Paints and Wall Coverings

Normally, the surface finish and the material to which it is applied both contribute to the overall flame-spread performance. Most surface coatings such as paint and wallpaper are usually less than 1mm thick and will not contribute significantly to the overall rating.

This is why the NBCC assigns the same flame-spread and smoke developed rating to common materials such as plywood, lumber and gypsum wallboard whether they are unfinished or covered with paint, varnish or cellulosic wallpaper as shown previously in Table 2.

There are also special fire-retardant paints and coatings that can substantially reduce the flame-spread rating of an interior surface. These coatings are particularly useful when rehabilitating an older building to reduce the flame-spread rating of finish materials to acceptable levels, especially for those areas requiring a flame-spread rating no greater than 25.

In general, the NBCC sets the maximum flame-spread rating for interior wall and ceiling finishes at 150, which can be met by most wood products.

For example, 6mm Douglas Fir plywood may be unfinished, painted, varnished or covered with conventional cellulosic wallpaper. This has been found to be acceptable on the basis of actual fire experience.

This means that in all areas where a flame-spread rating of 150 is permitted, the majority of wood products may be used as interior finishes without special requirements for fire-retardant treatments or coatings.

Flooring

In a room fire, the flooring is usually the last item to be ignited, since the coolest layer of air is near the floor.

For this reason, the NBCC, like most other codes, does not regulate the flame-spread rating of flooring, with the exception of certain essential areas in high buildings:

• exits
• corridors not within suites
• elevator cars
• service spaces

Traditional flooring materials such as hardwood flooring and carpets can be used almost everywhere in buildings of any type of construction.