Plasterboard Thickness: What you Need to Know

Plasterboard comes in a selection of thicknesses to accommodate different building needs. Commonly, you’ll find:

• 1/4 inch (6.35 mm): This slim profile is ideal for creating smooth curves in design features.
• 3/8 inch (9.52 mm): A slightly thicker board, perfect for refinishing surfaces or mending areas.
• 1/2 inch (12.7 mm): This is the go-to thickness for most home walls and ceiling installations.
• 5/8 inch (15.88 mm): Chosen for its superior abilities in noise reduction and fire retardation, this thickness is a staple in commercial settings.

Regarding width, plasterboard is typically available in two standard widths: 48 inches (1220 mm) to suit the common spacing of wall studs and 54 inches (1370 mm) for broader surfaces. The lengths of these boards can extend from the standard 8 feet (2440 mm) up to 12 feet (3660 mm) or more, facilitating smoother finishes with minimal joints on expansive wall areas. For unique construction projects, manufacturers can also produce bespoke dimensions to fulfil specific installation requirements.

These specific sizes ensure that drywall can meet diverse construction standards and performance requirements.

Factors influencing plasterboard thickness

Various factors influence the thickness of the plasterboard. Below are some of the main ones:

Acoustic resistance

Acoustic resistance in plasterboard refers to its ability to reduce the transmission of sound between spaces, a critical feature in building design for privacy and noise control. To achieve this, plasterboard thickness is a crucial factor. 

Standard plasterboards offer some sound insulation at 1/2 inch (12.7 mm) thick, but for enhanced acoustic performance, thicker boards are preferred. These can range from 5/8 inch (15.9 mm) to specialised acoustic boards that may be even thicker, incorporating multiple layers or denser core materials to obstruct sound waves further, providing a much quieter environment. The specific choice depends on the desired level of soundproofing required for a particular space.

Type of Plasterboard	Length	Width	Thickness
Knauf Soundshield Plus	2400mm	1200mm	12.5mm
Knauf Soundshield Plus	2400mm	1200mm	15mm
British Gypsum Gyproc SoundBloc	3000mm	1200mm	15mm
British Gypsum Gyproc SoundBloc	2400mm	1200mm	12.5mm
GTEC Acoustic Homespan	2400mm	900mm	15mm

Fire resistant

Fire resistance in plasterboard is its capacity to withstand fire and prevent its spread, an essential consideration for ensuring the safety of buildings and their occupants. The thickness of the plasterboard is a determinant of its ability to act as a barrier against flames and heat. Regular plasterboard offers a basic level of protection, but for enhanced fire resistance, thicker boards are necessary. 

Fire-resistant plasterboards typically start at 5/8 inch (15.9 mm) and can be thicker, sometimes coupled with special fire-retardant additives or fibreglass fibres to enhance their performance. Such boards are crucial in areas where enhanced fire codes are in place and are selected based on the fire-rating requirements specified for a building project.

Type of Plasterboard	Length	Width	Thickness
Fireproof Plasterboard	3000mm	1200mm	12.5mm
Fireproof Plasterboard	3000mm	1200mm	15mm
British Gypsum Gyproc Fireline	3000mm	1200mm	12.5mm
British Gypsum Gyproc Fireline	3000mm	1200mm	15mm
GTEC Fire Board	3000mm	1200mm	12.5mm

Thermal insulation

Thermal insulation in plasterboard refers to its ability to retain heat within a space, contributing to energy efficiency and comfort. The thickness of the plasterboard contributes to its thermal performance—thicker boards generally offer better insulation because they have more material to slow down the transfer of heat. 

While standard plasterboard provides some level of insulation with thicknesses like 1/2 inch (12.7 mm), boards designed specifically for thermal insulation are often thicker, ranging up to 40 mm or more. Some are integrated with insulating materials or have a higher density core to enhance this property, making them ideal for exterior walls or places with high thermal requirements.

Type of Plasterboard	Length	Width	Thickness
Warmline PIR Insulated	2400mm	1200mm	102mm
Warmline PIR Insulated	2400mm	1200mm	32.5mm
British Gypsum Gyproc ThermaLine Basic	2400mm	1200mm	40mm
British Gypsum Gyproc ThermaLine PLUS	2400mm	1200mm	48mm
British Gypsum Gyproc ThermaLine SUPER	2400mm	1200mm	90mm

Water-resistant

Water resistance in plasterboard is its ability to withstand moisture and humidity without deteriorating, which is crucial for areas prone to wet conditions, like bathrooms and kitchens. To address this, plasterboards are often treated with water-repellent coatings or manufactured with water-resistant cores. The thickness of these boards can influence their moisture-handling capabilities.

While the standard thickness of 1/2 inch (12.7 mm) provides some moisture resistance, thicker boards, such as those at 5/8 inch (15.9 mm), can offer enhanced durability and a better barrier against water vapour. These water-resistant plasterboards ensure longevity and protection in environments with high exposure to moisture.

Type of Plasterboard	Length	Width	Thickness
Standard	2400mm	1200mm	9.5mm
Standard	2700mm	1200mm	12mm
Standard	2400mm	1200mm	15mm
Gypsum Gyproc Wallboard	1800mm	900mm	9.5mm
GTEC Standard Board	1800mm	900mm	15mm

FAQs about plasterboard thickness

What’s the reason for the various plasterboard thicknesses on the market?

Plasterboard thickness is tailored to its application – thinner boards bend for intricate designs, while thicker ones are for areas needing sound or fire protection. This range serves different structural and building environment requirements.

Is it possible to use a plasterboard of any thickness for my project?

The choice of plasterboard thickness should align with the project’s demands. For typical home projects, a 1/2 inch plasterboard is standard, whereas areas necessitating greater sound or fire protection should consider using 5/8 inch.

Does a thicker plasterboard equate to better quality?

Thicker plasterboard does offer enhanced qualities in noise control and fire safety. Yet, quality also depends on the plasterboard’s specific features, like whether it’s moisture-resistant or designed for high fire resistance.

What should I know about the limits on plasterboard thickness?

The practical limit on thickness is often governed by structural concerns and building codes. While 5/8 inch is typically the upper standard for enhanced characteristics, any greater thickness may need additional structural support.

How is the appropriate plasterboard thickness determined?

Selecting the correct thickness involves assessing room use, acoustic requirements, moisture exposure, and structural capacity. Advice from construction professionals or references to building regulations can also be invaluable.