If you’ve ever tried to creep across the landing, without disturbing the house, only to be betrayed by a loud creak, you’re not alone. Squeaky floorboards are a common nuisance, and the wrong screw sizes or types are causing the problem.

Choosing the right size and type of screws for floorboards is essential for preventing those unwanted creaks, letting you enjoy a stable, quiet floor.

Using screws that are too short or thin can lead to loose boards that shift with every step, while overly long screws risk damaging pipes or wires underneath. What’s more, the wrong type of screw can cause wood splitting or even failure to hold the board securely. This means you’ll experience persistent squeaks and potentially even structural issues over time.

In this guide, we’ll look at how choosing the right screws for various flooring types is important. We’ll discuss factors like screw length, diameter, and thread type, giving you the knowledge to make informed choices for your flooring projects.

Knowing the importance of proper screw selection helps you to avoid common pitfalls and enjoy a sturdy, silent floor.

Why screw size matters for floorboards

Structural integrity

Using the right screw size is essential to maintain the structural integrity of your floors, giving a stable connection between the floorboards and joists. Screws that are too short may not anchor the floorboards securely to the joists, which can result in movement and damage. Screws that are too long will go in too deep, which could impact underlying structures or utilities.

Noise reduction

Squeaky floors are usually caused by loose floorboards. When screws aren’t tightened enough or are too small, they can rub against each other or the subfloor, which leads to annoying noises.

Safety and durability

Loose floorboards can become trip hazards, and over time, the constant movement can cause wear and tear, ultimately leading to costly repairs.

Protecting joists and boards

Oversized screws can go in too deep, which may damage joists or even pierce through to the other side, which may impact your flooring. Undersized screws are unlikely to hold the floorboards securely, which can result in movement and damage to the boards and joists.

What size screws for floorboards? A quick table guide

Floorboard Type	Screw Length	Screw Gauge	Notes
Traditional Timber	50–65mm	#8 or #10	Pre-drill to prevent splitting
Chipboard (18mm)	40–50mm	#8	Use screws with coarse threads
Plywood Subfloor	50–60mm	#8 or #10	Pilot holes recommended
Engineered Wood Floors	45–60mm	#8	Consider underlay & allow for expansion

What size screws for 22mm floorboards?

For 22mm thick floorboards, you’ll want screws that are at least 2 to 2.5 times the thickness of the board, so:

Recommended screw length: 50-65mm
Screw gauge: #8 or #10
Thread type: Use full-thread or partially threaded screws depending on the material. Coarse thread is recommended for chipboard, while finer thread is recommended for hardwood.

What size screws for 18mm floorboards?

For 18mm floorboards, here’s a quick guide to choosing the right screws:

Screw length: 40-50mm
Screw gauge: #8 is ideal
Thread type: Use coarse-thread screws for fixing chipboard or softwood. If screwing into hardwood, use fine-thread screws.

Factors that affect screw size choice

1. Floorboard thickness

The thickness of your floorboards should be the first way to determine the right screw length. Use a tape measure to get the exact size.

A common guideline is to use screws that are 2.5 times the thickness of the floorboard. So, if you have 18mm floorboards, you’ll use a 45mm screw length. This helps to get the right amount of penetration into the joist to secure the hold.

2. Joist material and spacing

The material and spacing of your joints can have an impact on the screw size you need. Softwood joists, like pine, are more forgiving, and screws go into them easily. Hardwood joists, like oak, are denser, and you’re going to need to pre-drill holes to prevent the wood from splitting. In the UK, floor joists are commonly spaced at 400mm or 600mm centres. The wider the space, longer screws may be needed to get a good anchor to the floorboards.

3. Room type and load considerations

The function of the room and furniture in the room can also impact your screw size choice. In rooms where there is heavy foot traffic, you’ll need longer and sturdier screws to deal with the constant movement.

In rooms where heavy items are, screws that give a stronger hold are best to help reduce the chance of floorboard movement or squeaking over time.

Lofts aren’t typically used as much as the ground floors in your home. However, if you convert it into living space, you’ll have to consider the load in there, and adjusting the screw size might be best to give you stability.

Recommended screw types for floorboards

Wood screws (Standard)

Best for: Softwood and traditional timber boards

Standard wood screws are a reliable choice for securing softwood and traditional timber floorboards. With a sharp point and coarse threads, they go into the wood easily and have a strong hold.

Flooring screws

Specially designed for floorboards

Flooring screws, such as tongue and groove screws, have been specially engineered for floorboard installations. They’re mostly designed with self-drilling tips and countersinking heads, which means there’s no need to pre-drill, and you get a flush finish.

Twinthread vs Single thread

Advantages for gripping subfloors and preventing movement

Twinthread screws: These screws have two threads that run along the shank, which gives you a quicker insertion and strong hold. They’re ideal for use on hardwood, softwood and jobs where you need robust fastening.

