How to Navigate Regulations with Moisture Resistant Plasterboard

Whether you are renovating a bathroom or building a new kitchen, adhering to relevant regulations is essential. These regulations are in place to ensure the safety and longevity of structures, as well as help you maintain compliance.

This article provides a comprehensive guide to navigating the regulations on moisture resistant plasterboard. From sheet installation and maintenance to understanding relevant regulations, we cover all aspects of building code-compliant projects.

How to identify moisture plasterboard regulations

Approved Document B and Approved Document C under the UK Building Regulations 2010 provide specific guidance on moisture resistant drywall (also known as green plasterboard) in different applications. Below are the key regulations to consider for panel installation in common areas.

Bathroom and shower areas (Approved Document C)

• Bathroom and shower wall boards with a minimum thickness of 12.5mm should be used for tiling on moisture resistant plasterboard.
• Boards should extend to a height of at least 2 metres above the shower tray or bathtub’s highest point.

Swimming pool enclosures (Approved Document C)

• Moisture boards should be at least 12.5mm thick for wall and ceiling areas.
• For high humidity levels, boards with improved moisture resistance (glass-reinforced gypsum boards) may be required.

Commercial kitchens (Approved Document B)

• Fire resistant and moisture resistant plasterboards with a minimum thickness of 15mm should be used for walls and ceilings.
• In areas with high heat and humidity, such as near commercial ovens, boards with enhanced moisture and heat resistance may be necessary.

Basements and cellars (Approved Document C)

• A minimum thickness of 12.5mm is recommended for walls and ceilings in areas prone to condensation or water ingress.
• In cases of severe moisture exposure or frequent flooding, more robust solutions like tanking systems may be needed.

Is moisture resistant and vapour plasterboard the same?

They are not the same and have distinct properties and intended applications. Understanding the differences between these 2 types of plasterboard is important for compliance and achieving the best performance. 

Moisture resistant plasterboard

As outlined above, it is designed to withstand direct exposure to moisture and humidity. Although it is not a fully waterproof plasterboard, it features a moisture resistant core and specialised facings that resist water penetration. This type of plasterboard is recommended for use in areas with high moisture levels.

Vapour plasterboard

Also known as foil backed plasterboard or vapour control plasterboard, it is designed to control vapour transmission. It features a metallic foil or reinforced plastic facer on one side. This acts as a vapour barrier to prevent it from penetrating the board and causing condensation within the wall or ceiling cavity.

It is often used in conjunction with moisture resistant boards because it is not considered a fully water resistant plasterboard. Approved Document L recommends the use of vapour control layers to reduce the risk of condensation and improve energy efficiency. 

What is the best installation method for compliance?

Adhering to proper installation is key to ensuring moisture resistant plasterboard meets the requirements outlined in Building Regulations. Here are the installation methods that must be followed for a compliant plasterboard project.

Sealing and taping joints

All joint spaces between boards must be sealed with a moisture resistant sealant or tape. This prevents moisture from penetrating through the joints, which could lead to deterioration of the plasterboard system. Sealing joints is a requirement under Approved Document C to create reliable resistance to moisture ingress.

Staggered board layout

When installing moisture resistant boards on walls or ceilings, the layout should feature staggered joints rather than aligning them in a straight line. This staggered pattern improves the overall strength and stability of the system.

It reduces the risk of cracking or deformation because of moisture exposure. Staggered layouts are recommended in Approved Document C to boost structural integrity. 

Continuous vapour control layer (VCL)

In areas such as commercial kitchens or pool enclosures, a continuous vapour control layer (VCL) should be installed behind the moisture resistant boards. This impermeable membrane acts as a barrier.

It prevents vapour from penetrating wall or ceiling cavities and compromising insulation or structural elements. Fitting a VCL is a requirement under Approved Documents C and L to maintain energy efficiency and prevent condensation issues.

Waterproof membranes and tanking systems

In areas with frequent water exposure or potential flooding, such as basements or wet rooms, waterproof membranes or tanking systems should be used in conjunction with moisture resistant boards.

These systems provide an additional layer of protection against water ingress, preventing moisture from reaching the plasterboard and causing damage. Approved Document C recognises the need for enhanced waterproofing measures in high-risk areas.

Can you face action for poor moisture board installation?

Yes, failure to comply with Building Regulations with the installation of moisture resistant plasterboard will have serious legal implications. Non-compliance may lead to enforcement action from local authorities.

This includes the issuance of notices and fines. Prosecution may also be a possibility in severe cases, leading to potential imprisonment. Below are the key considerations to take into account.

Breach of contract/negligence

You have a duty of care to ensure work is carried out to the required standards and in compliance with regulations. Incorrect installation with substandard materials may constitute a breach of contract between you and the client.

This could lead to legal action for damages equal to the total losses, repair costs to fix the work or compensation.

Health and safety risks

Improper installation creates health hazards, such as mould growth or structural issues which can put individuals at risk. Under the Construction (Design and Management) Regulations 2015, you can be held legally responsible for health and safety breaches. Penalties include individual fines of up to £20,000 and unlimited fines for companies. Also, imprisonment is a possibility for severe breaches. 

Insurance implications

Failure to comply with Building Regulations may invalidate certain insurance policies. This can leave you unprotected in case of claims or disputes. If an issue arises because of improper installation, insurance companies may refuse to cover the costs or damages. As a result, you may face financial implications and potential litigation for the recovery of losses.

Does moisture resistant plasterboard need maintenance?

Yes, it requires maintenance to ensure it continues to meet the performance standards outlined in the Building Regulations. Neglecting maintenance can compromise the board's integrity, leading to potential non-compliance and putting the structure at risk.

The frequency of maintenance depends on the specific application and the level of moisture exposure. Here are some general guidelines.

• Bathrooms and shower areas: These areas should be inspected annually for any signs of moisture damage, mould growth or deterioration. Caulking and sealants around fixtures should be checked and replaced as needed.
• Swimming pool enclosures: Because of the high humidity levels, moisture resistant plasterboard in these areas should be inspected every 6 months for any signs of damage.
• Commercial kitchens: The combination of moisture, heat and grease exposure can be particularly harsh on plasterboard. Quarterly inspections are recommended to check for any issues.
• Basements and cellars: Areas prone to condensation or water ingress may require more frequent maintenance. Conduct inspections every 6 months or after any significant water exposure.