The Self-Drilling Screw is the primary fastening element in the ULAMEX modern fencing system, engineered to connect aluminum and steel fence components quickly and securely without pre-drilling. Every joint in a modern horizontal slat fence — from slat-to-bracket connections and cross-rail-to-post fixings to accessory mounting points — relies on the performance of its fasteners. A poorly chosen screw can compromise an entire fence installation: stripped threads, corrosion streaks, or visible silver heads that undermine an otherwise premium anthracite finish. The ULAMEX self-drilling screw eliminates each of these failure points through a purpose-built design combining a hardened drill-point tip, a stainless steel A2 body, and a colour-matched painted head in RAL 7016. Whether you are assembling a single residential privacy fence or supplying hardware for dozens of commercial projects across Europe, this screw delivers consistent, reliable performance in every application.
Technical Specifications
The self-drilling screw is available in three sizes, each optimised for a specific connection type within the fence structure:
| Size | Primary Application | Material Penetration |
|---|---|---|
| 4.8 × 19 mm | Slat-to-bracket connections, light accessories | Aluminum up to 2 mm |
| 5.5 × 25 mm | Standard cross-rail-to-post connections, mounting angle fixings | Aluminum up to 3 mm, steel up to 1.5 mm |
| 5.5 × 32 mm | Heavy-duty connections through thicker profiles, steel-to-steel joints | Aluminum up to 3 mm, steel up to 2 mm |
The screw body is manufactured from austenitic stainless steel grade A2 (AISI 304), providing excellent resistance to atmospheric corrosion, salt spray, and humidity — the three main degradation factors in outdoor fence installations. The hardened carbon steel drill-point tip is engineered to cut cleanly through aluminum alloy EN AW-6063 T6 profiles without deformation, burring, or swarf accumulation. Thread geometry follows a coarse-pitch design that grips firmly in thin-walled aluminum sections, preventing loosening under thermal expansion cycles and wind-induced vibration loads that are typical for exposed fence structures.
The hex-washer head incorporates an integrated EPDM sealing washer that compresses against the profile surface upon tightening, creating a weather-tight seal that prevents moisture ingress at the screw penetration point. The head is coated with a baked-on polyester paint colour-matched to the fence system finish, ensuring long-term colour stability without flaking or fading under UV exposure.
Installation Guide
One of the key advantages of self-drilling screws is their ability to eliminate the separate drilling step that traditional screws and bolts require. Installation follows a straightforward process:
- Position the components to be joined (e.g. cross-rail against post, or slat against mounting angle).
- Place the screw tip against the outer profile surface at the marked fixing point.
- Drive the screw using a cordless drill/driver with a hex-socket bit at 1,500–2,500 RPM. The hardened tip drills its own pilot hole, taps the thread, and clamps the components together in a single continuous operation.
- Stop driving once the EPDM washer compresses flush against the surface. Do not over-torque — excessive force can strip the thread in thin-walled aluminum sections.
Recommended torque setting: 3.5–5.0 Nm for aluminum profiles, 5.0–7.0 Nm for steel components. Using a drill with adjustable clutch settings prevents over-driving. For installations involving the 80×80 mm system post, position screws at least 15 mm from the profile edge to avoid splitting the aluminum wall.
In cold-weather installations (below 5 °C), pre-warming aluminum components is not required, but reducing drill speed to 1,200 RPM improves screw engagement and reduces the risk of thread stripping in cold, brittle material.
Material and Corrosion Protection
Corrosion is the primary enemy of outdoor fasteners. The ULAMEX self-drilling screw addresses this through a dual-material construction: the body and upper thread section are stainless steel A2, which provides a minimum of 500 hours salt spray resistance (per ISO 9227) without surface deterioration. The drill-point tip uses hardened carbon steel for cutting performance — this small exposed area is protected by a zinc-nickel coating that prevents galvanic corrosion at the bimetallic junction between the tip and the stainless body.
The colour-matched head coating is a UV-stabilised polyester powder paint, applied and cured at 200 °C to bond permanently to the stainless steel substrate. This finish resists chipping, flaking, and colour fading for 10+ years in Central European climates, ensuring the screw heads remain visually indistinguishable from the surrounding powder-coated fence profiles throughout the life of the installation.
For environments with elevated corrosion risk — coastal installations, industrial zones, or swimming pool surrounds — ULAMEX also supplies A4 (AISI 316) marine-grade stainless steel self-drilling screws on request. These offer superior resistance to chloride-induced pitting and crevice corrosion.
System Compatibility
The self-drilling screw is designed as a universal fastener within the ULAMEX modern fencing system and is compatible with the full range of system components:
- Aluminum fence profiles — horizontal slats, cross-rails, cover strips
- System posts 80×80 mm — post-to-rail and post-to-bracket connections
- Mounting angles 15×15 mm — angle-to-post and angle-to-rail fixings
- All fence accessories — post caps, base plates, gate hardware mounting
Beyond the modern fencing system, the self-drilling screw is equally effective for galvanized steel panel fences, carport cladding, and general aluminum or thin-gauge steel construction applications. The 5.5×32 mm size is particularly suited for connections involving hot-dip galvanized steel sections up to 2 mm wall thickness.
