Fire Door Size Guide: Standard UK Sizes & Dimensions

Choosing the correct fire door size is important for safety, performance, and a successful installation. Fire doors are designed to slow the spread of fire and smoke, giving occupants valuable time to evacuate safely. However, selecting the right size is just as important as choosing the correct fire rating.

In this fire door size guide, we explain standard UK fire door dimensions, common sizes, thickness requirements, and how to measure your existing door opening before purchasing a replacement.

What Is the Standard Fire Door Size in the UK?

The most common standard fire door size in the UK is 1981mm x 762mm x 44mm. This size is widely used for FD30 fire doors, which provide up to 30 minutes of fire resistance when correctly installed.

However, fire doors are available in a range of sizes to suit different properties, door frames, and building requirements. The correct size will depend on your existing opening, the required fire rating, and the manufacturer's specifications.

Standard Fire Door Sizes Chart

The 762mm width is one of the most commonly selected fire door sizes in UK homes. Larger sizes are often used in commercial buildings or areas where wider access is required.

Fire door sizes can vary depending on the manufacturer and certification requirements, so always check the product specifications before ordering.

How Thick Is a Fire Door?

Fire door thickness depends on the level of fire protection required.

• FD30 fire doors: Usually 44mm thick
• FD60 fire doors: Usually 54mm thick

The thickness of a fire door helps determine its ability to resist fire and heat for a specific period. A thicker fire door is generally required for higher fire resistance ratings.

How to Measure a Fire Door Correctly

Before replacing a fire door, accurate measurements are essential. Incorrect measurements can result in poor fitting, installation problems, or the need for additional adjustments.

Follow these steps when measuring:

Measure the Door Height

Measure from the top edge of the door to the bottom edge. Take measurements at both sides to ensure the door is not uneven.

Measure the Door Width

Measure across the door from one side to the other. For accuracy, check the width at the top, middle, and bottom.

Measure the Door Thickness

Measure the thickness of the door slab from the edge. This helps identify whether the replacement door matches the required fire rating.

Check the Frame Size

The existing door frame should also be measured to ensure the new fire door fits correctly. Consider the frame width, height, and available clearance.

Choosing the Right Fire Door Size for Your Property

When selecting a fire door, consider the following factors:

• Required fire rating, such as FD30 or FD60
• Existing door frame dimensions
• Door opening size
• Building requirements
• Manufacturer installation guidelines

For most residential properties, FD30 fire doors are a common choice. Commercial properties and buildings with higher safety requirements may require doors with increased fire resistance.