CEMBLOC Newsroom

Why Pre-Primed Fibre Cement Boards Still Require Finishing Coats

Wed, 11 Mar 2026 15:41:12 GMT

A guide to pre-primed fibre cement boards, why finishing coats are required, and how to handle minor primer marks.

Why Pre-Primed Fibre Cement Boards Still Require Finishing Coats

Pre-primed fibre cement boards are designed to make installation faster and finishing easier. The factory-applied primer provides a consistent base coat that improves paint adhesion and reduces preparation time on site.

However, it’s important to understand that **a pre-primed board is not a finished surface**. A full paint or coating system is still required once the boards are installed.

In this guide, we explain why finishing coats are necessary and address a common question about minor primer marks that can occasionally appear when boards are separated from a pallet.

What Does “Pre-Primed” Actually Mean?

A pre-primed fibre cement board has a **factory-applied primer layer** designed to prepare the surface for decoration. This primer improves the bonding of paints and coatings while reducing the amount of preparation required on site.

The primer acts as a **base layer only**. It is not intended to be the final exposed finish of the board.

Once installed, the boards should be completed with the appropriate **external or internal paint system**, depending on the application.

Why Finishing Coats Are Still Required

Even when a board is supplied pre-primed, finishing coats are essential for several reasons:

Weather protection – Exterior paint systems protect the board from long-term exposure to moisture and UV.

Uniform appearance – Final coatings ensure a consistent colour and finish across the installation.

Surface durability – Paint systems provide an additional protective layer against general wear and environmental exposure.

For these reasons, pre-primed boards should always be finished in accordance with the chosen paint manufacturer’s recommendations.

Occasional Primer Marks Between Boards

Because pre-primed boards are stacked and transported in pallets, **minor primer transfer or marks can occasionally occur where boards have been in contact during storage or transit**.

In some cases, when separating boards, small areas of primer may appear lighter or darker where the boards have touched. This is simply a result of surface contact between primed faces while stacked.

These marks are **purely cosmetic and do not affect the structural performance or durability of the fibre cement board**.

How to Address Minor Primer Marks

If small primer marks are visible after separating boards from a pallet, they can easily be addressed during normal finishing preparation.

Typical site practice includes:

* Lightly sanding the affected area if required

* Applying a suitable primer or undercoat if needed

* Completing the system with the specified finishing coats

In most cases, the final paint system will **fully cover and blend any minor variations in the primer layer**.

The Purpose of Pre-Primed Boards

Pre-primed fibre cement boards are designed to make projects more efficient by reducing preparation time and providing a reliable base for finishing systems.

As with most primed building materials, the primer is **part of the finishing system rather than the finished surface itself**.

Once the appropriate paint or coating system is applied, the boards deliver the durable, consistent finish expected from fibre cement cladding and lining systems.

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For more information about CEMBLOC® fibre cement boards or finishing recommendations, contact our technical team or explore the product guides available on our website.

Introducing CemBacker® PrePrimed: The Ultimate Ready-to-Use Tile Backer Board

alex@lumifymedia.co.uk (Alex Twigg) — Tue, 03 Jun 2025 12:44:34 GMT

Now Pre-Primed for Faster Installs, Cleaner Worksites, and Superior Tile Adhesion

CEMBLOC® is proud to unveil the latest innovation in tile backing solutions: CemBacker® PrePrimed . Building upon the trusted performance of our original CemBacker® boards, the PrePrimed variant offers enhanced convenience and efficiency for both professionals and DIY enthusiasts.

Why Choose CemBacker® PrePrimed?

1. Ready-to-Use Convenience
CemBacker® PrePrimed comes factory-primed, eliminating the need for on-site priming. This not only saves time but also ensures a consistent, high-quality surface ready for tile adhesive application.

2. Cleaner and Safer Installation
The pre-primed surface significantly reduces dust during cutting and handling, creating a cleaner and safer working environment. This is particularly beneficial in indoor settings where dust control is essential.

3. Enhanced Adhesion
The consistent primer application provides an optimal surface for tile adhesives, promoting stronger bonds and reducing the risk of tile detachment over time.

