When do you need a contour survey?
You need one before anyone designs on your block:
- You have bought a lot and are designing a new home.
- You are planning an extension, a second storey or a granny flat.
- You are knocking down and rebuilding.
- You are subdividing. The contour survey is the first stage of every subdivision, before the WAPC application.
What do you get from a contour survey?
A plan of the site, delivered to you and to your builder, architect or designer. It shows:
- ground levels across the lot, with contours and spot levels
- the existing house and other structures
- trees, fences, retaining walls and other features
- visible services
- the kerb, verge and crossover at the front of the block
Formats: PDF, DWG, DXF, CSV and hard copy.
How does a contour survey work?
- Ask for a quote. Send us the property address, your contact details, and whether the site will be vacant, the house demolished, or the new work built behind or onto the existing house. We do not quote over the phone, so the online form is the quickest way.
- Get a written quote within 48 hours.
- We survey the site. Once you accept, a surveyor visits and measures the block. Most surveys are done within about two weeks of booking.
- You get the plan. We email it to you and your designer or builder.
Large lots and building envelopes
On a large lot (over 2,500 m²) we survey the building envelope and the ground around it, the access from the road and the services, not the whole lot. That is the part your designer needs levels for.
What a building envelope is. The area inside your lot where the house, and usually any sheds and other buildings, must be built. Your local government sets it through its planning scheme, a local development plan or the conditions of the subdivision that created the lot, and it is sometimes shown on the deposited plan. Councils use envelopes to keep buildings clear of bushfire-prone vegetation, waterways, steep ground and road frontages, and to leave room for effluent disposal.
Why your designer asks for a building envelope sketch. The envelope is defined from the boundaries, for example 30 m from the front and 20 m from each side, and nothing marks it on the ground. Our plan shows it in its true position against the title boundaries, with the contours inside it, so the design fits and the council can see that it complies. Building outside it means applying to change it, which takes time and can be refused.
Not sure whether your lot has one? Ask the council or the developer, or send us the lot details with your quote request and we will check. If there is no envelope, we survey a 50 m × 50 m area where you intend to build.
What else do people ask about contour surveys?
Is a contour survey the same as a feature survey?
Yes. A contour survey and a feature survey are the same survey: one plan with the ground levels and contours together with everything on the block and the verge. We call it a contour and feature survey; builders and designers sometimes call it a site survey or a detail survey.
Do I need a contour survey for an extension?
Usually, yes. Your designer needs the levels of the existing house and the ground around it so the new work fits. If you are renovating inside as well, you may also need an internal survey. Our guide Planning an extension? explains the choice.
Should the survey be done before demolition?
It depends on your local government, so check with them before the house comes down. Tell us the house is coming down when you ask for a quote, because it changes how much detail the survey needs.
Will the levels be on AHD?
Your choice at booking. Levels on the Australian Height Datum (AHD) are an option; otherwise they are on an assumed site datum. Choose AHD if your designer or local government needs levels that line up with other plans, such as floor levels, sewer depths or height limits. In some suburbs your local government makes AHD levels mandatory; we'll tell you when we quote.
Does the plan show the sewer?
It shows the visible services, such as inspection openings, meters and pits. Where the sewer runs along or near your block, the plan can also show the sewer line and junction, so your designer can check the new house will drain. Ask us if your designer needs more, such as sewer depths.
Why do I need a building envelope sketch?
Because on a large lot the council only approves a house built inside the building envelope, and the envelope is defined from the boundaries, not marked on the ground. The sketch shows where it really is, with the levels inside it, so the design fits and the application passes. See the section on large lots and building envelopes above.
Areas: We work across all of Perth, north to Guilderton, east to Northam and Brookton, and through the South West as far as Bridgetown and Augusta. See South West surveys.