What is a contour survey?

A contour survey is a measured drawing of your land that shows height variations across the block using contour lines. Each line represents a consistent elevation, usually marked at intervals of 0.5 or 1 metre, allowing you to see the slope direction and steepness at a glance.

Before designing a home on a sloping block, a contour survey gives your builder and architect the information they need to position the house, plan cut-and-fill earthworks, and determine retaining wall requirements. On steep sites, it reveals where split-level construction makes sense and where foundation design must account for significant level changes. The survey also shows drainage patterns and helps identify problem areas like low points where water may collect.

Contour surveys vary in detail. A basic survey marks key height points; a detailed one includes spot levels, trees, drainage lines, and existing structures. The level of detail depends on block size and slope complexity. For a small, relatively flat block, a simple survey may be adequate. For a large block with uneven terrain, detailed contours become essential for practical construction planning.

This document becomes a reference throughout design and building. Your builder uses it to set out the footprint, plan foundation depths, and manage site works. Without it, you risk costly design changes once excavation begins, or structural problems from inadequate foundation planning on sloping land. Builders experienced with sloping blocks routinely request contour surveys early in the project.