How to Prepare Walls for Hygienic Cladding Installation

How to Prepare Walls for Hygienic Cladding Installation

October 25, 2024

When it comes to the installation of hygienic cladding, wall preparation is not just a crucial step – it’s the foundation for a successful project. Reading this article will inform you how to prepare walls for hygienic cladding Installation.

At Goss, we understand that properly preparing the substrate is key to ensuring the longevity and effectiveness of cladding installations. Poorly prepared walls can lead to a host of issues, including adhesive failure, de-lamination, and uneven surfaces, all of which compromise the integrity of the cladding. 

These problems not only undermine the hygienic environment that cladding is designed to maintain, but can also add significant time and cost to your project. Addressing issues with poorly prepared walls often requires rework, which can delay subsequent trades, disrupt the project timeline, and inflate costs due to the need for additional materials and labour.

By following our detailed preparation guidelines, you can avoid these pitfalls, ensuring a smooth installation process that stays on schedule and within budget.

Why is it necessary to prepare walls before installing hygienic cladding?

Proper wall preparation is essential because it ensures that the cladding adheres correctly and remains secure over time. If walls are not adequately prepared, the adhesive used to bond the cladding may fail, leading to de-lamination and gaps between panels. 

These issues not only compromise the hygienic integrity of the environment but also require costly and time-consuming repairs. Any delay in addressing these problems can hold up other trades, such as plumbing, electrical, or finishing work, potentially causing a cascading effect on the overall project timeline and budget.

General Wall Preparation Guidelines

What are the general requirements for wall preparation before cladding installation?

All wall surfaces must meet the following criteria to ensure a strong, durable bond between the cladding and the substrate:

Soundness: The substrate must be stable and free of loose material. If the substrate is not sound, the cladding could shift or detach, leading to structural failures that could require the entire installation to be redone.

Dryness: The moisture content should be no more than 14%. High moisture levels can interfere with adhesive curing, leading to weak bonds and potential de-lamination, which will incur additional labour and materials to fix.

Cleanliness: The surface must be dust-free. Dust can act as a barrier between the adhesive and the wall, weakening the bond and leading to installation issues that will need rectifying, delaying other trades and increasing costs. Porous or dusty surfaces should be treated with a PVA (polyvinyl acetate) solution, diluted 1:10 with water. This primer creates a suitable surface for adhesive bonding, ensuring that the cladding installation can proceed without unexpected interruptions.

Specific Wall Types and Their Preparation

How should existing tiled surfaces be prepared?

Tiled surfaces require careful preparation to ensure that the cladding adheres properly:

Degrease: Thoroughly clean the tiles to remove any grease or grime, as contaminants can prevent the adhesive from forming a strong bond.

Rinse and Dry: Rinse with clean water and allow the surface to dry completely. Any remaining moisture can weaken the adhesive, leading to future failures.

Check Bonding: Ensure all tiles are securely bonded; fill any voids to create a smooth surface.

Note: Tiled surfaces are generally unsuitable for welded joint applications unless prepared by specialists. If the surface isn’t adequately prepared, the time spent fixing these issues can delay the installation, increasing labour costs and pushing back the schedule for other trades waiting to complete their work.

What is the correct preparation for plasterboard?

Plasterboard surfaces must be prepared to ensure they provide a stable and even base for cladding:

Flush Fill Joints: All joints must be flush filled to prevent ridges or uneven surfaces that could cause cladding panels to sit improperly, leading to visible defects that may require rework.

Countersink Fixings: Any fixings must be countersunk to avoid protrusions that could cause the cladding to bulge or warp, requiring time-consuming adjustments.

Prime Dusty Surfaces: Use a PVA solution to prime any dusty areas. This ensures that the adhesive bonds effectively, preventing failures that could halt the project and increase costs.

Failing to properly prepare plasterboard can lead to uneven cladding installation, requiring removal and reinstallation, which would further disrupt the project timeline and inflate the budget.

What steps should be taken when preparing plywood?

Preparing plywood correctly is essential to prevent issues during cladding installation:

Flush Joints: Ensure all joints are flush to avoid creating an uneven surface that could cause alignment issues during cladding installation.

Countersink Fixings: All fixings must be countersunk to prevent any protrusions that could interfere with the cladding’s adherence, leading to bulges that require correction.

Prime Surface: Prime dusty surfaces with a PVA solution to ensure a strong adhesive bond. Improper preparation of plywood can lead to visible defects in the cladding that require rework, delaying the project and increasing costs due to the need for additional materials and labour.

How should plaster be prepared?

A: Plaster surfaces require specific preparation to ensure they provide an adequate base for cladding:

Prime Surface: Apply a PVA solution to the plaster to ensure the adhesive bonds properly, preventing de-lamination and subsequent delays in the project.

