Traditional Fix or Secret Fix Cladding – Which is Right for Your House’s Exterior?

Timber cladding remains a top choice for self builders and renovators, offering natural beauty, great sustainability credentials and versatility in design. Whether you’re aiming for a traditional or modern aesthetic, it brings a warmth and character that few materials can match.

Achieving a high-quality finish, however, depends not only on timber species and profile selection but also on how it’s fixed to the building. All of these factors affect the finished appearance and performance.

Nailing the Basics

Regardless of fixing method, certain principles apply to most wood cladding projects. Timber is hygroscopic, which means that it absorbs and releases moisture based on environmental conditions, expanding and contracting with seasonal changes. To manage this natural movement and avoid issues like cupping or warping, movement gaps must be incorporated into the design to ensure the cladding remains stable and performs as expected over time.

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This project was realised using a traditional-fix system, with the heads unapologetically on show. Aligning fixings with this much precision takes time, patience and skill from quality installers

A breathable membrane is essential for protecting the building envelope, allowing moisture to escape whilst preventing it from penetrating the structure. Most cladding systems need a ventilated cavity, usually created with battens, to promote airflow behind the boards and reduce the risk of decay.

Traditional Fix

The most common fixing method uses nails or screws driven through the face of each timber board into the support battens. The key benefit of this is that the material costs are low, it’s easy to understand and accessible for most installers. High-quality stainless steel fixings – such as Millworks’ MillFix range, designed specifically for cladding applications – are preferred for external use, as these resist the corrosion and staining that can occur with galvanised or coated alternatives.

While traditional fix is simple and reliable, it has drawbacks. Visible fixings can disrupt a clean design, especially in contemporary projects. Plus, improper installation can create points for moisture ingress, which can damage the cladding boards.

Left: MillFix screws feature a small, ornamental countersunk head designed to finish flush with the board surface. Right: Grad x Millworks uses factory-installed, pre-spaced clips to deliver a clean finish and faster installation, thus reducing the cost of skilled labour

Secret Fix

Recently, there’s been a shift in design preferences towards clean, minimalist exteriors. As part of this, open rainscreen cladding profiles have gained popularity. These offer a crisp, linear aesthetic that can be compromised by visible screw heads, making traditional fixing less suitable.

Secret fix systems have therefore emerged as the preferred method for achieving a clean facade. These conceal the fixings entirely, using clips or interlocking profiles to secure the boards without visible fasteners. Beyond improving aesthetics, they also enhance performance by reducing moisture ingress points and helping to maintain the integrity of timber finishes.

This extension has been finished with Millworks’ Thermowood cladding. Sourced from Nordic sawmills, Millworks’ Thermowood is thermally modified, enhancing the wood’s natural attributes for a highly-durable exterior

Merging Millworks’ timber expertise with Grad’s clip technology, the Grad x Millworks system delivers on all fronts. Cladding boards are grooved on the reverse and mounted to aluminium rails using pre-fitted clips to ensure consistent spacing between boards and automatically allow for movement. This eliminates the need for gap setting – a key detail that must be undertaken manually with traditional-fix methods – and makes it easy to realise complex designs with precision and efficiency.

With no visible screws to align or fix, the system also speeds up installation, reducing on site labour. Plus, the Grad rails incorporate built-in ventilation, so there’s no need for counter-battens, delivering a fixing system that’s as durable as your timber cladding.

Which is Best?

While secret fix systems may involve higher upfront costs and more detailed specification, their aesthetic and technical advantages are significant. Ultimately, the fixing method should align with your design goals and the technical demands of your build. Understanding your options early and consulting with your architect, installer or timber supplier will help to ensure your cladding performs beautifully and lasts for years to come.

Steven Newman Steven Newman is the founder of Millworks. He shapes the company’s values with a passion for research, development and long-term investment. Through prioritising innovation and quality, Millworks combines advanced engineering with strong knowledge of timber behaviour, delivering high-performance solutions that support self builders and renovators. For guidance on selecting the best cladding and installation system for your project, get in touch with the team by heading to the Millworks website or call 01223 967733.