One of the most common questions we receive at Forxa is simply: how many spindles do I need? Get this wrong and you'll either have too few — leaving unsightly gaps — or too many, wasting money. This guide walks you through the calculation clearly and simply.

The UK Building Regulation Rule

Before calculating quantity, you need to know the rule. UK Building Regulations (Part K) state that spindles must be spaced so that a 100mm sphere cannot pass through any gap. In practice, this means the gap between spindles should be no more than 99mm.

This applies to any staircase where the drop is more than 600mm — which covers the vast majority of domestic staircases.

Step 1 — Measure Your Staircase

You need two measurements:

1. The horizontal run of your handrail — measure along the handrail from the bottom newel post to the top newel post in millimetres. Do not measure the stair treads — measure the handrail itself.
2. The width of each tread — if your staircase uses one spindle per tread, you'll need to count the number of treads instead.

Step 2 — Calculate the Number of Spindles

There are two common methods depending on your staircase type:

Method 1 — Handrail Length Method (most common)

Use this formula:

For example: if your handrail is 3,200mm long:

Always round up to the nearest whole number and we recommend ordering 5–10% extra to account for any cutting or damage during installation.

Method 2 — Two Spindles Per Tread

Many traditional staircases use two spindles per tread. Simply count the number of treads (steps) and multiply by two:

For example: 13 treads × 2 = 26 spindles

Quick Reference Table

Don't Forget the Landing

If your staircase has a landing with a balustrade (a horizontal section of railing), you'll need to calculate that separately using the same handrail length method. Measure each run independently and add the totals together.

Important — Check Before You Order

At Forxa, it is the buyer's responsibility to ensure the correct quantity is ordered before placing an order. We recommend:

• Measuring twice before ordering
• Adding at least 10% to your calculated quantity
• Confirming your spindle width — narrower spindles may need different spacing calculations
• Consulting a joiner if you are unsure

If you have questions about your specific staircase, email us at [email protected] and we will do our best to advise before you order.

When it comes to replacing or upgrading stair spindles, the first decision most homeowners face is the choice of material. Both metal and wood have genuine strengths — but they suit very different homes, budgets, and lifestyles. Here's everything you need to know.

Durability & Longevity

Metal Spindles

Metal spindles — particularly powder-coated iron — are exceptionally durable. They don't warp, crack, or split with changes in temperature or humidity. A quality powder-coat finish resists chipping, scratching, and everyday wear. With normal care, metal spindles will last decades without needing replacement.

Wood Spindles

Timber spindles are susceptible to swelling, shrinking, and warping over time — particularly in older homes with variable temperatures or damp. They can crack, split at joints, and are vulnerable to scuffs and marks. They typically require repainting or varnishing every few years to maintain their appearance.

Maintenance

Metal Spindles

Minimal. An occasional wipe with a damp cloth is all that's needed to keep powder-coated metal spindles looking their best. There's no painting, varnishing, or treating required.

Wood Spindles

Painted wood spindles need repainting every 3–5 years. Bare or varnished timber needs periodic treating. Any chips or cracks need filling and touching up. Over time the maintenance cost and effort adds up significantly.

Style & Aesthetics

Metal Spindles

Metal spindles offer an enormous range of styles — from clean contemporary flat bars and geometric forms to ornate traditional basket twists and decorative scrollwork. They suit modern open-plan homes as well as period properties. Available in 10 premium finishes including satin black, antique brass, gun metal grey and brushed nickel.

Wood Spindles

Wood spindles have a warmth and traditional character that metal can't fully replicate. They work beautifully in period cottages, farmhouses, and traditionally styled homes. However the range of profiles is more limited and they're less suited to contemporary interiors.

Cost

Metal Spindles

Metal spindles vary in price depending on the design and finish. Standard iron spindles are competitively priced, while luxury columns with crystal or gold accents command a premium. The key cost advantage is that you buy them once — there are no ongoing maintenance costs.

