Unite thread forming type A
Thread Forming Type A Screws for Timber Fastening
What our thread forming type A screws are used for
Our thread forming type A screws are designed for pre-drilled fastening into timber. This family covers standard steel, flange-head, stainless and aluminium options, so the right choice depends on the timber detail, the project environment and the head or washer configuration you want on the finished installation.
Because this is a pre-drilled fastening family, the practical selection questions are different from self-drilling screws. The most important checks are material and corrosion fit, drill-hole diameter, available screw length and making sure that at least 30 mm of the screw fastens into the substrate.
What is included in our thread forming type A range
Standard carbon steel type A screws
Choose our standard carbon steel type A screws when you need pre-drilled fastening into timber and want the broadest spread of standard lengths for roofing, cladding or sheet-metal details. This is the core range when the project calls for a conventional steel solution rather than stainless, aluminium or a fixed-flange head style.
See sizes and details for our standard carbon steel type A screws on page 34 in the catalogue.
Flange-head type A screws
Use our flange-head type A screws when the installation is better served by a fixed 14 mm hexagon flange head instead of the standard washered layout. They follow the same pre-drilled timber fastening principle, but give you a clearly different head configuration for the detail you are building.
See flange-head sizes and details for our type A screws on page 34 in the catalogue.
Stainless type A screws
Choose our stainless A2 type A screws when corrosion resistance is a higher priority and you still want the same pre-drilled timber fastening principle. This part of the range includes both 4.8 mm and 6.5 mm screws, which makes it easier to match diameter and length to the application.
See sizes and technical details for our stainless type A screws on page 35 in the catalogue.
Aluminium type A screws
Use our aluminium type A screws when the material choice itself matters and you want to stay within the same type A system for pre-drilled timber fastening. This is a narrower subgroup than the steel range, but it solves a specific material-selection question quickly and cleanly.
See sizes and details for our aluminium type A screws on page 35 in the catalogue.
Detailed thread forming type A data in our catalogue
Below, you can review the article-level catalogue data for our thread forming type A screws. The most useful comparison points here are the split between carbon steel, flange-head, stainless and aluminium, together with screw diameter, length and the practical installation guidance for pre-drilled use.
These pages are also where it becomes easier to check the recommended drill-hole diameter and keep the selection tight to this family, without drifting into the adjacent light-section-steel thread-forming pages.
Need help choosing the right type A screw?
If you are choosing between standard steel, flange-head, stainless or aluminium type A screws, we can help you narrow the range quickly. We help professional buyers and installers match the fastening to the timber detail, corrosion demands and installation method before the order is placed.
How do I choose between carbon steel, stainless and aluminium thread forming type A screws?
Start with the project environment and the material logic around the detail. Carbon steel is the standard choice when that corrosion level is suitable, stainless A2 is the better fit when corrosion resistance matters more, and aluminium is the specialist option when the fastening material itself should suit an aluminium-based detail. The right choice is usually made before you compare length.
When should I choose the flange-head version instead of the standard type A screw?
Choose the flange-head version when you specifically want the fixed 14 mm hexagon flange head rather than the standard washered setup. The fastening principle into pre-drilled timber stays the same, but the head configuration changes the fit of the detail and can simplify selection when that head style is specified or preferred.
Do thread forming type A screws require pre-drilled holes?
Yes. This family is designed for pre-drilled holes, so hole preparation is part of correct installation. That makes hole diameter a real selection factor rather than an afterthought, and it is one reason this family should not be mixed up with self-drilling timber screws during specification or ordering.
How much of the screw should fasten into the timber?
For type A screws, at least 30 mm of the screw should fasten into the substrate. That rule matters because a visually suitable screw length is not always enough in practice; you need to account for the build-up you are fixing through and still leave adequate engagement in the timber.
What should I consider before choosing 4.8 mm or 6.5 mm type A screws?
Start with the detail, the available screw lengths and the drill-hole guidance for the chosen diameter. The range includes both 4.8 mm and 6.5 mm families, so the choice is not only about size in isolation; it also affects the matching hole diameter and which article lengths and materials are available for the application.
Can Unite help us choose the right type A screw for a project?
Yes. We can help you narrow the choice based on material, corrosion needs, head style, length and installation method before you buy. That is especially useful when several type A options look similar on paper but the wrong material or head configuration would slow the job down or create an awkward site detail.