Flat Patios Gosnells

Thornlie, Huntingdale and Langford are the established middle. Mostly 1970s and 80s brick and tile on lots around 700 square metres, with fascias that carry a patio comfortably and yards deep enough to use properly.

Southern River and the newer pockets nearby are a different product. Smaller lots, an alfresco already built under the main roof, and a design guideline sitting on the title in a lot of cases.

Martin and Orange Grove sit apart from both. Semi-rural blocks against the foothills, bigger and treed, with parts of that eastern edge appearing on the bushfire prone map.

Guildford Formation clay takes up water in winter and gives it back in summer, and it changes volume doing it. The movement is concentrated near the surface, which is exactly where a shallow footing lives.

So the site classification matters more than most people realise. A reactive site carries a different footing design, and the engineer sizes it against that classification rather than a standard table.

The practical consequence is simple. A patio quoted off a plan without anyone looking at the ground is a guess, and in this council area the guess is usually low.

Sand takes stormwater almost as fast as you can deliver it. Clay does not, and a soakwell in clay fills up and then waits, which is useless when the next front comes through two days later.

The array here is sized against the soil, not just the roof area. That can mean more wells, greater total capacity, or a wider shallower layout using the more permeable upper soil.

Overflow gets designed rather than assumed. On flat Gosnells blocks the water leaving a full soakwell heads for the lowest ground, and that should not be the back of the house.

The 1970s lots through Thornlie and Huntingdale are generous, and the first instinct is to roof as much as possible. That is usually the wrong call.

Winter sun matters in Perth more than people account for. A patio that runs too far out from a north-facing wall takes the low July sun off the back rooms of the house for three months of the year.

So the depth gets chosen deliberately. Far enough out to shade the summer sun and cover the table, short enough that winter light still reaches the glass behind it.

A freestanding roof set further out in the yard solves the same problem another way. It leaves a strip of open sky between the house and the patio, so the low winter light still gets to the back windows.

Gosnells sits well east of the coast and the afternoon sea breeze has lost most of its bite by the time it arrives. Summer runs hotter here and stays hotter into the evening.

Single-skin Colorbond over a paved area is a radiator in that climate. An insulated panel roof with a foam core cuts the radiant heat coming through, and the underside stays far cooler to sit under.

Colour and air movement do the rest. A lighter solar-reflective finish absorbs less, and a fan mounted into a panel ceiling shifts the still air that makes a January evening unpleasant.

A patio is Class 10a work under the National Construction Code, so the City of Gosnells needs a building permit before construction starts.

The application takes a site plan, elevations, structural engineering for the assessed wind classification and a stormwater design that matches the soil. It can go in uncertified for assessment, or certified with a certificate of design compliance attached.

Development approval is separate and depends on the R-Codes. Boundary setbacks, remaining open space and whether the required outdoor living area stays uncovered are the provisions that come up most on the smaller lots.

Semi-rural Martin and Orange Grove addresses need the bushfire question answered as well. Where the property is mapped as bushfire prone, the construction standard follows the assessed rating.

Plenty of Thornlie and Huntingdale yards have a pool in them, and the barrier around it is the thing a new patio can quietly break.

Posts, beams, seats and anything else sitting inside the non-climbable zone beside a barrier can create a foothold. That is a compliance failure no matter how good the patio looks.

So the barrier goes on the site plan alongside the patio. Agreeing the post positions against the fence line before the footings are dug beats moving something later that is set in concrete.