Retaining Core CemBacker® Benefits

While offering these new advantages, CemBacker® PrePrimed maintains the core features that have made CemBacker® a preferred choice:

Fire Resistance : Still utilising the same A1 fire-rated CemBacker® board but with the addition of a primer, ensuring maximum safety in various applications.
Water Resistant : Highly water-resistant, making it ideal for wet rooms and other moisture-prone areas.
Durability : Supports heavy tiles up to 105kg/m², suitable for both wall and floor installations.
Dimensional Stability : Resistant to warping and deterioration, outperforming traditional materials like plasterboard and plywood.

Available Sizes

CemBacker® PrePrimed is available in two standard sizes to cater to different project needs:

6mm (1200mm x 600mm) : Ideal for floor applications.
12mm (1200mm x 600mm) : Designed for wall installations requiring additional pull strength.

Ideal Applications

CemBacker® PrePrimed is perfect for:

Wet Rooms : Providing a reliable backing in high-moisture environments.
Bathrooms and Kitchens : Ensuring long-lasting tile installations in areas prone to water exposure.
Commercial Spaces : Offering durability and safety in high-traffic areas.
DIY Projects : Simplifying the tiling process for home improvement enthusiasts.

Experience the enhanced efficiency and reliability of CemBacker® PrePrimed.

Whether you're a professional contractor or a DIYer, this ready-to-use tile backer board is designed to streamline your projects and deliver lasting results.

For more information, visit our website or contact our professional team today.

The Power of Modular Construction: Advantages and Applications of Cembloc Systems

alex@lumifymedia.co.uk (Alex Twigg) — Mon, 03 Jul 2023 21:20:00 GMT

Efficiency Unleashed: Accelerating Project Timelines with Cembloc

Introduction:

In today's fast-paced construction industry, time is of the essence. Developers and contractors are constantly seeking ways to accelerate project timelines without compromising on quality. One solution that has revolutionised construction efficiency is the use of Cembloc product range such as the Cemplate , CemBacker and Cembloc Tex , a leading provider of modular building solutions. In this blog, we will explore how Cembloc unleash efficiency, enabling the acceleration of project timelines and ensuring timely delivery of construction projects.

Streamlined Manufacturing Process:

Modular construction with Cembloc begins with a highly efficient manufacturing process. The controlled factory environment allows for precision and speed in producing building components. With standardised production methods, each module is manufactured to exact specifications, eliminating errors and minimising rework. This streamlined manufacturing process significantly reduces construction time by overlapping activities and maximising productivity.

Simultaneous On-Site and Off-Site Work:

One of the key advantages of modular construction is the ability to perform on-site and off-site work simultaneously. While modules are being manufactured in the factory, site preparation, foundation construction, and utility connections can progress at the project site. This parallel workflow eliminates the traditional sequential approach, where each construction phase must be completed before the next one can begin. The result is a dramatic reduction in project timelines, enabling earlier occupancy or utilisation of the building.

Weather-Independent Construction :

Weather delays can be a major setback in traditional construction methods. However, with modular construction using Cembloc, adverse weather conditions have a minimal impact on project timelines. Since a significant portion of the construction work is carried out in a factory-controlled environment, modules are protected from inclement weather during fabrication. This ensures that construction progresses smoothly regardless of external conditions, further reducing delays and ensuring predictable project timelines.

Efficient Project Coordination:

Modular construction with Cembloc requires meticulous project coordination and planning. Each module is manufactured according to a well-defined schedule, ensuring that it arrives at the project site precisely when needed. This eliminates the need for on-site material storage and minimizes the risk of theft or damage. With efficient project coordination, construction activities can be seamlessly synchronized, maximizing efficiency and minimizing downtime.

Enhanced Construction Productivity :

The efficiency of modular construction with Cembloc translates into enhanced construction productivity. The reduction in on-site work, along with the optimised workflow, allows construction teams to focus on critical tasks, such as module assembly, utility connections, and interior finishing. The controlled factory environment also enables better supervision and quality control, ensuring that each module meets the highest standards. The result is an overall increase in construction productivity and a significant reduction in project timelines.

Conclusion:

Cembloc have revolutionised construction efficiency by unleashing the power of modular construction. Through streamlined manufacturing processes, simultaneous on-site and off-site work, weather independence, efficient project coordination, and enhanced construction productivity, Cembloc accelerate project timelines and enable timely delivery of construction projects. By embracing the efficiency unleashed by Cembloc , developers and contractors can achieve faster project completion, reduce costs, and gain a competitive edge in the ever-evolving construction industry.