Single-thread screws: This has a single continuous thread, which gives them good drip in softwoods. They’re ideally used where strong pull-out resistance is needed.

Self-drilling vs pilot holes

Self-drilling screws: These screws come with a drill-like top, that means they cut their own pilot hole as they’re driven in. They are best used in softwoods and other materials where pre-drilling isn’t needed.

Pilot holes: For hardwoods and brittle materials. It’s best to pre-drill pilot holes to prevent splitting and to get the most accurate placement.

Should you nail or screw floorboards?

The classic debate: nails or screws? If you’re laying floorboards and wondering which method will give you the best results, let’s break it down.

Nails vs Screws: What’s the Difference?

Feature	Nails	Screws
Holding Power	Moderate (can loosen over time)	Strong, resists movement and squeaks
Ease of Installation	Faster with a nail gun or a hammer	Slower but more precise
Removability	Harder to remove without damage	Easy to back out if needed
Movement Resistance	Less secure—boards may shift or creak	Excellent for keeping boards tight

Why screws are a smarter choice for most floorboards

If you want long-term peace and quiet from your floor, then screws are the better options:

They hold tight: Screws will grip the joists firmly and are less likely to loosen over time.
They stop squeaks: Since they reduce movement, screws are the better choice to prevent creaky spots in your home.
They’re easy to adjust: If you’ve put them in slightly off, it’s much easier to unscrew and reposition them.

When nails still make sense

That said, nails aren’t obsolete just yet. There are still a few times that they’re the better choice:

Restoration work: Matching the fixing method used in period properties may require traditional nails, especially when aesthetics are a priority.
Secret nailing: For tongue-and-groove boards, nails can be driven at an angle through the tongue and hidden, giving you a neat finish.
Speed: If time is time and you’re using a nail gun, you’ll get the job done quickly.

Tips for installing floorboards with screws

Getting the right screws is only half the battle, how you install them matters too. Here are some tips for installing floorboards with screws.

Pre-drilling: Small step, big payoff

Driving screws straight into hardwood can cause boards to split, especially if you do it near the edges or ends.

When pre-drilling, use a drill bit that’s just slightly smaller than your screw’s core to create the pilot holes. This helps to guide the screw, reduces splitting, and makes for a cleaner job, especially when you’re working with dense woods like oak and beech.

Countersinking: For a flush finish

Catching your foot on a raised screwhead is not ideal. If you use a countersink bit, you’ll create a slight recess in the board, which lets the screwhead sit just below the surface. You can then fill this and get a clean-looking finish.

Glue and screw?

Screws give you an excellent grip for floorboards, but sometimes a high-quality flooring adhesive (like MS polymer or PU-based glue) will give you an added extra bond strength. This can be useful in high-traffic areas of the home.

Remember to use the glue sparingly; a little goes a long way. Plus, you’ll need to allow for slight seasonal movement.

Spacing and pattern

A few key rules to follow:

Screws every 200-300mm along the length of the board
Minimum 15mm from edges to avoid split
Always screw into joists, not just the subfloor
For narrow boards, 1 screw per joist is fine.
For wider boards, go for 2 screws spaced evenly across the width
Alternate your screw position slightly on each board to reduce the chance of cracking joists in the same line

Common mistakes to avoid

Small missteps can lead to costly and time-consuming problems when you’re installing floorboards. Avoid these common mistakes to get the job right the first time.

Using the wrong size screws

We’ve given you the guide; now use it. If not:

Too short? Your boards will lift and squeak because they aren’t gripping the joist beneath them.

Too long? You could pierce through the joist and hit things like pipes or wires.

Over-tightening and splitting the boards

Cranking that screws it until it squeals might feel satisfying, but it’s likely to lead to cracked timber. If you do this, screws might pull too hard on the fibres of the wood. Stop tightening once the screw head is just below the surface.

Misaligned joists mean wobbly boards

Don’t just guess where the joists are, if you miss them, you won’t be adding strength to the floorboards and over time, they’ll shift or lift. It’s best to use a joist finder or lift a small section to mark joists properly before you start.

Ignoring wood movement

Wood moves. It breathes with the seasons, expanding in humid months and shrinking in dry ones. If you install your boards too tightly with no gap between the boards or walls, you might get buckling, squeaking or gaps.

It’s best to leave a 2-3mm expansion gap between the boards and at least 10mm from walls. Spacers will help you here; remember to remove them when done.

Done right, floorboards stay quiet for years

Choosing the right size and type of screw isn’t just a nice-to-have; it’s the difference between a floor that stays solid and silent, and one that groans with every step.

Whether you’re working with softwood, hardwood, or tongue-and-groove, there’s a screw that’s made for the job.

Enter ASP Ltd, we’ve got a wide range of flooring screws that are available in the sizes you actually need. We stock solid, reliable screws you can count on to keep your floorboards where they should be – quiet and firm.