In short
Our structural engineers cover the Inner North: Braddon, Reid, Ainslie, Turner, O'Connor, Lyneham, Dickson, Downer, Hackett, Watson and Campbell, at the same prices as the rest of Canberra. A structural inspection and report is from $1,090 + GST ($1,199 inc GST). The local fact worth knowing first: in the Garden City heritage precincts, an application to demolish an identified house must include a professional structural assessment.
Structural engineer Inner North: local facts
- Oldest homes
- Braddon's 1921–22 cottages, the first Garden City precinct; most of Reid built 1926–27
- Heritage precincts
- Braddon, Reid, three in Ainslie, the Tocumwal houses in O'Connor and a Northbourne public housing sample
- Rock
- Canberra Formation shale, where weathered zones up to 30 m deep are common
- Wet ground
- Slow-draining clay fans below Mount Ainslie under Ainslie, Braddon and Reid; seepage recorded at Ainslie
- Mr Fluffy
- 107 homes on the official list across the district; 2 still on the register (Hackett and Watson)
- Dwellings in 2021
- 42.6% apartments, 39.2% separate houses, 18.0% semi-detached or townhouses
Do the Garden City heritage precincts change what an engineer does?
Yes, whenever an owner wants to demolish, dig a basement or make a big structural change. Reid alone has two looks: Federal Capital Commission designs in rendered masonry with prominent gables, and Department of the Interior designs in red face brick.
| Precinct | Suburb | What it protects |
|---|---|---|
| Braddon Housing Precinct | Braddon | 1921–22; "the first expression of the Garden City concept in Canberra" |
| Reid Housing Precinct | Reid | Mostly 1926–27; rendered masonry and red-brick designs |
| Corroboree Park | Ainslie | 1925–27 tradesmen's housing |
| Wakefield Gardens | Ainslie | 1925–29 houses, plus a 1947 Beaufort steel house |
| Alt Crescent | Ainslie | A Garden City precinct |
| Tocumwal Housing Precinct | O'Connor | Post-war relocated prefab cottages |
| Northbourne Housing Precinct Representative Sample | Dickson, Lyneham | A sample of Northbourne public housing |
From the ACT Heritage Register. Check your block there or on ACTmapi before you plan work.
In the Garden City precincts, total demolition of an identified house is allowed only in exceptional cases, such as a house "so structurally unsound as to be beyond reasonable economic repair", and the application "must include a professional structural assessment in support of demolition". Reid allows a basement only "where the structural stability of the dwelling is assured". The Tocumwal precinct allows demolition only if a house is "structurally unsound and beyond economical repair". Our engineering for older and heritage homes covers these assessments.
What about Tocumwal and Monocrete houses?
Both were fast answers to the post-war housing shortage, and both sit on footings quite unlike a modern slab.
Tocumwal houses are US Army Air Corps huts moved from Tocumwal, in New South Wales, and rebuilt in weatherboard and fibro. O'Connor's precinct is "the most intact example", and a few stand in Ainslie. Accounts describe them going up "without concrete foundations", on "a double row of bricks laid directly onto the ground in a shallow trench".
Monocrete houses are bolt-together precast concrete panels: in 1946, 100 were tendered for Turner and O'Connor, built "on brick piers and surrounding brick footing". Shallow brick footings move as the clay under them wets and dries, so we read the whole frame, not just one crack. A structural inspection and report is $1,090 + GST ($1,199 inc GST).
Why do Inner North houses crack and move?
Two local reasons: deeply weathered shale under most of the district, and wet, slow-draining clay on the slopes below Mount Ainslie.
Most suburbs here sit on Canberra Formation shale. Geoscience Australia's notes on Canberra's geology say "deeply weathered zones, although generally not deeper than 30 m, are common" in this rock. Drilling on the eastern edge of the city centre found weathering "up to 80 m deep" along a fault zone. Rock can be near the surface on one part of a block and metres down on another.
Ainslie, Braddon and Reid also sit partly on fans of soil washed down Mount Ainslie's footslopes, which the ACT's soil mapping flags for widespread poor drainage and seasonal waterlogging. The geology notes record seepage problems at Ainslie. Clay that stays wet in winter and dries in summer moves the footings above it.
A cracks and footing movement report ($1,090 + GST ($1,199 inc GST)) finds the cause. If you have one question, such as whether a planned basement is practical, a site visit with a letter of advice is $650 + GST ($715 inc GST).
Was the Inner North hit by the 2018 flood?
Yes. On 25 February 2018, 60 mm of rain fell in one hour at Sullivans Creek, and apartments and homes flooded in O'Connor. The ACT Government lists it (Lyneham, 2018) as one of Canberra's two major 1% AEP floods, meaning a flood with a 1% chance of happening in any year.
Its flood maps on ACTmapi cover major channels and creeks, but "might miss places where water may be stopped or redirected", so we never label a block safe or at risk. After water has been through a house or basement, a structural inspection checks the footings, floors and walls.
Which rules apply to building work here?
ACT rules apply: development approval from the Territory Planning Authority unless the work is exempt, then building approval from a licensed certifier. Two local points matter most.
- Heritage. Work that would breach the Heritage Act 2004 loses its development approval exemption, and demolishing a registered place likely needs a development approval. The ACT Heritage Council can advise.
- Asbestos. Any house built or started before 1985 needs an asbestos removal control plan with its building approval. The Mr Fluffy list has 107 Inner North homes (Hackett 29, Watson 16, Ainslie 16, O'Connor 15), and two, in Hackett and Watson, remain on the register. See our guide to older homes and asbestos.
What does an Inner North job cost?
The same as anywhere else in Canberra, with the price fixed before we start.
| Situation | Service | From |
|---|---|---|
| Cracks in a cottage, sticking doors | Cracks & footing movement | $1,090 + GST ($1,199 inc GST) |
| One question: a basement idea, a sagging floor | Site visit with a letter of advice | $650 + GST ($715 inc GST) |
| Opening up a load-bearing wall (needs building approval) | Wall removal & beam design | $890 + GST ($979 inc GST) |
| Buying a Tocumwal, Monocrete or 1920s house | Pre-purchase structural inspection | $790 + GST ($869 inc GST) |
| Demolition or a major change in a precinct | Older & heritage homes | Fixed quote |
With 42.6% of the district's homes in apartments in 2021, we also write condition and defect reports for apartment buildings. We're engineers only: we don't sell or recommend the repair, so our advice isn't tied to a sale.
Nearby, our Inner South page covers the rest of Canberra's 1920s precincts, Gungahlin sits on the same Canberra Formation shale, and the February 2018 storm also flooded a basement in Bruce, in Belconnen.