Risks of MG0 Board In Construction

alex@lumifymedia.co.uk (Alex Twigg) — Mon, 30 Jan 2023 16:30:30 GMT

The purpose of this article is to educate and provide evidence-based resources to the UK market on the comparison of MgO and Fibre Cement. We will compare key factors such as price, fire safety, water resistance, and focus on durability, a crucial factor often overlooked. We will examine construction industry practices to highlight potential issues with MgO, enabling you to make an informed decision.

Risks of MG0 Boards?

To start this article is best to dive into the deep end. As of April 2020, NHBC (National House-Building Council) announced "NHBC will not accept MgO building boards on buildings where the foundations are begun on or after 30 April 2020 under its insurance warranty" and "Where MgO building boards have already been, and are currently being, installed on buildings, you should use an alternative product if it is practical to do so."

- Reference: https://www.nhbc.co.uk/builders/products-and-services/techzone/technical-updates

Alongside NHBC, the LABC announced "LABC Warranty no longer accept the use of all types of Magnesium Oxide board (MgO) on any of our structural warranty schemes." 15 days earlier.

- Reference: https://www.labcwarranty.co.uk/technical-blog/updated-guidance-for-magnesium-oxide-boards-mgo

Leading render manufacturers have prohibited the use of MgO boards with their renders, as per their "red list, following the withdrawal of LABC, NHBC and their own findings.

Why The Discontinuation of MG0 Boards In Construction?

The discontinuation of MgO use was prompted by a 2017 study from the Technical University of Denmark that revealed moisture damage issues with magnesium oxide boards."and they begin to leak salty water, which is highly corrosive, and leads to moisture and mould problems in wooden members of the structures." leading onto a repair bill "which has had detrimental consequences, such as an expected cost of repair of around 2 billion DKK." when converting into todays value in GBP the cost is in excess of £300million (three hundred million pounds).

- Reference: https://www.sciencedirect.com/science/article/pii/S1876610217349378

Concerns were raised down under, when both School of Science and Engineering and College of Engineering, Australia had "raise questions about the appropriateness of magnesium oxide boards" following their study of hygrothermal performance of magnesium oxide (MgO) boards.

- Reference: https://www.sciencedirect.com/science/article/abs/pii/S0950061821021875

Followed by a released finding that shows "Magnesium oxide (MgO) wallboards have been linked to damages reported globally and within Australia. These damages include dampness, cracking, and accelerated corrosion of contacting metal fixtures."

- Reference: LINK

Effects of MG0 board in Steel Structures?

Credit to: School of Science and Engineering, University of the Sunshine Coast, Maroochydore, Qld 4556, Australia

The image above shows Zinc covering of the steel profile is corroded as a result of direct contact with salty leaked water from the adjacent MgO-board

The effect of using MgO boards caused the "Salt from MgO-boards is highly corrosive on metal fasteners and profiles. Zink flashings of 0.8 mm corrode in 1- 2 years. Electro galvanized steel profiles, nails and screws will corrode through to the steel in 1-2 years. Aluminum alloys have different resistance against corrosion and the best alloys have been seen undamaged for 2-3 years. Stainless steel of A2 and A4 can be used without problems. When MgO boards have been sitting on a wooden structure, MgCl2 salt will have been absorbed by the wood, which is then corrosive to metallic fasteners other that stainless steel"

Reference: https://www.sciencedirect.com/science/article/pii/S1876610217349378

Alternatives to MgO Boards?

Fibre Cement is a preferred alternative to MgO, recommended by leading render manufacturers and the LABC. It is a versatile solution used as a sheathing, render carrier, and tile backer board. Fibre Cement is durable, fire-resistant, termite-resistant, moisture-resistant, and rot-resistant, making it low-maintenance and long-lasting. This makes it suitable for use in areas prone to natural disasters and environmental hazards.

The information in this blog post is based on third-party references and sources we believe to be reliable. However, we make no guarantees regarding the accuracy, completeness, or reliability of the content. The summary provided is for general informational purposes only and should not be considered as professional advice. Readers are encouraged to verify any information before relying on it for their own purposes.

Fibre cement vs MGO

alex@lumifymedia.co.uk (Alex Twigg) — Tue, 13 Dec 2022 13:33:37 GMT

Fibre Cement vs MgO Boards

In this blog we will be covering, the fundamentals of fibre cement then into the the similarities and differences between Fibre Cement and MgO.

