How Moisture Resistant Plasterboard Prevents Mould Growth

Mould growth is a serious issue that causes structural damage and health problems in all buildings. An effective way to prevent mould is by installing moisture resistant plasterboard. The specialised material is designed to withstand high humidity levels and resist the growth of mould and mildew.

This feature explores how moisture resistant plasterboard contributes to the prevention of mould growth. We also outline how it can improve indoor air quality by reducing the risks associated with mould infestations. 

What is moisture resistant plasterboard?

Also known as green plasterboard, it is a specialised panel type made from gypsum that is designed to resist moisture absorption. It has a dense gypsum core that is less porous than regular drywall. As a result, it makes it more difficult for water to penetrate.

The face and back of moisture resistant plasterboard are covered with moisture and mould-resistant green coating. This special facing acts as an additional barrier against moisture from high humidity levels or water exposure.

The green board covering contains special compounds that hinder the growth of mould and mildew. Learn more about the properties of moisture resistant plasterboard with our comprehensive guide. 

4 benefits of moisture resistant plasterboard

Its unique features offer several key benefits, particularly in preventing mould growth. In this section, we discover the 4 pros of moisture plasterboard. 

1. Mould and moisture resistance

The mould resistance is achieved through the addition of specialised chemicals and materials during the manufacturing process. These include fungicides, which are substances that prevent the growth of mould and mildew.

Also, the core of the plasterboard is often made from moisture-resistant materials like fibreglass or treated cellulose. Both materials do not provide a suitable environment for mould spores to germinate.

2. Durability and longevity

Moisture resistant plasterboard is engineered to maintain its structural integrity even when exposed to high humidity. The core materials are less prone to swelling, warping or disintegrating when wet. Plus, the facing materials provide an added layer of protection against moisture penetration, further boosting the board's durability.

3. Indoor air quality

Mould growth releases spores and other harmful substances into the air. This triggers allergic reactions, respiratory issues and other health problems. By preventing mould growth, moisture resistant plasterboard helps maintain a healthier indoor environment by reducing the presence of these airborne contaminants.

4. Versatility

Moisture resistance and durability make it suitable for a wide range of applications beyond plasterboard for bathrooms and utility rooms. For example, it is used in basements to protect against moisture seepage.

Also, it is used for outdoor structures like covered patios or pool houses to withstand exposure to the elements. In addition, moisture-resistant plasterboard is installed in commercial settings like restaurants where moisture control is crucial.

How to prevent mould with moisture resistant plasterboards

The effectiveness of the moisture board can be compromised by improper installation. To ensure optimal performance and maintain a healthy indoor environment, it is important to understand the common pitfalls and take appropriate measures.

Inadequate sealing and gaps

If there are gaps or openings left around the edges, corners or cutouts for fixtures, moisture seeps through and accumulates behind the boards. This creates a warm, damp environment where mould spores germinate and spread.
Solution: To prevent this, all joint, edge and opening areas must be properly sealed using moisture-resistant joint compound, tape or caulking. Any gaps around pipes, electrical boxes, or other penetrations should be meticulously sealed. This ensures a continuous, airtight barrier.

Improper vapour barrier installation

A vapour barrier is a key component when installing moisture resistant plasterboard. It prevents warm, moist air from penetrating the wall cavity and condensing inside. Without a proper vapour barrier, moisture migrates through the wall cavity and becomes trapped. This leads to condensation.
Solution: It is essential to install a suitable vapour barrier, such as polyethylene sheeting or specialised vapour retardant membranes, behind the moisture resistant plasterboard This ensures it is properly sealed and continuous throughout the installation.

Lack of ventilation

Areas prone to high moisture levels like a bathroom or kitchen require adequate ventilation to prevent excessive humidity and condensation. If these spaces are not properly ventilated, the moisture levels become too high. Condensation will form on surfaces, including the moisture resistant plasterboard. This creates the perfect environment for mould spores to thrive.
Solution: To combat this issue, installing exhaust fans or operable windows effectively removes moist air and promotes air circulation. Also, proper insulation helps prevent condensation by minimising temperature differences between surfaces.

