What to budget for the structural engineering on a renovation or extension in Adelaide, from opening up a wall to adding a room.
What Decides the Cost of Engineering a Renovation?
On a renovation, the engineering fee follows the existing house more than the new work. Opening up one wall in a recent brick-veneer home is a short design; opening three walls in a double-brick villa with a hip roof, ceiling joists running the wrong way and footings nobody has looked at since 1925 is a much longer one. The things that move it most:
- How many openings, and how wide. Several openings are designed together as one job, so reworking a floor plan at once costs less than doing it wall by wall.
- What the wall was carrying. Ceiling joists, roof struts, an upper floor or a point load from a girder truss each change the beam and the posts under it.
- Where the load goes next. A new post usually needs a pad footing, and on reactive clay that footing is designed for the site class, not guessed.
- The condition of what is already there. Cracked masonry, undersized lintels or a previous owner's alterations are found on the inspection and allowed for, not discovered by the builder.
Whatever the scope, ANS aims to give you a higher standard of engineering than you would expect at the price, and the fee is fixed in writing before any work starts. The design also specifies the temporary propping the builder needs while the wall comes out.
Large Openings, Portal Frames and Blade Walls
A wide opening, such as a stacker door or a fully open kitchen and living area, can remove the bracing an internal or external wall used to provide. A portal frame or blade wall puts that sideways stiffness back, so the house does not rack in wind. It is designed alongside the beams and priced as part of the same job.
What Does an Extension Need?
An extension usually needs a footing design, and often beams where the new part joins the old. The new footing has to work with the existing one beside it, so the engineer looks at both. A second-storey addition adds the question of whether the existing walls and footings can carry the extra load, which is where a structural report or a site inspection comes in.
Do I Need a Soil Test for an Extension?
Most extensions with new footings need a soil test, because the footing has to be designed for the site class under AS 2870, the Australian Standard for residential footings. If a current soil report for the address already exists, it may be usable, and you are told before a new one is ordered. Soil tests are carried out by specialist contractors that ANS briefs and coordinates.
Structural Reports and Inspections
A structural report gives a written engineering opinion on a defined question, such as cracking, a sagging floor or whether a wall is load-bearing, and is priced on the question it has to answer. A site inspection is a shorter visit to check something specific during the work. Each answers one question well; neither is a full building inspection.
Not sure what your job needs? Read do I need a structural engineer for a renovation and removing a load-bearing wall.
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This page is general information about renovation engineering in Adelaide, not a quote. Every job is priced for its own site and scope, and you get a fixed fee in writing before any work starts.