What Is Fibre Cement?

Fibre cement is a building material that is made from a mix of cement, sand, and cellulose fibres. It is strong, durable, and versatile, making it suitable for a wide range of applications, including wall cladding , roofing, flooring and for wetrooms . It is also resistant to weathering, rot, and insect damage, making it a popular choice for both residential and commercial construction. Fibre cement is also non-combustible and can be used in fire-rated applications, making it an ideal choice for fire-resistant construction.

Advantages of Fibre Cement Vs MgO

Fibre cement is a more durable and long-lasting material than MgO boards, making it less likely to warp, crack, or break over time. It is also resistant to weathering, rot, and insect damage, making it a better choice for outdoor or wet environments. Fibre cement is also non-combustible and can be used in fire-rated applications, whereas MgO boards are combustible and should not be used in fire-resistant construction. Fibre cement is also available in a wider range of colours, textures, and styles, giving you more design options to choose from. Overall, fibre cement is a more versatile, durable, and reliable material for building applications than MgO boards.

Benefits of Fibre cement vs MGO

There are several benefits to using fibre cement over MgO boards in building applications that include:

Durability: Fibre cement is more durable and resistant to damage than MGO. It is also fireproof and does not rot, corrode or decay.
Strength: Fibre cement is stronger and more rigid than MGO. It can withstand extreme temperatures and high moisture levels without warping or splitting.
Versatility: Fibre cement is versatile and can be used in a variety of applications, such as exterior siding, roofing, flooring, and decking.
Cost: Fibre cement is less expensive than MGO, making it a more budget-friendly option for many projects.
Maintenance: Fibre cement requires minimal maintenance and can be painted or stained to match any decor

Cons Of Fibre Cement?

However like anything, not everything is perfect. Fibre cement does come with some cons. Here are a handful of potential disadvantages to using fibre cement, including:

Weight: Fibre cement is a relatively heavy material. An example of this is our Cembloc board which averages in at 1350kg/m3 meaning a 1000mm x 1000mm x 10mm board would weigh in at 13.5kg per board, which may make it potentially difficult to install and may require additional support.
Installation: Installing fibre cement siding's require specialised tools and skills.
Differences: This point is an interesting one, and sometimes gives fibre cement a bad reputation. The vast amount of fibre cement products on the market range from Grade I to Grade III. The later being often compared to weetabix. In these instances, fibre cement is pushed aside for other building material alternatives due to the Grade III quality, but this is by all means a false reality of how fibre cement should be. That is why, we highly recommend talking to a fibre cement specialist prior to any order as it may not be what you're expecting.

For more information about Fibre Cement and its potential benefits in your application get in touch with the Cembloc team, where we can guide you in the right direction.

Why fibre cement is the future of construction"

alex@lumifymedia.co.uk (Alex Twigg) — Mon, 12 Dec 2022 16:00:00 GMT

Is fibre cement is the future of construction? And If so, Why?

Fiber cement is quickly becoming one of the most popular building materials in the construction industry. This versatile and durable material offers a range of benefits that make it an ideal choice for any building project. In this post, we will discuss the top reasons to choose fibre cement for your construction needs.

First and foremost, fibre cement is known for its durability and longevity. Unlike other building materials, fibre cement is resistant to fire, rot, and pests, making it a low-maintenance option that will last for years to come. Additionally, fibre cement is moisture-resistant, which makes it an ideal choice for damp or humid environments, such as wet rooms.

Another benefit of fibre cement is its cost-effectiveness. It is generally less expensive than other building materials, such as brick or stone, and it can be easily molded and shaped to fit any design or project. This means that you can save money on your building project without sacrificing quality or performance.

In addition to its durability and cost-effectiveness, fibre cement is also environmentally friendly. It is made from a mixture of cement, sand, and cellulose fibres, which are derived from recycled wood and paper products. This means that it is a sustainable building material that reduces waste and minimises the environmental impact of construction.

Finally, fibre cement is versatile and can be used in a variety of building applications. It is commonly used as a cladding material on the exterior of buildings, but it can also be used for roofs, floors, walls, and other structural elements. This means that it is a versatile material that can be used in both residential and commercial construction projects.

