Aesthetic and Compliant

Polished Concrete Flooring and the NCC  

NCC 2019 Volume 2, Amendment 1

Area of NCC Requirements:

• P2.4.1 – Wet Areas

• Clause 3.8.1.2 – Construction of Wet Areas

The Challenge

Polished and burnished concrete floors are increasingly popular in contemporary residential design, particularly where seamless finishes and integrated heating systems are desired. In this project, the client proposed the use of a polished concrete slab within wet areas in lieu of traditional tiled finishes, with hydronic heating incorporated into the floor build-up.

However, the NCC’s Deemed-to-Satisfy (DTS) provisions for wet areas are largely written around tiled floor systems. As a result, the proposed approach fell outside the prescriptive pathway, raising concerns about waterproofing performance, moisture migration, and long-term durability of the structure.

To proceed, a performance-based pathway was required to demonstrate that the alternative floor finish would still achieve the NCC’s wet area performance intent.

What This Really Means

The NCC does not mandate specific finishes—it mandates outcomes. For wet areas, this means preventing water penetration, protecting structural elements, and maintaining safe and healthy internal conditions.

When a non-traditional finish such as polished concrete is proposed, the key issue becomes whether the floor system, as a whole, can manage moisture as effectively as a DTS-compliant tiled assembly.

The Solution

A performance-based assessment was undertaken to evaluate whether the proposed wet area floor system achieved the intent of Performance Requirement P2.4.1.

The assessment considered:

• How moisture is controlled within the wet area under normal use
• Whether the floor system prevents water migration into the slab and surrounding structure
• The interaction between heating elements, finishes, and waterproofing layers
• Long-term durability and resistance to moisture-related deterioration
• Whether the overall performance is equivalent to, or better than, a conventional tiled wet area

Rather than focusing on surface finish alone, the assessment examined how the complete floor system performs as an integrated assembly.

Why This Matters

The final report confirmed that the proposed wet area design satisfied the NCC’s performance requirements. Despite departing from DTS provisions, the polished concrete floor system was shown to provide appropriate moisture protection and structural safeguarding when assessed through a performance-based lens.

This project highlights how performance solutions allow modern material choices and integrated systems to be used confidently in wet areas—without compromising compliance or long-term building performance.

Considering non-traditional finishes in wet areas? 

Reach out to our team for the solution.