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Intumescent – Things to consider as the client

Posted on 15th April 2021

By Simon Heath

Intumescent Paint

We thought it would be helpful to put together a blog, with a view to running through some of the more frequently asked questions or queries with regards to intumescent paint application. During the pre-construction process we utilise a pre-commencement checklist to start conversations about the below and much more.

Intumescent Paint Application & Bolt Preparation

In line with the manufacturer guidance, when applying a water based intumescent paint to structural steel work, it is important to prepare any steel that has been galvanised. This process includes the degreasing and priming of any galvanised steel, and leaves the substrate in a condition ready to receive treatment.

Protection of surrounding areas

Due to the installation nature of intumescent paint, and the usual site installation environment. It isn’t uncommon to experience some drift of paint particles during the installation process. It worth considering whether the surrounding surfaces need protecting, or whether any drift will be removed by a following trades, thus making protection not a requirement.

A ‘carding’ methodology can be used to minimise the risk of overspray onto adjacent surfaces, such as concrete soffit or block work wall. But unfortunately carding will not take away the risk of drift due to climate conditions.

Attachments to your steelwork

During the project build it is likely that various items maybe attached to the treated steelwork.

It is worth considering this and the below set of drawings, as it is likely that this work will need to be interfaced with other trades, and may affect programme.

Finish

It’s worth considering how the product will look once the installation has been handed over. The NBS clarifies what to expect from a basic installation of intumescent paint.

• 440 BASIC FINISH

• Reasonably smooth and even. Orange peel, other texture, minor runs and similar minor defects are acceptable.

• 450 NORMAL DECORATIVE FINISH

• Good standard of cosmetic finish generally, when viewed from a distance of 5 m or more. Minor orange peel or other texture is acceptable.

• 460 HIGH DECORATIVE FINISH

• High standard of evenness, smoothness and gloss when viewed from a distance of 2 m or more.