In conclusion, fibre cement is a durable, cost-effective, and environmentally friendly building material that is well-suited for any construction project. Its versatility and performance make it an ideal choice for both residential and commercial construction. If you are considering using fibre cement for your next building project, be sure to contact a reputable supplier to ensure that you get the best quality materials at the most competitive prices. As the quality of fibre cement is apparent across various sellers of the material, with some sellers opting for more fibres opposed to cement and so forth.

Benefits of fibre cement decking

Sat, 16 Apr 2022 14:13:01 GMT

Fibre Cement Decking

vs

Plastic PVC Decking vs Timber Decking .

Life's Simplicity

Generally people enjoy lifestyle simplicity. Taking the dog on a long walk and spending time with friends and family. To do this effectively, and providing the UK weather permits, this includes spending time outdoors in the fresh air, maybe in the garden, on the decking, terrace area or balcony.

Unfortunately the outdoor lifestyle here in the UK is minimal to say the least, lets face it...it rain a lot, more than we want. This rain, the wind, the sun and for the more extreme, snow and frost are all elements out of our control that often take their toll on traditional timber decking materials, causing rot, warping, twisting, splitting, fading that all put together can create a very unsightly dangerous and slippery surface. It's fact that traditional timber decks require serious and regular maintenance. Instead of enjoying your free time, you're outside maintaining your timber decking, maybe re-painting, re-varnishing, replacing old warped pieces with new pieces, and on top of all that then you have the drying time to be able to use it again. Your valuable free time has disappeared...

So what do you do? Look for an 'upgrade' maybe look to an alternate to wood decking, maybe composite PVC planks...plastic and again not eco friendly. You may soon realise you've made another mistake. Why? Well, aside from the obvious discolouration, given time, PVC can also be extremely slippery and dangerous, more so than timber decking. It's made of plastic, and therefore generally looks and feels like plastic. Lastly, it's longevity of wear and tear is questionable at times.

The answer? Well if you've done your homework you may have come across a fibre cement decking board variant, these are far more durable, a long lasting decking material that can still give you the look and feel of real wood, fibre cement decking will not burn, it's anti-slip, will not twist, split or warp and has longevity with a minimum of 25 years. You've found the perfect decking material.

Realistic and natural looking

Fibre cement decking boards are made in a press mold to give the texture of real wood giving it a realistic looking wood finish. Whilst most composite PVC decking manufacturers also claim the same, the presence of plastic inside the decking also means that the finished deck planks have a very 'distinctive' plastic sheen to them, letting everyone know exactly what your deck is made of, before they even set foot on it.

Unlike composite PVC decking, fibre cement isn’t stamped or pressed from a larger sheet and contains NO plastics giving it great looks and a natural warm feel similar to that of real wood.

Natural wood has its pluses aesthetically however given time, and when left open to the elements it fades in colour, it's surface treatment coat peels or wears off giving added maintenance whereas with fibre cement you can just fix it into position and leave it, it's totally maintenance free.

Durability, standing the test of time

In a time where everything around us is increasing in cost your decided purchase needs to stand the test of time, this should still apply to your choice of decking. Fibre cement decking can certainly offer longevity allowing you a minimum of 25 years of normal wear and tear, certainly in many cases you should want your decking to last as long as you own your home, fibre cement decking provides this longevity. Given the nature of cement, the boards themselves are extremely durable allowing the boards to be used for the majority of structural projects. Fibre cement construction boards are resistant to insects, resistant to moisture, UV stable - some may say, it's got it's factor 50 on. Fibre cement decking is naturally flame resistant and classed as a non-combustible, BBQ on your decking to your hearts content with no worry of fire or damage. Your fibre cement decking can be safely used all year round without the need to worry about putting on any protective coats, sealants and insecticides that are usual for timber treatment on a yearly basis.

Installs Easily

A controversial topic, who knew about that 'extra' box of fasteners and clips? It's too late when you've made your mind up "Don't worry they're spares"...Composite PVC decking is complicated, the amount of clips and fasteners is extensive, this really slows down the installation creating the possibility of you needing to find a tradesman, and quick, to finish the work on your behalf. Fibre cement decking on the other hand installs quickly and easily with no hidden extras, and if you have ever put together a timber deck before you will easily make the switch to fibre cement and won’t be slowed down in the slightest.