4.2 x 25mm cement board screws for fixing to timber and thin sheet metal up to 0.6mm. Self-countersinking head, hi-low twin-cut thread, and exterior-grade coating rated to 1,500 hours salt spray. Fire Classification A1.
Cement board to timber screws need to work harder than a standard drywall screw. They have to deal with abrasive board material, the need for a flush finish, and often a damp or corrosive environment. These 4.2 x 25mm screws are built specifically for that job, fixing cement board to timber substrates and thin sheet metal up to 0.6mm thick.
The self-countersinking head has ribs underneath that cut cleanly into the board surface as the screw drives home, pulling flush without the need for pre-countersinking. It is a small detail that saves time across a full install.
What Makes These Cement Board Screws Different
The twin-cut point is designed for rapid pick-up and reduced torque through the drive. That means less effort per screw, less risk of cam-out, and a quicker fix overall. If you are running a full board installation, that adds up. The hi-low thread gives strong holding power in both timber and the board itself, keeping the fix tight and reducing any chance of pull-through over time.
Corrosion resistance is where these pull ahead of standard fasteners. The exterior-grade organic plating is rated to 1,500 hours in a salt spray test, making them a genuine option for facades, wet rooms, external sheathing and anywhere moisture or humidity is a regular presence. They also carry a Fire Classification of A1, which matters on projects where fire performance documentation is required.
Supplied in a box of 200, these are a practical trade quantity for a single room fit-out or as a working stock supply. At this price point, it makes sense to keep a box in the van.
Pro Tip: Run your drill at a controlled speed when fixing into cement board — too fast and the twin-cut point can skate before it bites, especially near edges where the board is most likely to fracture.
These screws are used across a wide range of cement board installations: wetroom and bathroom wall linings, external facade sheathing, soffit and cladding substrates, and underfloor backer boards where the fixing goes into a timber joist or batten below. They are the go-to choice wherever cement board meets a timber frame or thin metal track, and the exterior-grade coating makes them equally at home inside a shower enclosure or on the outside of a building.
Best For
Fixing cement board to timber
Fixing cement board to thin sheet metal up to 0.6mm
Wet rooms and bathrooms
External facade and sheathing boards
Underfloor backer board installations
Key Properties
Self-countersinking head with ribs
Twin-cut point for fast pick-up and reduced torque
Hi-low thread for strong holding power
Exterior-grade organic plating
1,500 hour salt spray rating
Fire Classification A1
Key Specifications
Size: 4.2 x 25mm
Max sheet metal thickness: 0.6mm
Box quantity: 200
Coating: Exterior-grade organic plating
Fire Classification: A1
Not suitable for: Not suitable for fixing into steel framing heavier than 0.6mm. Not designed for use with fibre cement slates or roofing applications where specialist fixings are required.
No pilot hole is required in the timber or sheet metal substrate. The twin-cut point self-drills on pick-up. Use a Pozi or Phillips bit at a moderate speed to keep control through the board surface. Drive until the head sits flush, the countersinking ribs will do the work without you needing to bear down.
Keep fixings at least 15mm from board edges to avoid cracking, and no more than 200mm apart across the field of the board. In wet area applications, ensure any exposed screw heads are sealed with a suitable waterproof compound before tiling or finishing.
Mark fixing positions at least 15mm from board edges and no more than 200mm apart across the board field
Set your drill or screwdriver to a moderate speed — no need for a pilot hole
Position the screw tip against the board face and start the drive at low speed until the twin-cut point bites
Increase speed to drive the screw through the cement board and into the timber or sheet metal below
Drive until the self-countersinking head sits flush with the board surface — the ribs will pull it level
In wet or external applications, seal any exposed screw heads before finishing
Can these screws be used on external cement board installations?
Yes. The exterior-grade organic plating is rated to 1,500 hours in a salt spray test, which gives genuine corrosion resistance in exposed or damp conditions. They are suitable for external sheathing, facade boards, and similar outdoor applications.
Do I need to pre-drill before using these cement board screws?
No. The twin-cut point is designed to self-drill on pick-up, so no pilot hole is needed in the timber or thin sheet metal substrate. Drive at a moderate speed and let the point do the work, especially near board edges where cracking is more likely.
These 4.2 x 25mm screws are manufactured with an exterior-grade organic plating that achieves a 1,500-hour salt spray rating, significantly outperforming standard zinc-plated fasteners in corrosive or damp environments. The hi-low thread design provides optimised pull-out resistance in both timber and cement board. Fire Classification A1 confirms the screws contribute no combustible material content, meeting requirements on fire-rated build-ups.
Size
4.2 x 25mm
Head Type
Self-countersinking with underhead ribs
Thread Type
Hi-low twin-cut
Coating
Exterior-grade organic plating
Salt Spray Rating
1,500 hours
Max Sheet Metal Thickness
0.6mm
Fire Classification
A1
Pack Quantity
200
Size
4.2 x 25mm
Reviews
There are no reviews yet.
Be the first to review “Cement Board Screws – Timber – Thin Sheet Metal – Box 200”Cancel Reply
Reviews
There are no reviews yet.