Guide: Standards & Tolerances 2019

Table of Content

What is the WA Guide to Standards and Tolerances?

This guide, published by the WA Department of Mines, Industry Regulation and Safety (DMIRS), outlines acceptable workmanship for residential buildings where detailed specs are missing in contracts or regulations. It bridges the gap between legal standards (like the NCC) and real-world expectations for building quality.

Who Should Use This Guide?

  • Homeowners – to assess if construction meets reasonable standards.

  • Builders and Contractors – to verify compliance and avoid disputes.

  • Building Inspectors – as a benchmark to identify defects.

Authority & Legal Standing

While not legally binding like the Building Code of Australia (BCA) or the NCC, this Guide is used by DMIRS and the State Administrative Tribunal to assess complaints. It is advisory, meaning its standards apply when no specific contract or regulation does.

How Tolerances Are Measured

  • Horizontal and vertical deviations are measured with spirit levels or straight edges over defined lengths.

  • Tolerances must not be proportioned to shorter or longer sections (e.g. a 4mm deviation limit over 2m applies equally to 1m).

  • Cracks are evaluated by width and location (more on this in Section 10).

Visual Inspection Guidelines

Surfaces must be inspected from a normal viewing position (1.5m–2.0m away under natural light). Minor blemishes not visible from this position are generally not considered defects.

Remedial Work & Responsibilities

  • Remedial work must match the surrounding materials in appearance and performance.

  • Builders are responsible for damage caused during their work, but not damage caused by homeowners or unrelated third parties.

  • Structural repairs may require permits or engineering certification.

Renovations & Recycled Materials

  • Standards apply only to work included in the renovation contract.

  • Recycled or second-hand materials must be declared in the contract and proven fit for purpose.

Building Maintenance Obligations

Homeowners must:

  • Maintain drainage to prevent foundation movement.

  • Clean steel and timber surfaces as per guidelines.

  • Notify builders promptly of visible issues. Failure to do so may void builder responsibility.

Key Construction Standards

Siteworks

  • Paving cracks >1.5mm = defect

  • Poor slope away from house = defect

  • Fence damage during construction = builder liable

Slabs & Footings

  • Levelness deviation over 2m: >10mm = defect

  • Crack width >2mm in slabs = defect

  • Cracks categorized from 0 (negligible) to 4 (severe)

Masonry

  • Horizontal misalignment >15mm = defect

  • Plumb deviation >10mm per 3m height = defect

  • Mortar cracks >0.5mm or missing mortar = defect

Framing

  • Stud plumb deviation >10mm per 2.7m = defect

  • Joist or bearer gaps >3mm without packers = defect

Cladding & Roofing

  • Visible leaks = defect

  • Cladding not aligned or bowed >5mm over 2m = defect

Finishes

  • Cracks in render >0.2–0.6mm (depending on soil class) = defect

  • Peeling paint, inconsistent finish = defect

Timber Flooring

  • Gaps in boards >2mm = defect

  • Excessive squeaking or springiness = defect

Electrical, Pools & Misc.

  • Pools must align with plans to within ±20mm

  • Cracked tiles, loose fittings = defect

Common Defect Criteria & Tolerance Tables

  • Wall Cracks:

    • <1mm = minor (no action)

    • 1–5mm = monitor/repair (Category 2)

    • 5–15mm = moderate (Category 3, repair required)

    • 15mm = severe (Category 4, urgent structural repair)

  • Render Cracks:

    • Vertical: >0.2mm–0.6mm = defect depending on soil class

    • Step cracks around windows/doors: >1mm–3mm = defect

  • Concrete Floors:

    • Spalling, honeycombing, blowholes = defect within 12 months

  • Tiling:

    • Lippage >2mm, grout gaps >1.5mm = defect

Dispute Resolution in WA

If you believe your builder’s work is defective:

  1. Refer to your contract and see if the defect is covered.

  2. Compare against this Guide’s tolerance limits.

  3. If unresolved, lodge a complaint with DMIRS under the Building Services (Complaint Resolution and Administration) Act 2011.

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FAQ

1. Is the Guide to Standards and Tolerances legally enforceable?
No, the guide itself is not a legally binding document. However, it is widely used by dispute resolution bodies like DMIRS and the State Administrative Tribunal (SAT) in WA to assess whether building work meets acceptable industry standards—especially when contracts or regulations are silent on a specific issue.

2. What kinds of cracks are considered defects?
Generally, cracks less than 1 mm wide are not considered defects. Cracks between 1–5 mm may require monitoring or minor repairs, while cracks over 5 mm are considered moderate to severe and may require structural assessment.

3. How are tolerances measured during an inspection?
Tolerances are measured using straight edges, levels, laser tools, or plumb lines. The guide defines maximum allowable deviations (e.g., 10 mm over a 2 m span for floor levelness).

4. Does the guide apply to renovations?
Yes, the guide applies to contracted renovation works, especially where new work integrates with old. It also outlines specific conditions for using recycled or second-hand materials in renovations.

5. Who is responsible for post-construction maintenance?
Homeowners are responsible for maintaining site drainage, keeping termite barriers intact, and performing general upkeep. Builders cannot be held liable for damage due to poor maintenance.

6. What if the contract says something different from this guide?
If a contract or regulation (e.g., NCC) specifies a stricter or different standard, those terms take precedence. The guide acts as a fallback when no other detail exists.

7. Are minor surface imperfections considered defects?
No. Marks, paint inconsistencies, or blemishes not visible from 1.5–2 meters under natural light are generally not considered defects.

8. Can homeowners be held responsible for certain defects?
Yes. If the homeowner or a third party causes damage (e.g., landscaper damaging weep holes), the builder is not liable. Also, if the homeowner fails to report issues promptly, that may void their claim.

9. What’s the most common reason a claim gets rejected?
Either the issue falls within acceptable tolerances or the homeowner altered the building/site in a way that compromised performance (e.g., changed drainage, added soil against walls, etc.).

10. How do I resolve a building defect dispute in WA?
Start by notifying your builder in writing. If not resolved, lodge a complaint with DMIRS under the Building Services (Complaint Resolution and Administration) Act 2011. Include photo evidence, dates, and references from the guide where possible.