The Waterproofing Capabilities of Moisture Resistant Plasterboard

10th May 2024 -

Moisture damage is a common issue that impacts the integrity and longevity of buildings. Traditional drywall and other types are susceptible to water penetration, leading to swelling, mould growth and eventual deterioration. 

To address this, moisture resistant plasterboard is used to withstand exposure to moisture and humidity. Here, we delve into the waterproofing plasterboard capabilities, exploring their composition, characteristics and applications.

Is moisture resistant plasterboard fully waterproof?

Also commonly referred to as green plasterboard, it has several limitations that prevent them from being considered water resistant plasterboard. Below, we detail the reasons why moisture resistant plasterboard is not fully waterproof. 

Porous nature: Despite the specialised core and facing materials, moisture resistant boards still have a porous structure. Eventually, they allow water to penetrate if exposed for an extended period. The gypsum core, while treated to resist moisture, still absorbs water over time.

Seams and joints: The seams and joints between boards, as well as areas around fixtures, fittings and penetrations, act as potential entry points for water if not properly sealed and treated.

Susceptibility to impact damage: Moisture resistant boards become compromised if subjected to physical impact or damage. This creates cracks or openings that allow water to seep through.

Resistance to hydrostatic pressure: While these boards can handle moderate moisture and vapour levels, they are not designed to withstand significant water pressure. 

Limitations in extreme conditions: Moisture resistant plasterboard is not suitable for areas with constant water contact, standing water or high-moisture environments. For example, environments such as steam rooms or saunas, where the boards become saturated and lose their structural integrity.

Potential for mould growth: Even though moisture resistant boards are designed to resist moisture, prolonged exposure to dampness can lead to mould growth. 

How long do moisture resistant boards last?

The lifespan varies significantly depending on several factors. Their long-term performance is influenced by the degree of water exposure, installation quality and environmental conditions.

Exposure level

• Light moisture exposure (high humidity; occasional splashing): Under these conditions, moisture resistant plasterboards maintain their water-resistant properties for several years. This typically ranges from 5-10 years before showing signs of degradation or water penetration.
• Moderate moisture exposure (frequent splashing; condensation): In areas with more consistent moisture exposure, the boards may start to allow water penetration after 3-5 years. 
• Direct water exposure (standing water; flooding): Moisture resistant plasterboards are not designed to withstand direct and prolonged water exposure. In such cases, water penetration occurs within a matter of weeks or months. It can lead to significant damage and potential structural issues.

Installation quality

• Proper installation techniques, including sealing of joints, edges and penetrations, are crucial in extending the longevity of moisture resistant plasterboards against water penetration.
• Poorly installed boards with gaps, unsealed joints or improper fastening allow water to penetrate much sooner.

Environmental conditions

• Temperature and humidity levels impact the performance of moisture resistant plasterboards over time.
• High temperatures and humidity accelerate the degradation of the boards. This potentially allows water penetration at a faster rate.
• Adequate ventilation and climate control in the affected areas help maintain water-resistant properties for longer.

Does plasterboard thickness affect waterproofing?

Yes, the thickness of the moisture plasterboard does affect its waterproofing capabilities. Thicker boards generally provide better resistance to water penetration and absorption compared to thinner ones. 

• The thicker core acts as a more substantial barrier against moisture penetration.
• Thick boards tend to be denser, enhancing resistance to water absorption and swelling.
• Increased thickness provides more material for the water to travel through before reaching the other side.

Thicker moisture resistant plasterboard is recommended in areas with higher moisture exposure or direct water contact. For example, plasterboard for bathrooms, kitchens and utility rooms will require 12.7mm (½ inch) boards for moderate humidity. Also, 15.9mm (⅝ inch) or 19mm (¾ inch) boards are better for prolonged high humidity or direct water exposure.

How to boost moisture board performance

Green plasterboards offer improved water resistance compared to standard boards. However, there are additional measures that can be taken to further maximise their waterproofing capabilities. Protect your wall areas, tiles and structures from potential water damage with the right techniques, tools and materials outlined below.

