Reducing risk in tendering large concrete floors


It’s hard to see what the issues could be with tendering large concrete floors. They are simple to estimate and a commodity item, as long as you get a competitive concrete and placing and finishing rate.

However, they are a big ticket item. A 40MPa 165mm-thick floor with armoured joints and an applied silicate is going to cost upwards of $80/sq m. The trouble is, when they go wrong they cost a similar amount to remove.

Add to that the time involved, disruption, consequential losses, holds on payments, and damage to reputation.

Conslab is one of New Zealand’s leading concrete flooring contractors, undertaking everything from discussing options with developers, design, constructing and maintaining floors, right through to polishing or applying epoxy coatings.

The company sees a large range of specifications and tenders, and a considerable number of contractors exposed to serious risk.

There is risk of failure from designs and specifications through to the methodology and interaction between the floor and racking, and forklift specifications for floor coverings.

Interestingly, flatness specifications are often overlooked. Conslab sees specifications from around the world, and it pays to understand what they mean and the methodology required to achieve them.

Issues can also result from restraints by engineers tying floors to walls, poor joint layouts, incompatible strength-to-water cement ratios, and calls for no pumping.

During winter there are subgrades that are still wet and don’t meet design strength specifications. The remedial process is time consuming and costly, often resulting in a complete redesign of the floor.

Ultimately, the quality of the floor is dictated by the tradesmen on the tools and the care they take.

Specifications don’t equal quality. They just provide a measure of success or failure. For businesses, the floor is often a critical part of their operations, and good advice is key.