Nailer › First fix vs second fix nail guns
First fix vs second fix nail guns
First fix and second fix are stages of a building job, and each uses a different nail gun. Here is how to tell which you need.
What first fix and second fix mean
First fix is the rough, structural stage, done before plastering: stud walls, floor joists, roof timbers, noggins and battens. Second fix comes after plastering and covers the visible finishing: skirting, architrave, door linings, window boards and similar trim.
First fix nail guns
These are framing nailers. A UK hire firm says they are more powerful and can leave dents and chips, which is acceptable because the priority is getting the job done, not appearance. They are designed for clipped-head nails of 50 mm to 90 mm long. Another hire network says they drive larger nails for rough, hidden work such as roofing, wall framing and flooring. Typical features include a long strip magazine, a heavier body and a bigger driving force.
Second fix nail guns
These are finishing and brad nailers. They are lighter and more precise, using thinner nails with small heads, or none, which reduces splitting. According to the same hire firm they are designed for 16 gauge nails of 15 mm to 64 mm. They suit door frames, skirting and furniture. Because the nails are small, the holes are easy to fill and paint over.
Side by side
| First fix | Second fix | |
|---|---|---|
| Tool | Framing nailer | Finish or brad nailer |
| Work | Structure, hidden | Trim, visible |
| Nail length (typical, per one UK hire firm) | 50 mm to 90 mm | 15 mm to 64 mm |
| Nail head | Clipped or full round | Minimal or none |
| Marks on wood | May dent and chip | Small holes to fill |
| Power | Higher | Lower |
Which do you need?
- Building a shed, timber frame, decking or fence: first fix.
- Fitting skirting, architrave, door linings or cladding: second fix.
- Both in one project, such as a garden office: hire the one you use less. See hire or buy.
Fixing method and nails
Match the nail to the job: length should usually be at least two to three times the thickness of the material being fixed, so the nail goes deep into the second piece. Check structural requirements and building regulations if the work is load-bearing, as nail type and spacing may be specified. Look at nail sizes and gauges and collation angles to buy the right nails for your tool.
Planning a whole job
On a typical room extension or garden building, the first fix stage comes first and the second fix stage much later, sometimes weeks apart. If you are hiring, you may need two different tools at two different times, so book each separately rather than keeping one for the whole project. If you are buying, consider starting with the tool you will use most, then adding the other later.
Safety
First fix tools are strong enough to cause serious injury. HSE says to keep hands clear of the workpiece, avoid standing in the line of fire and keep fingers off the trigger when carrying: see safety.
See all tools in types of nail gun.
This is general information, not a substitute for the manufacturer's manual or training. Always check the nail sizes and collation your own tool accepts.
Frequently asked questions
Can I use a first fix nailer for skirting?
It is too powerful and leaves big marks. Use a second fix finish or brad nailer.
Can a second fix nailer frame a wall?
No. Its nails are too small for structural work.
What nail length does a first fix gun take?
One UK hire firm says 50 mm to 90 mm clipped-head nails. Check your tool.
What gauge do second fix nailers use?
One hire firm says 16 gauge, 15 mm to 64 mm. Brad nailers usually take thinner nails.