Improper board handling

Moisture resistant plasterboard can become compromised if it is exposed to water or excessive moisture during handling, storage or installation. If a sheet becomes saturated before installation, it creates an environment for mould growth once fitted.
Solution: It is essential to store the boards in a dry, protected area and handle them carefully to prevent water exposure. Any boards that have become saturated or damaged should be discarded and replaced. This is because they no longer provide the intended moisture resistance.

Failure to address underlying moisture

Installing moisture resistant plasterboard alone is not a solution if there are underlying moisture problems in the structure. This includes leaks, rising dampness or condensation issues. If these root causes of moisture are not addressed, the plasterboard becomes compromised and mould growth occurs.
Solution: Identify and resolve any sources of moisture or water intrusion before installing the moisture resistant plasterboard. You may need to fix leaks, improve insulation, implement waterproofing measures or address any other moisture-related issues in the building.

Is moisture resistant plasterboard waterproof?

While moisture resistant plasterboard offers excellent protection against humidity and moisture, it should not be considered as a waterproof plasterboard material. Below, we outline these reasons. 

• Core composition: Although the core of moisture resistant plasterboard is made from dense, water-resistant materials like treated gypsum, they are not entirely resistant to water. If exposed to prolonged or substantial water exposure, the core eventually becomes saturated. This leads to swelling, disintegration and potential structural damage.
• Facing material limitations: While the facing materials provide an additional layer of water resistance, they are not designed to withstand direct, sustained water exposure or immersion.
• Susceptible to leaks: Moisture resistant plasterboard is not suitable for areas prone to flooding or continuous water leaks. Prolonged exposure to standing water or a leak compromises the integrity of a board. 
• Lack of waterproofing properties: Moisture resistant plasterboard is not a substitute for dedicated waterproofing plasterboard materials. It does not have the same level of waterproofing capabilities as specialised waterproofing membranes, tiles or other waterproofing products.
• Humidity and moisture protection: Moisture resistant plasterboard is primarily designed to withstand high humidity levels and occasional moisture exposure. This includes condensation or minor water splashes. It is not intended to be a barrier against direct water contact.
• Use with waterproof materials: It is recommended to use waterproof membranes, tiles or other specialised waterproofing products alongside moisture resistant insulated plasterboard. This creates a water resistant plasterboard effect. 

Does moisture-resistant board thickness affect mould growth?

Thickness does not directly influence the potential for mould growth. It does play a role in the overall structural integrity and durability of the boards. However, the resistance to mould growth is determined by the moisture-resistant properties of the materials including facing materials, treatments and core composition. 

However, thick board options offer some added benefits such as heat, fire and sound resistance. This indirectly impacts their ability to prevent mould growth. A thicker board is less likely to be easily damaged or punctured, reducing the risk of moisture penetration and mould growth.

Can you repair mould growth on plasterboards?

If mould growth has occurred, you should address the issue promptly. The first step is a thorough assessment of the affected area. Identify the extent of the mould growth and determine the underlying moisture sources.

Containment is critical to prevent the spread of mould spores to other areas. Establish negative air pressure containment by sealing off the affected area. You can use plastic sheeting and HEPA-filtered air scrubbers. This stops mould spores from dispersing during the removal process.

Mould removal techniques

Depending on the extent of the mould growth and the condition of the plasterboard, you may consider using the various removal techniques below.

• Surface cleaning: For minor, surface-level mould growth, use specialised cleaning solutions and techniques. This includes HEPA vacuuming or damp wiping to remove the mould from the surface of the plasterboard.
• Encapsulation: If the mould growth is not extensive, you can opt to enclose the affected area with a specialised sealant or adhesive. The technique helps to contain any remaining mould spores and prevent future growth.
• Removal and replacement: For more severe cases of mould growth or significant damage, removal and replacement is the best option.