Design Integration
In modern fence design, the fastener should be invisible — or at minimum, should blend seamlessly with the surrounding surface. The ULAMEX self-drilling screw achieves this through colour-matched heads available in four standard RAL finishes:
- RAL 7016 (Anthracite Grey) — the dominant colour in contemporary European fence design, matching ULAMEX standard profiles
- RAL 9005 (Jet Black) — for high-contrast modern installations
- RAL 7035 (Light Grey) — for lighter, Scandinavian-inspired fence designs
- RAL 9006 (White Aluminium) — for silver/metallic finishes and raw aluminum systems
The low-profile hex-washer head sits close to the profile surface, minimising shadow lines and visual protrusion. In concealed mounting positions — such as screw fixings behind slats or inside post cavities — the colour-matched head provides an additional layer of visual consistency should any part of the fastener become visible from certain angles. This attention to detail distinguishes a professionally specified fence installation from one assembled with generic hardware-store screws.
For projects requiring custom RAL colours, ULAMEX can supply screws with heads painted to match any standard RAL shade. Minimum order quantities apply for custom colours — contact us with your project specifications.
Quantity Planning and Ordering
Accurate screw quantity planning prevents project delays caused by mid-installation shortages. Use the following guide as a starting point:
| Fence Component | Screw Size | Qty per Connection Point |
|---|---|---|
| Slat to mounting angle | 4.8 × 19 mm | 1–2 screws |
| Mounting angle to post | 5.5 × 25 mm | 2 screws |
| Cross-rail to post | 5.5 × 25 mm | 2–3 screws |
| Heavy-duty bracket | 5.5 × 32 mm | 2–4 screws |
Example calculation: A 20-metre privacy fence at 2 m height with 10 mm slat spacing, three cross-rails per bay, and posts at 2.5 m centres requires approximately 350–450 self-drilling screws across all sizes. We recommend ordering 10–15 % surplus to account for misdrives and test fittings.
Self-drilling screws are supplied in wholesale packaging:
- Box of 100 pcs — small projects, sample orders
- Box of 250 pcs — standard residential fence installations
- Box of 500 pcs — commercial projects, multi-site contractors
All packaging is clearly labelled with size, material grade, RAL colour code, and batch number for quality traceability. Request a quote for project-specific quantities and mixed-size pallet orders.
Why Choose ULAMEX
ULAMEX has supplied steel and aluminum products to professional contractors and distributors across Europe since 1988. Every component in our modern fencing system — including fasteners — is sourced and quality-controlled to meet the standards expected in the DACH market and beyond. Our self-drilling screws are manufactured under EN 1090 and ISO 3834 certification, ensuring consistent material quality, dimensional accuracy, and corrosion performance across every production batch. As a single-source supplier of profiles, posts, accessories, and fasteners, we eliminate the compatibility risks and logistics overhead that come with sourcing components from multiple vendors. One order, one shipment, one point of accountability.
Frequently Asked Questions
Do self-drilling screws require pre-drilling into aluminum fence profiles?
No. The hardened drill-point tip cuts its own pilot hole through aluminum profiles up to 3 mm wall thickness and steel up to 2 mm in a single operation. Simply position the screw, drive with a cordless drill at 1,500–2,500 RPM, and the screw drills, taps, and fastens in one continuous motion. This eliminates the need for a separate drill bit, reduces installation time by approximately 40 %, and prevents the alignment errors that can occur when pre-drilled holes do not line up precisely.
What is the difference between A2 stainless steel and bi-metal self-drilling screws?
A2 stainless steel screws (standard supply) feature a hardened carbon steel drill tip bonded to an A2 stainless body. They are optimised for aluminum-to-aluminum and aluminum-to-thin-steel connections. Bi-metal self-drilling screws have a more aggressive carbon steel tip designed for thicker steel substrates (up to 2 mm) and steel-to-steel connections. Both types offer the same corrosion resistance in the exposed head and body section. For most modern fencing system applications, the standard A2 screw is sufficient. Bi-metal screws are recommended when connecting to galvanized steel posts or structural steel sections.
Are colour-matched screw heads available in colours other than RAL 7016?
Yes. In addition to RAL 7016 (anthracite), we stock self-drilling screws with heads in RAL 9005 (jet black), RAL 7035 (light grey), and RAL 9006 (white aluminium). Custom RAL colours can be produced for wholesale orders with a minimum quantity — contact us for lead times and pricing. The colour coating is a UV-stabilised baked polyester that resists fading and chipping for over 10 years in outdoor exposure.
How many self-drilling screws do I need per metre of fence?
The quantity depends on fence height, slat spacing, and the number of cross-rails. As a general guide: a 2 m high privacy fence with three cross-rails and slats at 10 mm spacing requires approximately 18–22 screws per running metre (across all sizes). For a precise calculation tailored to your project dimensions, request a quote and our technical team will provide a detailed bill of materials including all screw sizes and quantities.