No Products in the Cart
Plasterboard thickness plays a much bigger role in building performance than most people realise. While 12.5mm plasterboard is the standard, most commonly used option in UK construction, there are many situations where upgrading to 15mm plasterboard provides clearer benefits in terms of strength, acoustic performance, fire protection and durability. Understanding these differences helps builders, renovators and self-builders choose the right specification for each area of a property.
This guide explains exactly when to use 15mm plasterboard instead of 12.5mm, why the difference matters, and how to ensure you’re choosing the correct material for your project. For a full range of boards, check out our extensive plasterboard collection.
The thickness of plasterboard affects several key performance factors, including:
Although 12.5mm is ideal for most general internal walls and ceilings, 15mm boards offer significant advantages in more demanding settings.
Fire protection is one of the most common reasons to use 15mm plasterboard. In areas where Building Regulations demand improved fire resistance — such as internal escape routes, garages, or separating walls between dwellings — 15mm boards are often specified because they help achieve the required protection levels without needing complicated multi-layer systems. For fire rated boards, you can view our fire rated plasterboards.
For example, a single layer of 15mm fire-rated plasterboard can provide similar protection to two layers of standard 12.5mm, depending on the product class and system design. This can save installation time, reduce screw count, and simplify finishing.
Sound insulation relies heavily on mass. The heavier the board, the better its ability to block airborne noise. This makes 15mm plasterboard a strong choice for:
When combined with acoustic mineral wool and resilient bars, 15mm boards significantly outperform 12.5mm equivalents.
15mm plasterboard is less prone to dents, deformation and cracking because of its increased rigidity. This makes it ideal for areas that are regularly exposed to physical impact, including:
Where durability is key, 15mm boards provide a more robust wall surface capable of withstanding everyday knocks and wear.
Ceilings can sag over time if the plasterboard isn’t rigid enough or if joists are spaced wider than usual. Because 15mm plasterboard is heavier and more resistant to deflection, it is often the preferred choice for:
It helps maintain a flat, stable finish over many years.
In some energy-efficient builds — particularly those using passive or low-energy principles — greater wall mass helps stabilise indoor temperatures. While plasterboard alone cannot insulate a room effectively, the additional thickness of 15mm contributes to improved thermal stability when combined with insulation such as PIR, mineral wool, wood fibre or systems like dot-and-dab.
Although 15mm has clear advantages, 12.5mm plasterboard remains appropriate for many standard applications. It is usually the best option when:
12.5mm boards are more versatile, easier to cut, and usually cheaper — making them the standard plasterboard thickness for most domestic jobs.
| Feature | 12.5mm Plasterboard | 15mm Plasterboard |
|---|---|---|
| Fire resistance | Suitable for standard partitions | Better — often required in fire-rated systems |
| Acoustic performance | Good for general internal walls | Superior mass & sound blocking |
| Impact resistance | Moderate | High — ideal for high-traffic areas |
| Ease of installation | Lightweight and easy to handle | Heavier and more labour-intensive |
In most homes, 12.5mm plasterboard is perfectly adequate for day-to-day rooms and ceilings. However, whenever you need enhanced performance — whether acoustic, fire-rated, or simply greater durability — upgrading to 15mm plasterboard is a smart and forward-thinking choice.
Think of 15mm plasterboard as a premium version built for demanding environments. If the space needs to be quieter, stronger, safer or more resistant to wear, stepping up to 15mm ensures the wall or ceiling will stand the test of time.
Note: Always consult manufacturer datasheets and local Building Regulations to confirm the correct plasterboard specification for fire, sound or structural performance requirements.
