A three-storey commercial building in Whakatū, Nelson, has cut 500,000 kilograms of CO2-equivalent emissions compared with a concrete-and-steel building on a tight urban site where fire codes typically rule structural timber out. That is according to Jeremy Smith and Andrew Irving of Irving Smith Architects, the firm behind the WallÉ-X typology and its 2022 predecessor, the Forsyth Barr building.
Wood Central understands that WallÉ-X carries nearly 2,000 square metres of commercial floor area, saving around 250 kilograms of CO2-equivalent per square metre, with LVL posts and beams sitting alongside CLT floors and stairs, inside fire-resistant pre-cast concrete sidewalls, and a concrete ground-floor slab.
A single diagonal K-brace runs through the building from the ground up, changing material as it rises. At ground level outside the Wakatu Lane entry, the brace is solid steel. On the first floor, it becomes a steel plate sandwiched between two LVL timber boards. By the second floor, it is pure LVL with no steel at all — the heaviest material at the bottom, where lateral forces are largest, the lightest at the top, where they are smallest.
Smith said the design question throughout had been where timber could replace concrete and steel on the site. “We’re trying to make a timber building. We just have to use concrete in some places so we can build on the site,” Smith said.
What makes the typology unusual is the top-floor wall set back about 1.2 metres from the concrete balustrades on each side boundary. The setback satisfies fire-code maintenance access requirements for the top-floor cladding, allows construction in timber, and doubles as outdoor space for the top-floor tenancy.
Irving said the geometry handled the fire-code requirement without reading as a compliance move. “This doesn’t look like we’re cheating the fire code. It just looks like a deck, and there’s a lot to be said for putting less building on the north-west corner,” Irving said.
Smith and Irving argue that fire ratings are the central reason structural timber tends to cluster on larger, campus-style sites. Internal ratings affect timber sizing through char rating, connections, and finishes, whilst external ratings, designed to prevent fire spread between properties, force timber buildings into separations that tight sites cannot afford.
Smith said the city’s question was whether architecture had to abandon fine grain to use timber. “Most cities are made up of small tenancies. So, does that mean the small fine grain of smaller cities has to be merged together to make big sites so we can build in timber?” Smith said.
WallÉ-X’s saving of 250 kilograms of CO2-equivalent per square metre is more than three times that of its 2022 predecessor, the Forsyth Barr building, which saved around 70 kilograms per square metre. The first WallÉ trimmed about 50,000 kilograms of CO2-equivalent across its floor area, whilst WallÉ-X has trimmed around 500,000 kilograms across nearly 2,000 square metres.
It comes as Wood Central reported a global wave of mass timber commercial construction through 2025 and 2026, from Denmark’s TRÆ tower to a series of CLT projects across London. Each of those buildings sits on larger sites with the fire-code separations WallÉ-X has been designed to do without.
A diamond-patterned bronze screen, perforated to filter light, covers the first floor and about half the second-floor façade. The second floor carries an extended “shark’s mouth” eave and a recessed verandah in the north-western corner, both sheltered by the top-floor setback above.
About six tonnes of steel fixings sit above the second floor, connecting the timber truss roof to the pre-cast concrete sidewalls. “There’s about six tonnes of steel above us, grabbing hold of the concrete walls,” Irving said.
The ground floor sits about a metre above street level to anticipate a one-in-100-year flood event, with the level change handled by recessed stairs and a ramp running the width of the building. The floor overhang shelters both the ramp and the entry stairs.
Smith said the practice intended to scale the typology across the urban grain rather than amalgamate sites to make timber stack up. “We’re not going to amalgamate sites to build in timber. We’re saying we are going to come up with a typology that allows us to build in timber but use concrete and steel to facilitate location,” Smith said.