Skim and Hardwall: Ensure the plaster conforms to BS5492, the Code of Practice for internal plastering (1990). This ensures that the surface is smooth and stable, providing a reliable base for cladding.

Avoid Incompatible Plasters: Pink lightweight plasters are not recommended, and a scratch coat finish is unacceptable as they can weaken the bond and lead to cladding failure.

Incorrectly prepared plaster surfaces can cause the cladding to fail, necessitating costly repairs and delays that will impact other trades waiting to complete their work.

What is required for preparing render?

Render surfaces must be prepared to provide a suitable substrate for cladding:

Finish: Sand and cement render should have a steel trowel finish to ensure a smooth and even surface for the cladding to adhere to. A rough finish could cause uneven cladding installation, leading to delays.

Prime Surface: Apply a PVA solution to ensure a strong bond between the render and the adhesive.

Inappropriate Finishes: Avoid using a scratch coat finish, as it does not provide the smooth surface required for successful cladding installation.

Improper preparation of render can lead to significant installation issues that may require reworking the surface, causing delays and increased costs.

What should be done to prepare brick or block work?

Brick or block work needs to be carefully prepared to avoid complications during cladding installation:

Evenness: The surface must be fair faced, even, and free from protrusions or voids to prevent cladding from being installed unevenly, which could lead to costly adjustments.

Straightness: The surface should be straight, within 3mm over a 2m straightedge, to ensure that the cladding sits correctly. Deviations can cause installation issues that delay the project.

Prime Surface: Apply a PVA solution to ensure proper adhesive bonding.

Note: Brick or block work is not suitable for welded joint applications. If these surfaces are not properly prepared, reworking them can significantly delay the installation process and push back other trades.

How should painted surfaces be prepared?

Painted surfaces require thorough preparation to ensure cladding adhesion:

Degrease: Thoroughly degrease the surface to remove contaminants that could weaken the adhesive bond, leading to future cladding failures.

Rinse and Dry: Rinse with clean water and allow to dry completely to prevent moisture from interfering with the adhesive curing process.

Remove Loose Paint: Remove any loose or flaking paint to ensure the cladding adheres to a solid, stable surface.

Prime Exposed Surfaces: Prime with a PVA solution if required to create a suitable base for the adhesive.

Failure to properly prepare painted surfaces can result in cladding detachment, necessitating repairs that will delay the project and increase costs.

What is the process for preparing papered surfaces?

Properly preparing papered surfaces is crucial to avoid complications during cladding installation:

Remove Wallpaper: All wallpaper must be removed to expose the substrate, ensuring that the adhesive bonds directly to the wall rather than a temporary surface.

Clean and Prepare: The exposed surface must be cleaned, with voids filled and porous areas primed with a PVA solution to ensure the cladding adheres properly. If wallpaper is not removed, it can cause the cladding to detach, requiring reinstallation that will disrupt the project timeline and budget.

How should concave or convex walls be dealt with?

Concave or convex walls present a unique challenge for installation of hygienic wall cladding. Thermoforming allows the cladding to be shaped to follow the curvature of the wall, but this process may still leave voids between the cladding panels and the substrate if the surface is not adequately squared up.

To address these voids, additional resin glue will need to be applied into the gaps to help fill them. However, even with this extra step, there’s no guarantee that all voids will be completely eliminated, especially in cases where the wall is significantly concave or convex. 

This can impact the overall integrity and longevity of the cladding installation, as voids can create weak points that may lead to adhesive failure or de-lamination over time.

To mitigate these issues, it’s recommended that the walls be squared up as much as possible before the cladding installation begins. This will help reduce the likelihood of voids and ensure a more secure and durable cladding installation, ultimately saving time and money in the long run.

Ensuring the Correct Temperature for Installation

What is the importance of maintaining a specific temperature during the installation process?

The ambient temperature, including that of the substrate, is critical for the success of the adhesive curing process. The room must maintain a minimum temperature of 14˚C for at least 24 hours before and after the installation. 

Failure to maintain this temperature can prevent the adhesive from curing correctly, leading to de-lamination, which would require reinstallation. This can result in significant delays to the project, especially if other trades are scheduled to begin work immediately after cladding installation and will also increase costs due to the need for additional materials and labour.

In Summary

Preparing walls for hygienic cladding installation is an essential step that should not be overlooked. By following the guidelines detailed above, you ensure that the substrate is in optimal condition for the application of cladding, guaranteeing both its quality and longevity.

George Goss

AUTHOR: George Goss

George Goss is the owner of Goss Environmental Coatings. For over 30 years they’ve been providing hygienic wall cladding, hygienic coatings and other hygienic solutions to clients including the NHS, Boots, The British Army and many others.

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