Flat Patios Serpentine-Jarrahdale

Mundijong is the administrative centre and it is growing in its own right, with newer housing appearing around the older townsite core.

Serpentine is smaller and sits out toward the national park and the falls, with a mix of town lots and rural residential land around it.

Jarrahdale is up in the forest against the scarp. Cardup, Oakford, Oldbury, Keysbrook, Hopeland and Karrakup fill in between as rural and rural residential country, measured in hectares rather than square metres.

Getting materials to the build is the shared complication. Long gravel driveways, farm gates and turning circles decide the maximum sheet and beam length that can physically reach the house, and that gets measured on the first visit rather than assumed.

The Jarrahdale townsite grew around timber milling from the 1870s, and a good deal of that history is still standing. The shire maintains a heritage list, and parts of the townsite are treated as a precinct rather than as individual properties.

For a rear patio that is usually workable. What the controls protect is largely the streetscape, and a low structure behind the house is well outside that view.

The process changes though. Where a property is listed, the design, the fixing method and sometimes the colour are settled with the shire before a building permit is lodged, rather than in parallel with it.

Almost every rural block out here already has a shed, and the shed is usually the second biggest thing on the property. Ignoring it produces a patio that looks like it landed by accident.

So the reference point is often the outbuilding rather than the house. Taking the roof colour, the gutter profile and the trim from an existing Colorbond shed makes the two structures read as a set.

Position does the rest. Lining the patio up with the shed, or squaring it to the same axis, turns two separate objects into something that looks planned even when they were built twenty years apart.

In the suburbs a post position is decided by a fence, a path or an air conditioning unit. On a rural block none of that applies, and the post can go wherever the structure is most efficient.

That turns span into an economic decision instead of a constraint. A deeper beam carrying further costs more in steel and less in footings, and an extra post reverses it, so the two get priced against each other.

Wind pulls the other way out here. Open paddock offers almost no shielding, so the assessed rating can come back higher than a built-up suburb would give you, and that pushes the sizing back up.

Size deserves a second thought as well. A roof that looks modest against ten hectares can be a very large structure in its own right, and beyond a point it starts attracting planning questions the same building on a suburban lot never would.

A good deal of this shire appears on the state bushfire prone areas map, particularly toward the scarp and the forest. It is an address check rather than a suburb assumption.

Where the mapping applies, an assessment sets a bushfire attack level, and a Class 10a structure close to the dwelling is generally captured by the same construction requirements as the house.

In practice that shapes materials and details rather than the shape of the roof. Steel roofing and steel structure are already non-combustible, so the attention goes to gaps, openings, any enclosing elements and anything timber in the design.

A patio is Class 10a work, so a building permit from the Shire of Serpentine-Jarrahdale is required before construction, with a site plan, elevations, structural engineering and a stormwater design.

The planning side is where rural properties differ from the estates. Rural and rural residential zones run under the local planning scheme rather than the R-Codes, with their own setbacks, site coverage and outbuilding provisions.

That last one is worth checking on a large freestanding structure. A big roof standing on its own posts can be assessed against outbuilding provisions rather than as an attached patio, which changes the setbacks it has to meet.

Unsewered lots add one more step. Where a septic system and leach drains sit in the yard, they get located before any footing position is confirmed, because you cannot dig through one or roof over the disposal area.