Roofing Battens – Metal vs Timber

The Pros and Cons of Reusing Metal Roofing Battens: A Comprehensive Guide

When it comes to roof replacements and re-roofing projects, one aspect that often gets overlooked is the type of battens used. Roofing battens play a crucial role in supporting the roof sheeting and ensuring the structural integrity of the entire roofing system. While timber battens have traditionally been the norm in roofing construction, metal battens have gained popularity in recent years due to their durability, strength, and versatility. In this blog post, we will explore the pros and cons of reusing metal roofing battens and compare them to timber battens. Additionally, we will examine the requirements of AS1684.2 (the Australian Standard for residential timber-framed construction) and provide insights into batten spacings and their implications.

What Are Roofing Battens?

Roof battens are horizontal strips that support roof sheeting (such as metal or tile roofing) in both residential and commercial building projects. Battens act as a framework that holds the roofing materials securely in place, preventing them from moving due to wind or external forces. Traditionally, timber battens were commonly used for this purpose, but in recent years, metal battens—typically made from steel or aluminum—have become an increasingly popular alternative.

While re-roofing or replacing a roof, the decision to reuse metal battens can save both time and money. However, it’s important to consider the pros and cons of this approach, especially when comparing metal battens to their timber counterparts.

Timber Battens vs. Metal Battens: A Comparison

When discussing the pros and cons of reusing metal battens, it’s important to compare them to timber battens, which have been the traditional choice in the industry for many years. Both materials have their own unique set of benefits and limitations, and the choice of which to use will depend on various factors such as the type of roof, budget, environmental conditions, and the building’s structural requirements.

Timber Battens: The Traditional Choice

Timber battens have been used in roofing construction for centuries, and they remain a popular choice in many residential and commercial buildings. Traditionally, pine, redwood, or other types of timber have been used as battens, with the species selected based on local availability and cost.

Pros of Timber Battens:

Cost-Effective: Timber battens tend to be more affordable than their metal counterparts. This can be an advantage when working within a tight budget for roofing replacement projects.
Easier to Work With: Timber battens are easier to cut and shape on-site, making them an attractive option for smaller projects or DIY roofing repairs.
Sustainable: Timber is a renewable resource, and when sourced responsibly, it can be considered an eco-friendly material. Timber battens also contribute to the aesthetic appeal of a roof in some architectural designs, especially in traditional or rustic settings.
Natural Insulation: Timber offers some natural insulation properties, which can help improve the energy efficiency of the roof.

Cons of Timber Battens:

Susceptibility to Moisture and Decay: Timber battens are highly vulnerable to moisture, rot, and decay. This can significantly shorten their lifespan, especially in humid climates or areas with frequent rainfall.
Insect Infestation: Timber battens can attract termites and other pests, which can compromise the structural integrity of the battens over time.
Weaker Than Metal: Timber battens are not as strong or durable as metal battens. They are more likely to warp, bend, or split under high stress or adverse weather conditions, such as high winds or heavy snow.
Fire Hazard: Timber is flammable and may pose a fire risk in areas that are prone to wildfires or bushfires.

Metal Battens: The Modern Alternative

In contrast to timber battens, metal battens are made from materials such as galvanized steel, aluminum, or zinc-coated steel. These materials offer a range of advantages in roofing systems, particularly in terms of durability, performance, and resistance to environmental factors.

Pros of Metal Battens:

Durability and Longevity: Metal battens are far more durable than timber battens. They are resistant to moisture, rot, and decay, which makes them an ideal choice for areas with high humidity or coastal environments. Metal battens can also withstand exposure to ultraviolet (UV) light without deteriorating.
Strength and Stability: Metal battens offer superior strength compared to timber. They are less likely to warp, twist, or bend under stress, which makes them suitable for supporting heavy roofing materials such as tiles or corrugated metal sheets. This strength also means that metal battens can typically be spaced further apart, which may reduce the number of battens required.
Fire Resistance: Metal battens are non-combustible, making them a safer option in areas that are prone to wildfires or bushfires.
Pest Resistance: Unlike timber, metal battens are immune to insect infestations, which can compromise the integrity of the roof structure.
Low Maintenance: Metal battens require little maintenance over their lifespan. Unlike timber, they do not need to be treated or replaced frequently due to rot or pest damage.
Sustainability: Many metal battens are made from recycled materials and can be fully recycled at the end of their lifespan. This contributes to reducing the environmental impact of roofing systems.

