Arris Rails
(2 Products)Arris rails are triangular timber beams, typically derived from pressure-treated softwood, essential for constructing traditional closeboard or feather edge fencing. Running horizontally between fence posts, they form the crucial structural framework. Their primary role is to provide robust support and a secure fixing point for the vertical feather edge boards, preventing warping and distributing wind loads effectively. Installation is achieved either by slotting shaped ('ended') rails into morticed posts or by securing plain-ended rails using metal brackets.
What are Arris Rails?
Arris rails are specially cut timber rails, typically featuring a triangular or diamond-shaped profile. This unique shape is achieved by cutting a square timber section diagonally. They are designed to sit neatly between fence posts, creating a solid framework onto which individual feather edge boards or panels are fixed. Some arris rails come with shaped ends (scarfed) designed to fit snugly into morticed fence posts, while others have flat ends for fixing with metal brackets.
Primary Role and Structural Importance
- Fixing Ground: They provide the necessary continuous, stable fixing ground for securing the overlapping vertical feather edge boards using appropriate galvanised nails or screws.
- Load Distribution: Arris rails distribute lateral loads, particularly wind loading, exerted on the fence face across the bay and transfer these forces effectively to the supporting posts.
- Cladding Stability: They are crucial for maintaining the alignment of the feather edge boards, preventing deformation such as warping, twisting, or bowing over the lifespan of the fence.
- System Rigidity: The interconnected system of posts and rails creates a rigid structure capable of withstanding typical environmental stresses.
Applications
- Constructing new feather edge/close board fencing.
- Repairing existing traditional timber fences.
- Providing structural support between fence posts (timber or concrete).
Benefits
- Essential Structural Support: Arris rails provide the crucial horizontal framework for closeboard (feather edge) fences. They connect between posts and provide a solid structure to which the vertical feather edge boards are fixed, ensuring the fence's overall strength and rigidity.
- Designed for Feather Edge: Their triangular profile is specifically shaped to securely hold overlapping feather edge boards, preventing them from twisting or warping over time.
- Enhanced Durability:
- Water Runoff: The sloped top surface of the triangular rail helps rainwater run off efficiently, reducing the amount of moisture sitting on the timber compared to a flat rail, which helps prolong its life.
- Pressure Treatment: Arris rails are typically pressure treated (often to UC3 standard) to resist rot, fungal decay, and insect attacks, making them suitable for long-term outdoor use above ground.
- Strength: The inherent shape provides good rigidity along the length of the rail, effectively distributing wind load and other stresses across the fence bay.
- Versatile Installation: They can be installed using traditional methods (shaping ends to fit into morticed posts) or more modern methods using metal arris rail brackets fixed to plain posts (timber or concrete). This offers flexibility during construction and repair.
- Adaptability: Fences constructed using arris rails and individual feather edge boards can more easily follow the contours of sloping or uneven ground compared to pre-made panels.
- Ease of Maintenance: If part of the fence gets damaged, individual components like the arris rails or feather edge boards can often be replaced without needing to replace an entire fence panel.
- Traditional Aesthetic: They are a key component in creating the classic, robust look of a traditional closeboard or feather edge fence.
Complete Your Fencing Project
Don't forget to browse our complementary fencing supplies, including:
Which Rail is Right for Your Fence?
- Choose Arris Rails if: You are using morticed or notched posts and want the traditional closeboard look with boards fitted between the posts.
- Choose Cant Rails if: You are fixing rails directly to the face of posts and want a continuous run of feather edge boards in front of the posts.
Maintaining Protection: Treating Cut Ends
While pressure treatment protects the bulk of the timber, any cut ends expose untreated wood. It is crucial to apply a suitable end grain preservative to all sawn ends before installation. This seals the timber, preventing moisture ingress and maintaining the integrity of the treatment barrier.
Frequently Asked Arris Rails Questions
How Many Arris Rails Do I Need Per Fence Bay?
The required number depends on the fence height:
- Fences up to 1.2m (approx 4ft) high typically require 2 arris rails per bay (top and bottom).
- Fences above 1.2m up to approx 1.8m-2.1m generally require 3 arris rails per bay (top, middle, and bottom) for adequate support and to prevent board warping.
- Very tall fences may require four rails. Always ensure sufficient support for the feather edge boards.
Can I Use Timber Arris Rails With Concrete Fence Posts?
Yes, absolutely. You can use 'ended' (shaped end) arris rails with concrete morticed posts that have the correct size slots. Alternatively, you can use plain-ended arris rails with concrete morticed posts by employing galvanised mortice adaptor brackets, which fit into the slot and provide a fixing point for the rail.
How Do Arris Rails Differ From Cant Rails?
Arris rails have a triangular profile and are designed primarily to fit into morticed or notched fence posts for traditional closeboard construction. Cant rails have a rectangular profile with a sloped top edge and are usually fixed directly onto the face of fence posts, often used when feather edge boards run continuously in front of the posts
What Are 'Scarfed' or 'Ended' Arris Rails Specifically Designed For?
'Scarfed' or 'ended' refers to arris rails that have their ends pre-shaped into a tenon (a specific cut designed to fit into a slot). These are specifically designed to be used with morticed fence posts (timber or concrete), where the tenon slots directly into the mortice hole for a traditional and secure joint.
