Site analysis
Reading a Perth block properly
Everything expensive that goes wrong in a garden was visible on site before the work started. This is the phase where a professional finds it: levels, soil, sun, wind, water, services, and an honest audit of what is already there.
You end up with
A measured base plan and a constraints-and-opportunities plan for your block.
What you produce in this phase
Measured base plan
Produce a scaled base plan of your property showing boundaries, house footprint, doors and windows, paths, existing structures, downpipes, taps, meter, and every tree over two metres. Note the scale and the date.
Levels survey
Set a permanent datum point on your block and record spot levels on a grid across the site, plus at every door threshold, boundary corner, and existing drain. Mark them on your base plan.
Soil report
Record results for each test area on your block: soil type, pH, water repellency (the water-drop test), depth to any hard layer, and drainage rate. Note which areas will need the most amendment.
Sun and wind analysis
Overlay onto your base plan: summer and winter sun paths, the areas in shade at 9am / noon / 3pm, the hottest surfaces on site, the prevailing summer sea breeze direction, and the winter storm direction.
Services plan
Lodge a Before You Dig Australia enquiry for your address, then mark every located service on your base plan: sewer line and access chambers, water main and meter, power (overhead and underground), gas, comms, and every existing retic line and valve you can find.
Existing garden audit
List every existing element on your block — each significant plant, paved area, structure, edge, and the retic system. For each: condition, remaining life, cost to keep versus cost to replace, and a verdict of KEEP, RELOCATE, REPLACE or REMOVE, with the reason.
Constraints and opportunities plan
Produce a single annotated overlay on your base plan marking every constraint (services, easements, setbacks, shade, root zones, poor drainage, hot walls, overlooking, access limits) and every opportunity (good views, sheltered corners, existing mature planting, level areas, sun in winter).
Lessons
- 01
Measuring up: a base plan without paying a surveyor
Triangulation, running dimensions and a long tape will get you a base plan accurate enough to build from. Learn the method, and learn when the block is complicated enough that a feature survey is cheaper than the mistakes.
⏱ 90 minIntermediate📐 Makes: Measured base plan - 02
Levels, falls and datum: shooting levels cheaply and accurately
Every drainage decision, every step, every retaining wall and every paved surface depends on levels. Water hose level, string line, laser level and dumpy — what each costs, what each is good for, and how to set a datum you can return to.
⏱ 90 minIntermediate📐 Makes: Levels survey - 03
Perth soils: identifying Bassendean, Spearwood and Karrakatta on your block
The Swan Coastal Plain is a set of ancient dune systems, and which one you are on changes your plant list, your irrigation design and your soil budget. Grey sand, yellow sand, or brown sand over limestone — find out which you have and what it means.
⏱ 45 minFoundation - 04
Soil testing: pH, water repellency, depth and nutrition
Perth sand is hydrophobic, nutrient-poor and often alkaline near limestone. Four cheap tests tell you what you are dealing with, and they determine thousands of dollars of decisions later in the project.
⏱ 60 minFoundation📐 Makes: Soil report - 05
Sun, shade and the Fremantle Doctor: aspect analysis south of the equator
North-facing gets the sun here, west-facing walls will cook you and your plants, and the afternoon sea breeze is a design element you can plan for. Map the sun through the year and the wind through the day.
⏱ 60 minFoundation📐 Makes: Sun and wind analysis - 06
Water on site: drainage, soakwells, low spots and roof runoff
Find out where every litre goes before you change a single level. Roof areas, downpipes, existing soakwells, surface falls, the puddle that never dries, and whether your neighbour's stormwater is your problem.
⏱ 60 minIntermediate - 07
Locating services: Before You Dig, sewer, water, power, gas and existing retic
In WA you have a legal obligation under the Work Health and Safety Act 2020 to identify underground services before excavating, and you can be held liable for the damage. The free lodgement takes a day; hitting a gas main takes considerably longer.
⏱ 45 minIntermediate📐 Makes: Services plan - 08
Auditing an existing garden: keep, kill, or salvage
Renovating is harder than starting from bare sand, because you must judge what is worth keeping. A structured audit of every plant, surface, structure and system — with a verdict and a reason for each.
⏱ 90 minIntermediate📐 Makes: Existing garden audit - 09
Tree assessment, retention and when you need an arborist
Mature trees are the most valuable thing on most blocks and the easiest to kill accidentally. Root zones, structural roots, council tree protection, and the works that quietly finish off a tree two years later.
⏱ 45 minIntermediate - 10
The constraints and opportunities plan
Everything from this phase, on one drawing. This is the document a designer works from, and it is the reason a professional design fits its site while an amateur one fights it.
⏱ 90 minIntermediate📐 Makes: Constraints and opportunities plan