Cons of Metal Battens:

Cost: Metal battens tend to be more expensive than timber battens. The higher upfront cost may be a barrier for some building owners, particularly those with budget constraints.
Difficult to Work With: While metal battens are strong, they can be harder to cut and shape compared to timber. This can make installation more time-consuming, especially for smaller projects or DIY re-roofing efforts.
Potential for Corrosion: While metal battens are highly resistant to moisture, they can corrode over time if the protective coating (such as galvanization) wears away or if they are exposed to extreme environmental conditions, such as saltwater in coastal areas.
Weight: Metal battens can be heavier than timber battens, especially if made from steel or other dense materials. This can make handling and installation more challenging, especially in areas with structural limitations.

3. Reusing Metal Roofing Battens: Is It a Good Idea?

Reusing metal roofing battens can be a cost-effective and sustainable solution for roofing projects, but it requires careful consideration of several factors to ensure that they still meet safety and structural standards. Below are some of the pros and cons of reusing metal battens.

Pros of Reusing Metal Battens:

Cost Savings: One of the primary reasons to reuse metal battens is cost savings. Reusing existing battens can reduce the overall material costs for the re-roofing project.
Environmental Benefits: By reusing materials, you reduce the environmental impact of manufacturing new battens. This can be especially important for eco-conscious property owners or those involved in sustainable building practices.
Proven Durability: Metal battens, when properly maintained, can last for decades without needing to be replaced. Reusing them ensures that you benefit from their inherent durability, provided they have not been damaged or weakened during the previous roofing installation.
Minimizing Waste: Reusing existing battens helps to minimize construction waste, which is a growing concern in the building industry. By reusing materials, you contribute to the circular economy and reduce landfill waste.

Cons of Reusing Metal Battens:

Potential for Wear and Tear: Over time, metal battens may experience wear, including rusting, corrosion, or physical damage from extreme weather conditions. It is essential to inspect the battens carefully before reusing them to ensure that they are still structurally sound and safe for reuse.
Incompatibility with New Roofing Materials: Depending on the type of roofing material being installed, the existing battens may not be suitable. For instance, the spacing of the battens may need to be adjusted to accommodate the new roofing system, and the condition of the battens may affect the overall integrity of the roof.
Compliance with Australian Standards: The Australian Standard AS1684.2 (Residential Timber-Framed Construction) governs the design and construction of timber framing systems, but it can also influence the requirements for batten spacing in both timber and metal roofing systems. Reused battens must comply with these standards, and their condition must meet the necessary load-bearing requirements, which may require an engineering assessment.

4. Batten Spacing and AS1684.2

Whether you’re using timber or metal battens, the spacing between battens is a critical factor in ensuring the stability of the roof structure. Batten spacing refers to the distance between each batten that supports the roof sheeting. The correct spacing is determined by several factors, including the type of roofing material, the design of the building, and the local environmental conditions (such as wind speed and snow load).

AS1684.2 outlines the standard spacing guidelines for both timber and metal battens based on the roof type, load-bearing capacity, and material specifications. For metal battens, the spacing can generally be wider than for timber battens, as metal battens are stronger and can handle heavier loads.

In general:

Timber Battens: Spacing for timber battens ranges from 600 mm to 900 mm, depending on the type of timber and the roofing material used.
Metal Battens: Metal battens may allow for wider spacing (up to 1200 mm) due to their higher strength and ability to support heavier loads.

It’s essential to consult AS1684.2 and work with a qualified structural engineer to ensure that batten spacings are compliant with the relevant codes and standards.

5. Conclusion

Choosing between timber and metal battens for roofing systems requires careful consideration of the specific needs of the project. Both materials offer distinct advantages and disadvantages, and the decision largely depends on the budget, climate, building design, and desired outcomes. While timber battens are affordable and easy to work with, they come with potential risks such as decay, insect infestation, and fire hazards. On the other hand, metal battens provide superior durability, strength, and fire resistance but may come with a higher initial cost and more complex installation.

Reusing metal roofing battens can be an excellent way to save costs and reduce waste, but it’s important to ensure that the battens are still structurally sound and compliant with relevant standards, such as AS1684.2. Regardless of the type of batten used, proper batten spacing is essential to ensure the safety and longevity of the roof. Always consult with professionals to ensure your roofing system complies with all necessary building codes and standards.