Fire-Rated Plasterboard: What Is It and How Is It Used?

Fire-rated plasterboard is a type of plasterboard specifically designed to prevent the spread of fire. Typically, a fire-rated plasterboard is given a rating that corresponds to the length of time it can offer resistance to fire. A 30 or 60-minute fire-rated board is the most commonly used for internal walls and ceilings. Fire-rated plasterboard also helps to ensure that walls and ceilings are better insulated.

What is Fire-Rated Plasterboard Used For?

Fire protection is the main benefit of fire-rated plasterboard, so it is used for places where a fire is a safety concern. By adding fire protection to structural parts of a building, if a fire does occur then you will reduce the chances of any irreparable damage to the structural elements of the building.

Timber stud partitions in walls are more flammable than metal studs, so fire-rated plasterboard can stop the chances of timber studs causing a fire to spread in partition walls. However, you can use it on masonry walls too.

Fire Rating Chart

The government sets fire ratings for building materials and products. They are as follows: 

• Class 1
• Class 2
• Class 3 
• Class 4

There is also a lesser-used ‘Class 0’ fire rating. Class 1 offers the best fire resistance and the ratings get progressively less effective further down the rankings. The rating is based on the spread of flame and is tested under rigorous conditions before the product or material comes to market. 

The fire resistance of plasterboard is based on how well they project building ‘elements’. These include walls, floors, ceilings and partitions. In this case, the plasterboard only forms part of the overall construction - so other things may affect the fire resistance of a building. Building regulations demand a minimum period of fire resistance provided by these ‘elements’ of 30 minutes or more.

The types of fire-rated plasterboard you are likely to see are coloured either light pink or red - so it is easy to recognise that these products are specific to fire resistance.

Fire-rated plasterboard typically has the following available resistance times:

• 30 minutes
• 60 minutes
• 90 minutes
• 120 minutes

To achieve these ratings manufacturers use different thicknesses, as well as different fire-resistant additives within their gypsum boards. Common thicknesses include the following:

• 12.5 mm
• 15 mm
• 19 mm

As a general rule,  thicker boards tend to have a longer fire resistance time, but it is possible to find specialist products that provide higher fire resistance times within a thinner board. 12.5 mm is the minimum thickness you can get.

The government provides documentation for fire safety in the form of building regulations. There are two main documents to look at: one for dwellings and one for buildings other than dwellings, which can help you to further improve fire safety.

What Brands of Fire-Rated Plasterboard Are Available?

Selecting the best brand of fire-rated plasterboard can be a challenge, which is why we offer our clients personal advice and guidance. We recommend the following brands, which are known for their high performance and fire resistance:

• British Gypsum: A historical and high-quality brand that is now part of the Gobain Construction Product UK subsidiary. Their main series of fire-rated plasterboard products is called Gyproc Fireline.
• Knauf: This originally American producer now produces quality fire-rated plasterboard all over the world. The Knauf range of Fire Panel products is the main series of their fire-rated plasterboard range.
• Siniat: Siniat is another global brand known for a wide variety of quality plasterboards. When it comes to fire-rated plasterboard they offer a product called  GTEC Fire Board - which is both fire and moisture-resistant. 

The fire resistance performance of British Gypsum’s Gyproc FireLine products is relatively high as it offers a 1-hour fire rating and is designed for high-risk areas. This makes it an excellent choice if you are unsure what board to choose. 

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What Sizes of Fire-Rated Plasterboard Are Available?

While it is possible to cut fire-rated plasterboard to any size, the following board sizes are the most common:

• 600mm x 3000mm
• 1800mm x 900mm
• 2400mm x 1200mm
• 2700mm x 1200mm
• 3000mm x 1200mm

Any of these sizes will offer the same level of fire resistance, but a thicker 15mm board will provide more robust fire resistance for partitions and walls alike.

One consideration is the type of edge you opt for, you have two main choices - a tapered edge or a square edge. Tapered edges can be easier to fit together, so they are the best option for installing fire-rated plasterboards across a large area.

How Do You Fit Fire-Rated Plasterboard?

To install a fire-rated plasterboard ceiling or floor you need to take much the same approach as you would when fitting standard plasterboard. If you are installing on a wall, you can use the tried and tested dot and dab method that uses adhesives and bonding compounds to fix the boards securely in place.

For ceilings, the only real option is mechanical fixings because of the effects of gravity. You can use drywall screws and nails or a combination of different types of fixings. When using fixings, make sure you skim over all fixings with plaster after they are in place - to lower the chances of any air being able to get through.

You can finish and paint, tile or plaster the fire-rated boards once they are in situ - the same way as you would with any other type of plasterboard.

*Please remember to always check the manufacturer guidelines before installing any products, whether it be plasterboard, adhesive or framing systems. If in doubt, always consult a specialist for advice.

FAQs and Useful Information

The following are some commonly asked questions, which provide useful information about fire-rated plasterboard:

Do I Need to Use a Fire-Rated Plasterboard?

Yes. For all ‘elements’ in a building, you are required to have a fire resistance of 30 minutes or more. You can normally achieve this with a fire-rated plasterboard that is 12.5mm or thicker. However, you could theoretically also achieve this with two layers of plasterboard that are at least 9.5mm thick.

What Fire Rating Do I Need?

For internal walls and ceilings, you need a class 1-rated product. If you have any areas of a wall or ceiling, such as exposed timber beams, that are not covered by the plasterboard you can use class 1-rated paints and other coatings to make sure you achieve the appropriate fire resistance time.