is within a potential floodplain. A property identified as flood prone has a message placed on its Section 10.7 Planning Certificate, which costs A$73.

When a flood certificate is needed

A Flood Information Certificate provides flood information for a land parcel suitable for a development application or complying development certificate. Council's fee is A$424.55 for the standard certificate, delivered within 15 business days, or A$608.15 for the urgent one, delivered within 3 business days. Neither fee carries GST.

Dark wet soil under a raised timber floor with a still pool of water in a low spot and a brick wall vent at the right — subfloor ventilation for a high water table or flood-prone home, the Central Coast. Illustrative example.

Which part of the Central Coast this applies to

Central Coast Council has floodplain studies that name groundwater or flooding as a local factor for the Woy Woy Peninsula, the Tuggerah Lakes area and the Brisbane Water foreshore. No study read for this site names a street or a house, so use the flood map for your own address. The main page covers the contractor licence.

Check the flood map before choosing a fix, and ask the provider which of the Code's three options the quote assumes.

A grey-framed vent set in a brick wall below white cladding, dry grass and a dirt path in front — subfloor ventilation for a high water table or flood-prone home, the Central Coast. Illustrative example.

Subfloor ventilation costs and rules check