Flat Roof Patios in Subiaco

Subdivision here has produced some genuinely tight sites. A rear survey-strata lot with a courtyard between the house and the boundary is a common Subiaco brief, and the usable dimension is often four metres or less.

At that width an intermediate post is out of the question, so the beam carries the whole span and the outer posts sit hard against the edges of the paving.

A flat roof is the structure that fits. It gains almost no height across the span, which keeps it under the boundary rules and out of the neighbour's light in a way a pitched roof of the same cover cannot manage.

Modern rear additions on old Subiaco cottages vary enormously in how they were built. Rendered brick, framed and clad, or a steel-framed box with a parapet, and each carries a patio load differently.

So the wall gets assessed rather than assumed. Where there is sound masonry or a structural member to reach, a fixed connection works well and keeps the courtyard clear of posts.

Where there is not, or where the wall is mostly glass, the load goes to posts at the wall line instead. It costs two footings and it removes any risk of hanging a roof off something that was never designed for it.

The City of Subiaco protects character and heritage streetscapes across much of the older housing, and the front of a listed cottage is the part that matters most to the assessment.

A patio at the rear, behind a two-storey addition and invisible from the footpath, sits well outside what those controls are protecting. That is the ordinary case and it is generally straightforward.

The exceptions follow the usual pattern. A corner block with two effective frontages, a laneway elevation that reads as public, or an individually listed property will all pull the design into a planning conversation first.

On a small lot the R-Codes bite quickly. Site coverage, the open space required on the block and whether the outdoor living area remains uncovered are the numbers that decide the maximum sensible roof, not the size of the paving.

A house with a two-storey addition has often used a good share of the allowance already. Adding a roof over most of what is left is exactly the move that tips a block past the deemed-to-comply provisions.

Testing that before design saves a redraw. It is a quick check, and it is far better to hear the number at the start than to fall in love with a size that has to shrink.

Where a right of way exists it usually beats carrying material through the house. Long sheets and beams come in from the back, the mess stays outside, and the build runs faster.

Subiaco laneways come with their own obstacles though. Overhead power runs, garages built hard to the lane, bins and the simple fact that a right of way is shared and cannot be blocked all day.

That gets planned rather than discovered. Delivery timing, sheet lengths and where the crew stages material are all worked out against the actual lane, which is why we walk it at the measure.

A building permit is required before construction, because a patio is Class 10a work. The pack is a site plan, elevations, structural engineering for the assessed wind classification and a stormwater design showing disposal on your own land.

Class 10a can be lodged uncertified for the city to assess, or certified with a certificate of design compliance from a registered building surveyor already attached.

Stormwater deserves attention on these lots. There is often very little soft ground left, so the soakwell array may sit under paving or in the only permeable corner of the site, and that can decide where a post can stand.