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HardieSmart® ZeroLot Wall System

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Build Right to the Boundary, Build Independently

Zero-lot developments, where two dwellings share a common boundary line with no setback, solve a genuine land-use problem in established suburbs. But they create a construction sequencing problem: if both dwellings are built with a shared wall, one owner’s build depends on the other’s. Sell one lot before the other is finished, and things get complicated fast.

The HardieSmart® ZeroLot Wall System solves the sequencing problem as much as the fire compliance problem. It’s a dual boundary wall solution; each dwelling gets its own independent wall built to the zero-lot line rather than a single shared party wall. That means each dwelling in the development can be constructed independently, sold independently and occupied independently, without waiting on the neighbouring building. FRL 60/60/60, CSIRO and BRANZ assessed up to 2.45 m² more internal space per dwelling than a standard 230 mm brick veneer wall over every 10 linear metres.

60/60/60

Fire Resistance Level (minutes)

2.45m²

Extra internal space per dwelling per 10m wall length

CSIRO

Assessed by CSIRO Division of Building Construction & BRANZ

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Technical Specifications

Design guide

Fire Resistance Level

60/60/60 minutes (standard) — for higher FRL requirements, consult James Hardie Engineering Solutions

Suitable building class

Class 1 and Class 10a timber-framed buildings

Frame configuration

Independent 90mm timber frame per dwelling, built to the zero-lot boundary line

Insulation

HardieFire™ mineral wool insulation within stud bays

External cladding

James Hardie™ or Scyon® external cladding, 6mm or greater thickness

Internal lining

Villaboard™ lining (refer to design guide for lining configuration options)

Assessment

CSIRO Division of Building Construction and Engineering · BRANZ (New Zealand)

Bracing capacity

Typically 4 kN/m for plain timber framing and standard fixing, up to 6–10 kN/m with alternative fixings and 12mm anchor rods

Applications

Fully detached row housing · dual and single zero-lot boundary conditions

NCC reference

NCC Vol. 2 Section 3.7.1.8 — boundary walls to maintain FRL 60/60/60 minutes

Design flexibility

Stud spacing may be increased to 600mm centres with reduced load-bearing capacity (3.4 kN/stud), insulation cutting required at this spacing

How the System Is Built

Each dwelling in a ZeroLot development gets its own single 90mm timber-framed wall, built directly to the boundary line. The frame is insulated with HardieFire™ mineral wool insulation within the stud bays, clad externally with James Hardie™ fibre cement cladding, and lined internally with Villaboard™ lining. Because each wall is independent, not a shared party wall, each dwelling’s construction, certification and occupation timeline is entirely decoupled from the neighbouring lot.
This is the specific design intent behind ZeroLot: it’s for dual and single zero-lot boundary conditions where each side of the boundary is built and owned separately, as opposed to the intertenancy system, which is designed for a shared wall inside a single building.

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The Business Case, Not Just the Compliance Case

Independent construction sequencing

Because each dwelling has its own wall rather than a shared party wall, one dwelling can be completed, sold and occupied while the neighbouring lot is still under construction or hasn't started.

Improved cash flow

Decoupled construction timing means a developer isn't waiting on the slowest-selling or slowest-building lot to close out sales and settlements on the others. For a multi-lot zero-lot development, this can materially change the project's cash flow profile.

More usable floor space than brick veneer

At 2.45 m² of extra internal space per dwelling over every 10 linear metres of wall compared to a standard 230 mm brick-veneer wall, the compact ZeroLot system profile translates directly into saleable or usable floor area, a meaningful yield difference across a full development.

Fully detached title outcomes

Because each wall belongs entirely to one dwelling, ZeroLot supports fully detached construction and title outcomes, as opposed to shared-wall party arrangements that can complicate strata or Torrens title structuring on smaller infill sites.

Featured Projects with HardieSmart® ZeroLot Wall System

Bacchus Marsh Grammar Woodlea Project

Mernda Ambulance Station Cladding Project

The Wickham Duplex Residential Project

Frequently Asked Questions

What is the difference between the ZeroLot and Intertenancy wall systems?
ZeroLot is a dual boundary wall system; each dwelling gets its own independent wall built to the zero-lot boundary line, meaning the two sides are structurally and legally separate. Intertenancy is a shared wall system, a single twin-frame wall assembly that separates two sole occupancy units within the same building or development, typically used in row housing and attached dwellings. ZeroLot supports fully detached construction and independent build timing; Intertenancy is for attached dwellings sharing a common separating wall.
In some cases, yes. James Hardie notes that confirmation in writing, in the form of a statutory declaration from the registered owner of the adjoining premises, may be required to demonstrate compliance, depending on council, state or other regulations that apply to the specific development. The designer or specifier must confirm the applicable requirements for the project location before finalising the ZeroLot specification.
Yes. Stud spacing may be increased to 600mm centres, though this reduces the loadbearing capacity to 3.4 kN per stud. At 600mm centres, on-site cutting of HardieFire™ insulation will be required, as the standard insulation pack sizes are optimised for 45mm studs at standard spacing. Confirm the structural implications of increased spacing with your engineer before specifying.
The HardieSmart® system family, including ZeroLot, is assessed for use across a range of Class 1 and 10a applications, including bushfire-prone areas, but the specific bushfire attack level (BAL) compliance should be confirmed against the current ZeroLot Design Guide and the site’s BAL rating. For projects with a confirmed BAL requirement in addition to the boundary FRL requirement, contact our team for the relevant documentation.