The ULAMEX Adjustable J-Gont Hook Handle is a height-adjustable stainless steel roof hook designed for installing photovoltaic systems on slate and shingle (Gont/Schiefer) roofs. Manufactured from H17 stainless steel (1.4016 / AISI 430), this ferritic stainless hook features a distinctive J-shaped profile that slides beneath the slate or shingle course without disturbing the waterproof overlap. Measuring 30 mm wide, 225 mm long and 4 mm thick, the hook combines a compact footprint with stepless height adjustability, enabling precise alignment of PV mounting rails even on roofs with irregular rafter depths. Fastened with a Torx wood screw directly into the rafter.
Technical Specifications
| Parameter | Value |
|---|---|
| Material | H17 stainless steel (1.4016 / AISI 430), ferritic |
| Height | Adjustable (stepless) |
| Width | 30 mm |
| Length | 225 mm |
| Thickness | 4 mm |
| Fastening | Torx wood screw (into rafter) |
| Finish | Natural stainless (mill finish) |
| Roof type | Slate, shingle, fibre-cement slate |
| Service life | 25+ years |
Installation Guide
Carefully lift or remove the slate/shingle at the planned hook position to expose the rafter beneath. Position the J-gont hook on the rafter with the J-shaped head pointing upward between the slate courses. Adjust the hook height to the required level, ensuring all hooks across the roof will produce a consistent, level mounting rail plane. Pre-drill a pilot hole if required by the timber species, then drive the Torx wood screw through the hook base plate into the rafter. The Torx drive provides high torque transfer and prevents cam-out during fastening. Slide the slate or shingle back into position over the hook body — the slim 30 mm width and J-profile ensure the slate sits flat without lifting or cracking. Attach the PV mounting rail to the hook head. Repeat at each hook position, spacing hooks according to the structural load calculation (typically every 800–1,200 mm along each rail).
Roof Compatibility
The adjustable J-gont hook is designed for natural slate, fibre-cement slate, bituminous shingles and wooden shingle (Gont) roofs. These thin, flat roofing materials require a hook profile that does not lift the covering or break the waterproof overlap pattern. The J-shaped head navigates beneath the overlapping course while the 225 mm length ensures adequate rafter engagement. This hook is particularly well-suited for heritage buildings, mountain architecture, and Northern European traditional construction where slate or shingle roofing is standard. The height-adjustable version is recommended for renovation projects where original timber framing varies from modern standards — rafter depths on older buildings can differ by 15–25 mm across the roof surface. Maximum recommended rafter spacing: 80 cm.
Material Properties — H17 Stainless Steel
H17 (1.4016 / AISI 430) is a ferritic chromium stainless steel with 16–18% chromium content. It delivers good corrosion resistance in atmospheric conditions, with a tensile strength of approximately 450 MPa. H17 is the preferred material for PV roof hooks because it provides sufficient corrosion protection for components concealed beneath the roof covering, at a significantly lower cost than austenitic grades (V2A / 1.4301). The ferritic crystal structure offers superior resistance to stress corrosion cracking — an important advantage in the thermally cycling environment beneath roof tiles and slates. H17 is magnetic, which aids handling and positioning during installation.
Why Choose ULAMEX
ULAMEX has supplied structural steel and stainless steel components for over 35 years, holding EN 1090 certification for the execution of steel and aluminum structures. As a B2B wholesaler, we deliver roof hooks, PV profiles, clamps, fasteners and ballast systems from a single source — reducing procurement complexity and ensuring component compatibility. European delivery with competitive wholesale conditions for solar installers, distributors and EPC contractors.
Frequently Asked Questions
What is the difference between the adjustable and fixed J-gont hook?
The fixed J-gont hook has a set 70 mm height and is ideal for new-build roofs with consistent rafter depths. The adjustable version allows stepless height tuning, making it essential for renovation projects where rafter depths vary across the roof. Both share the same 225 mm length, 30 mm width, 4 mm thickness and H17 stainless steel construction.
Can I install this hook on a natural slate roof without damaging the slates?
Yes. The J-shaped profile is specifically designed to slide beneath the slate overlap without requiring cutting or grinding. The 30 mm width and 4 mm thickness ensure the hook does not lift adjacent slates. Care should be taken when lifting slates to expose the rafter — use a slate ripper tool to avoid cracking the brittle material.
Is H17 stainless steel suitable for use near the coast?
H17 (1.4016) provides adequate corrosion resistance for most inland and suburban locations. For installations within 5 km of the coastline where salt-laden air is a factor, consider upgrading to V2A (1.4301 / AISI 304) or V4A (1.4404 / AISI 316) hooks for enhanced marine corrosion resistance. Contact ULAMEX for availability of coastal-grade hooks.