Arris Rail Brackets: Sizes, Types and How to Fit Them
Choose an arris rail bracket by the post connection first, then check its dimensions against the rail. A long bracket fixed to a timber post, a handed support and a mortice adaptor for a concrete post make different connections, even when they are all sold as arris rail brackets.
This guide explains the types, the sizes in our range and the checks to make before fitting or repairing feather edge fencing.
What is an arris rail bracket?
An arris rail is the triangular horizontal timber behind a feather edge fence. Its bracket connects the rail to a post, providing fixing positions around that shaped rail. A bracket for an arris rail is different from a clip holding a complete fence panel or a shoe supporting the bottom of a fence post.
Which type do you need?
| Bracket type | Typical connection | Check before buying |
|---|---|---|
| Standard timber-post rail bracket | Arris rail to a timber fence post; suitable designs can also repair a failed rail connection. | Rail profile, bracket length and sound timber at the fixing positions. |
| Handed support brackets | Separate left- and right-hand components for the intended rail-to-post arrangement. | Which hand is required at each position and how many components are supplied. |
| Mortice adaptor | Timber arris rail to an existing suitable mortice in a concrete post. | Post opening, projecting adaptor end and actual rail dimensions. |
Standard brackets for timber posts
These formed brackets fix to the timber rail and post. We list 100mm, 225mm and 300mm timber-post arris rail brackets. Compare the particular design and available fixing area. A longer bracket is not, by itself, a published higher load rating.
Handed support pairs
Our TIMCO ARBS support brackets measure 90 × 60 × 60mm and are supplied as one left-hand and one right-hand part. TIMCO specifies these galvanised carbon-steel supports for fitting arris rails to timber posts or repairing a rail-to-post connection. Do not confuse a pair of components with a single bracket when planning quantities.
Mortice brackets for concrete posts
The Fixings Direct 200mm mortice arris rail bracket uses a projecting end that enters a suitable existing post mortice. The bracket then fixes to the timber rail. It is not a universal fitting for every concrete post: a panel slot and a rail mortice are different details.
Arris rail bracket sizes explained
| Product | Listed size | Connection to check |
|---|---|---|
| Short timber-post bracket | 100 × 60 × 60mm | Rail profile and available fixing area |
| Timber-post bracket | 225 × 60 × 60mm | Rail profile and available fixing area |
| Long timber-post bracket | 300 × 60 × 60mm | Rail profile and available fixing area |
| TIMCO ARBS handed support | 90 × 60 × 60mm | Handed arrangement; sold as a pair |
| Concrete-post mortice adaptor | 200 × 62 × 62mm | Existing mortice and adaptor fit |
These are bracket dimensions, not a guaranteed compatible timber size. A “60mm” dimension in a bracket listing does not mean that every rail described as 60mm will fit. Timber may be sold by nominal size; measure the actual triangular section, the bracket's fixing faces and the post detail.
For a replacement, take three measurements: the rail section where the bracket sits, the space available along the rail, and the post fixing surface or mortice opening. Compare the product drawing where one is available. Different manufacturers' similarly named brackets can have different lengths and hole arrangements.
How to fit an arris rail bracket to a timber post
- Inspect the connection. Check that the post and rail are sound where the fixings will enter. Replace a decayed rail end rather than relying on a bracket over soft timber.
- Offer up the correct bracket. Seat it against the rail profile and post, with the rail at its intended height and alignment. Check the handed part where applicable.
- Support the rail while positioning. Mark the fixing positions and confirm the fasteners will enter sound timber without fouling another connection.
- Fit the specified fasteners. Use the bracket's intended fixing holes and suitable outdoor timber fixings. Follow the particular bracket and fastener guidance on diameter, length, penetration and pilot holes.
- Check the finished joint. The bracket should seat properly, with the rail aligned and the fixings secure before the remaining fence work is completed.
For TIMCO ARBS specifically, the supplier recommends a 4mm screw diameter. That is not a universal screw specification for every bracket in the table, and it does not determine the screw length for your timber.
How to use a mortice arris rail bracket with a concrete post
- Check that the existing concrete post and mortice are sound and that the opening matches the adaptor.
- Trial-fit the projecting end into the existing opening. Check that the bracket can seat without being forced and that the rail will sit in the correct position.
- Support and align the replacement rail, then fix the bracket to the timber through its intended holes using the specified suitable fasteners.
- Check the engagement at the post and the finished rail connection before completing the fence.
This method depends on a suitable existing mortice. It is not an instruction to drill a new opening in a concrete post or to fit a timber-post bracket into a panel slot.
How many brackets should you order?
Count the actual rail-end connections, then check the fitting arrangement and pack contents. For example, two bays with three separate rails per bay have six rails and twelve rail ends. The required number of brackets or handed parts depends on how those ends connect; twelve rail ends does not automatically mean twelve pairs.
Our standard and mortice products offer different pack choices. Compare the live product price and quantity supplied rather than assuming a supplier's trade-box quantity is the quantity in your selected pack.
Common questions
Can I use a timber-post bracket on a concrete post?
Only where that exact bracket has an appropriate specified concrete-post connection. For an existing morticed post, compare a purpose-made mortice adaptor. Do not select a timber fixing arrangement just because the bracket appears to sit against the concrete.
Will a longer bracket repair any broken arris rail?
No. The remaining timber, the location of the break and the fixing detail matter. A bracket cannot restore rotten timber or stabilise a failed post. Our fence repair guide helps identify which part has failed.
Are arris rail brackets the same as fence panel clips?
No. Rail brackets connect individual rails to posts. Panel clips and security brackets retain a complete panel in their intended arrangement. See our fence bracket types guide for the broader comparison.
Ready to choose? Compare our fence brackets, check the actual rail and post measurements, and select the required product and pack quantity.
Product dimensions and supplier information checked on 12 November 2026. The table identifies current listed sizes; use the exact product specification for fit and fixing requirements.
