Removing a wall: what makes it load-bearing, and what it takes to take one out

"Can we just knock that wall out?" is one of the first questions we hear on almost every renovation walk-through. Sometimes the answer is a straightforward yes. Often it is "yes, but", and the "but" is a beam, two posts, new footings, an engineer's design and an approval. Occasionally it is "not without changing a lot more than the wall". The difference is not visible from the room. It depends on what the wall is doing for the rest of the house, and that is the part worth understanding before you plan around an open-plan layout.

How loads travel through a house

Every house has a load path: the route that weight takes from the roof down to the ground. Roof tiles or sheeting sit on battens, which sit on rafters or trusses. Those bear on the top plates of certain walls. Ceiling joists and any floor above do the same. The walls carry that weight down through their studs to the floor structure or slab, and from there into the footings and the soil.

A wall that sits in that path is load-bearing. Take it out without replacing what it does, and the load has nowhere to go except into whatever is nearest: a ceiling that sags, a floor above that bounces or cracks, door frames that jam, or in the worst case a structural failure.

There is a second job a wall can do that has nothing to do with weight. Some internal walls are bracing walls. Under AS 1684, the standard for residential timber framing, a house needs enough bracing to resist wind pushing it sideways (racking). That bracing is designed as a system, spread through specific walls in each direction. A wall can carry no roof load at all and still be part of the bracing that keeps the house square in a storm. Remove it, and the bracing has to be made up somewhere else.

We cover how the framing standards work in more depth in our article on carpentry and structural integrity.

Signs a wall may be load-bearing, and why you should not decide yourself

There are clues: walls running at right angles to ceiling joists, walls near the middle of the house, walls directly above a beam or wall on a lower floor, walls carrying a thicker top plate. But each of those has exceptions. Truss roofs often span from outer wall to outer wall and bear on nothing in between, while older pitched roofs (common in Sydney houses built before trusses became standard) often rely on internal walls to support struts, underpurlins and ceiling joists. Renovations over the decades may have moved loads around in ways that are not obvious. And bracing walls look like every other wall once they are lined.

So we are deliberately not giving a self-assessment checklist here. The only reliable answer comes from someone getting into the roof space and sub-floor, looking at how the structure actually sits, and where there is any doubt, a structural engineer. That inspection costs very little compared with getting it wrong.

What removing a load-bearing wall actually involves

When a wall that carries load comes out, its job has to be handed to something else. In practice that usually means:

• An engineer's design. The replacement beam is sized for the actual loads it will carry and the span it has to cover. Timber and engineered timber beams are designed to AS 1720.1; steel beams to AS 4100. The design also covers the connections at each end, which matter as much as the beam itself.
• Posts, and something solid under them. A beam concentrates load that used to be spread along a whole wall into two points, one at each end. Those points need posts, and the posts need to sit on something that can take a concentrated load. On a slab that may mean cutting in a new pad footing; on a suspended timber floor it often means new piers and footings below.
• Temporary propping. Before the wall comes out, the structure above is supported on temporary props so nothing moves while the beam goes in.
• Replacing lost bracing. If the wall was part of the bracing system, the engineer or designer specifies where that bracing resistance is replaced, for example by upgrading other walls with structural sheathing.
• Making good. Ceilings, floors and wall junctions have to be patched and finished, and a flush (concealed) beam usually costs more than a dropped beam that sits below the ceiling line.

There is also what is inside the wall. Electrical circuits, plumbing, gas lines and ducts are often routed through internal walls, and relocating them is licensed work in its own right. In older homes, there may be asbestos.

Asbestos in older homes

SafeWork NSW advises that buildings built or renovated before 1990 may contain asbestos, including in fibro wall and ceiling sheeting. Removing a wall in an older house can disturb it. Removal of friable asbestos, or of 10 square metres or more of non-friable asbestos, must be done by a licensed asbestos removalist, and SafeWork NSW recommends using a licensed removalist for any amount. If your home is in that age bracket, have suspect materials tested before demolition, not during it.

Approvals in NSW

This is where many people are caught out. NSW allows some internal renovation work to proceed as exempt development, without council or certifier approval, under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 (the Codes SEPP). But the exempt pathway for minor internal alterations, in Subdivision 26 of the Codes SEPP, excludes work that affects the load-bearing capacity of the building or changes the configuration of a room by removing a wall. In other words, taking out a structural wall to open up a floor plan is generally not exempt.

That leaves two usual pathways:

• Complying development certificate (CDC), issued by a council or a registered certifier, where the work fits the relevant code's standards; or
• Development application (DA) to council, followed by a construction certificate, where it does not.

Which applies depends on the property, its zoning, heritage status and the scope of work, so it is worth confirming early. Heritage items and conservation areas have additional limits.

If you live in a strata scheme, there is another layer. Structural walls are usually common property, not part of your lot. Under the Strata Schemes Management Act 2015, changes to common property generally need a special resolution of the owners corporation (section 108), and the simpler "minor renovations" pathway in section 110 specifically excludes work involving structural changes. Approval from the owners corporation comes before council or certifier approval, not after. Our article on renovating a strata apartment covers this in more detail.

Where it commonly goes wrong

• Assuming instead of checking. "It's an internal wall" is not the same as "it carries nothing".
• Undersized or unengineered beams. A beam that looks big enough, sized by eye rather than by calculation.
• Point loads with nowhere to go. A correctly sized beam sitting on posts that bear on a slab edge or a timber floor that was never designed for concentrated loads.
• Forgotten bracing. The wall carried no weight, but it was holding the house square.
• No approval. Work done without a CDC or DA can create problems at sale, with insurance, and with the owners corporation in strata.
• Asbestos discovered mid-demolition, after it has already been disturbed.

Questions to ask before a wall comes out

1. Has someone inspected the roof space and sub-floor to confirm what the wall is carrying?
2. Is the wall part of the house's bracing system, and if so, where will that bracing be replaced?
3. Who is designing the beam, posts and footings, and will there be engineering drawings?
4. What approval pathway applies: CDC or DA? If strata, has the owners corporation approved it by special resolution?
5. What services run through the wall, and who is relocating them?
6. If the house was built before 1990, has it been tested for asbestos?
7. Will the beam be flush or dropped, and how will the ceiling and floor be made good?

How we approach it

We treat any wall removal as structural work from the start, not a demolition job. We inspect the roof space and sub-floor before we quote, bring in a structural engineer where the wall carries load or bracing, and price the beam, posts, footings and make-good from the engineer's design rather than a guess. We confirm the approval pathway and, in strata, the owners corporation approval before any work starts. On site, the propping, beam installation and connections are inspected and photographed before the ceiling is closed in, the same hold-point approach we use for waterproofing and framing. If something unexpected turns up when the wall is opened, we stop and talk it through, as described in our article on what happens when a renovation uncovers a hidden defect.

Opening up a wall is often part of a larger kitchen or living-area project; see our guide to kitchen renovation approvals and trades for how the pieces fit together.

If you are planning to open up your home, get in touch and we will tell you plainly what the wall is doing and what it would take to move it.

Sources

• State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, NSW Legislation
• Remedial building work: Codes SEPP fact sheet, NSW Department of Planning and Environment
• Strata renovation rules, NSW Government
• Strata Schemes Management Act 2015, NSW Legislation
• Asbestos, SafeWork NSW
• AS 1684.2:2021 Residential timber-framed construction, Standards Australia

This article is general information, not structural engineering or planning advice for your property. Whether a wall is load-bearing, and what approval its removal needs, depends on the building and the site, so confirm it with a structural engineer, your certifier or council, and in strata, your owners corporation. Full website disclaimer