1. Waterproof membranes or coatings

• The application of a waterproof membrane or coating over a moisture resistant plasterboard sheet adds an extra layer of protection. 
• Membranes or coatings are typically made of materials like liquid-applied membranes, adhesive sheets or specialised paints and sealants.
• They create a seamless barrier. This prevents water from penetrating the board's surface and seals potential entry points.

2. Proper sealing of joints and seams

• Joint and seam areas between boards are potential areas where water can penetrate. 
• Applying a high-quality sealant or waterproof tape over these joints is key to creating a continuous, seamless surface.
• Specialised sealants or tapes designed for moisture resistant boards ensure proper adhesion and long-lasting protection.

3. Reinforced corner beads and trims

• Corners and edge areas are particularly vulnerable to water damage and impact.
• Install reinforced corner beads and trims, specifically designed for moisture resistant applications. This provides additional strength and protection.
• These accessories are typically made of galvanised steel or plastic, offering durability and resistance to moisture and impact.

4. Proper installation techniques

• Following the manufacturer's guidelines for installing moisture resistant boards is essential for waterproofing performance.
• This includes using the correct fasteners (such as corrosion-resistant screws or nails). Also, maintain proper spacing and ensure a snug fit between boards.
• Proper installation minimises gaps and potential entry points for water. 

Can you fix moisture resistant boards after water damage?

In some cases, it may be possible to repair the affected areas. However, the extent of repairs required depends on the level of water damage and the duration of exposure.

Minor water damage

• Minor water damage, such as a small leak or spill that was promptly addressed, may be possible to repair. 
• The repair process typically involves removing the damaged sections of the board, allowing the remaining area to dry completely. 
• Plus, patching or replacing the removed sections with new moisture resistant plasterboard.
• Proper sealing of the joints and seams with waterproof sealants or tapes is important to prevent future water penetration.

Moderate water damage

• In cases such as prolonged humidity or consistent moisture exposure, assess the extent of the damage. Determine if the boards have lost their structural integrity or if mould growth has occurred.
• Depending on the severity, sections of the affected boards may need to be replaced. This ensures that any moisture sources are addressed and the area is properly dried.
• Additional waterproofing measures, such as the application of waterproof membranes or coatings, may be necessary. 

Severe water damage

• With severe water damage, such as flooding or prolonged exposure to standing water, it is generally recommended to replace the entire affected section. 
• Attempting to repair a panel that has been saturated or exposed to significant water intrusion compromises its structural integrity. It also increases the risk of mould growth or further water damage.
• Complete removal and replacement of damaged boards, addressing the underlying issues and introducing waterproofing measures are crucial. 

What is the future of moisture resistant plasterboard?

There is a demand for more advanced solutions to enhance the waterproofing benefits of moisture resistant insulated plasterboard. Manufacturers are exploring new materials and technologies to improve water resistance and address the limitations. 

1. Innovative core compositions

Alternative core materials that exhibit superior water-resistant properties are being considered compared to traditional gypsum cores. Some potential candidates include cement-based cores, fibre-reinforced composites or even synthetic materials designed to prevent water absorption.

2. Advanced facing materials

As outlined above, the facing materials play a key role in preventing water penetration. Future developments may involve the use of highly water-repellent coatings, hydrophobic materials and nanomaterials to create a strong barrier against moisture.

3. Integrated waterproofing systems

Rather than relying solely on the plasterboard sheets, future products may incorporate integrated waterproofing systems within the board's structure. This includes built-in membranes, self-sealing joints or pre-applied coatings that provide a comprehensive waterproofing solution.

4. Smart moisture monitoring

Advancements in smart technology may lead to the development of smart moisture resistant plasterboard systems. These systems could potentially monitor moisture levels in real-time, alerting users to potential water intrusions or leaks.

5. Enhanced impact resistance

In addition to waterproofing capabilities, future boards may also incorporate features that improve overall durability. This could include reinforced cores, specialised facings or even self-healing properties to minimise the risk of cracks or damage.