Flat Patios Kalamunda

Very few Kalamunda backyards are flat. The fall might be gentle across a lawn at Gooseberry Hill or severe enough at Lesmurdie that the yard is already terraced into two or three levels.

The roof plane still has to be one clean horizontal line with a controlled fall for water. Getting there means varying post lengths, stepping footings down the grade, and setting out from a level datum instead of the ground.

Sometimes the honest answer is a raised deck under the roof rather than chasing the slope with paving. That decision belongs at design stage, because it changes the structure, the balustrade question and the approval.

Hills ground is a mix of lateritic gravel, clay and granite, with rock that can turn up anywhere from half a metre down to the surface. The neighbour's block is not reliable evidence.

Where rock is shallow the footing design changes rather than the patio. Options include a wider pad, an anchor into sound rock, or shifting the post to ground that cooperates.

It is a difference in method and time more than a fault. What causes trouble is discovering it on install day with a crew standing around, which is exactly what a proper site measure prevents.

Kalamunda sits in designated bushfire prone area on the state map, and that designation reaches structures attached to or close to the house. The bushfire attack level assessed for the site sets the construction standard.

A steel-framed Colorbond patio starts well ahead here, because the frame and the sheet are non-combustible. The risk sits in the gaps, the fixings and whatever is stored or built underneath.

Practical detailing does most of the work. Gutter guard on the patio gutter, gaps closed where embers lodge, non-combustible flashing at the house junction, and a hard think before specifying a timber deck under the roof.

A mature marri has a root plate considerably wider than its canopy, and cutting through structural roots for a footing is how you lose the tree two summers later.

Post positions get moved and beams get resized to work around them. That is nearly always the better trade, because the tree is doing more for the yard than an extra metre of roof would.

Limb drop is the other half of it. Large eucalypts shed branches, and a patio roof directly beneath a heavy overhanging limb is worth talking through honestly before it is built rather than after.

A soakwell only works if the surrounding soil takes water away between storms. Tight clay and lateritic gravel do that slowly, and rock does not do it at all.

So the hills design often looks different to the suburban one. Larger or more numerous wells, dispersal trenches through the more permeable upper layer, or a controlled discharge where the city permits one.

Slope has to be respected in the layout. A soakwell placed uphill of the house, or a discharge running toward a neighbour's block, creates a problem that is much harder to fix later.

The hills run hot in summer. There is no sea breeze worth mentioning until late in the day, and the granite and gravel hold heat well after the sun has come off the yard.

That is the strongest case there is for an insulated panel roof rather than single-skin steel. The foam core slows radiant heat through the sheet and the underside stays cooler to sit under all afternoon.

It buys you a ceiling as well. A finished panel underside takes downlights and a fan cleanly, which on a patio used from October to April is worth more than the saving on sheet.

Blocks along the escarpment at Lesmurdie, Gooseberry Hill and Kalamunda look out over the plain toward the coast. For a lot of people that outlook is the reason they bought the house.

The awkward part is that the view and the worst of the summer sun arrive from the same direction. A roof deep enough to shade a west-facing terrace can also take the top off the outlook from inside.

The usual answer is a shallower roof with a slim edge detail, plus a drop-down blind or a louvre screen on the western side. Shade when you want it, outlook when you do not.