Wood Spindles

Basic turned wood spindles can be cheap to buy initially. However, when you factor in paint, varnish, and the time or cost of repainting every few years, the total lifetime cost is often higher than metal.

Installation

Both metal and wood spindles install in broadly similar ways — fixed to the handrail above and the base rail or tread below. Metal spindles are typically hollow or solid iron and may require specific shoes or bases depending on the fixing method. Your joiner will be familiar with both. Always ensure your installer checks the correct fixing method for the spindle type before ordering.

Summary

Choosing a spindle finish is about more than personal preference — it's about how your staircase will sit within the wider context of your home. The right finish ties together your flooring, handrail, door furniture, and interior style into a cohesive whole. Here's how to choose with confidence.

Start With Your Existing Hardware

The single most important rule: match or complement your existing door handles, light fittings, and taps. Mixing warm tones (brass, copper, bronze) with cool tones (silver, nickel, chrome) rarely works well. Identify whether your home runs warm or cool, then choose accordingly.

• Warm tones — brass handles, copper fittings, antique fixtures → choose ORC, ORB, WG or CV
• Cool tones — chrome handles, silver fittings, modern fixtures → choose STB, MB, GMG, SV or BN
• Neutral homes — white or minimal interiors → choose BW, MB or STB

All 10 Finishes Explained

Satin Black (STB)

The most popular finish by far. Satin black works in almost any interior — contemporary, industrial, transitional, and even traditional homes. It contrasts beautifully against light oak or white-painted stairs and pairs with any hardware colour. If in doubt, satin black is rarely wrong.

Matt Black (MB)

Similar to satin black but with a flatter, more muted finish. Suits interiors with a raw, industrial, or Scandi aesthetic. Works particularly well with exposed brick, concrete floors, or dark timber.

Gun Metal Grey (GMG)

A sophisticated mid-tone between black and silver. Ideal for contemporary interiors with grey tones — grey walls, slate floors, or grey-painted woodwork. A more subtle alternative to satin black.

Oil Rubbed Copper (ORC)

A warm, rich finish with depth and character. Suits transitional interiors — homes that blend traditional and contemporary. Beautiful against warm timber handrails and heritage-style interiors. Forxa's signature finish.

Oil Rubbed Bronze (ORB)

Darker and earthier than copper. Works brilliantly in period homes, Victorian terraces, and Arts & Crafts style interiors. Pairs perfectly with dark oak or walnut handrails.

Bright White (BW)

Clean, crisp, and classic. Ideal for white-painted staircases where you want the spindles to blend in rather than stand out. Works in Georgian and traditional homes as well as contemporary spaces.

White Golden (WG)

A warm off-white with a subtle golden undertone. Suits country, French provincial, and shabby chic interiors. A softer alternative to bright white.

Silver Vein (SV)

A textured silver finish with a subtle vein pattern. Works in contemporary and Art Deco inspired interiors. A more interesting alternative to plain chrome or silver.

Copper Vein (CV)

A textured copper finish with warmth and depth. Similar to ORC but with a more pronounced surface texture. Suits eclectic, bohemian, and industrial-influenced interiors.

Brushed Nickel (BN)

A cool, understated finish that pairs with modern chrome or brushed steel hardware. Suits contemporary and Scandinavian interiors. A more premium alternative to satin silver.

Match Your Handrail

Before ordering or installing stair spindles, it's important to understand the UK building regulations that apply. These rules exist to protect safety — particularly to prevent children from falling through or becoming trapped in balustrade gaps. Here's what you need to know.

The Key Regulation — Approved Document K

Stair spindles and balustrades in England and Wales are governed by Approved Document K (Protection from Falling, Collision and Impact). Scotland and Northern Ireland have their own equivalent standards which follow broadly similar principles.

Minimum Balustrade Height

The minimum height for a balustrade (measured vertically from the pitch line of the stair — i.e. the line connecting the front edges of the treads) is:

Note that these are minimum requirements. Many homeowners choose to go higher for aesthetic or safety reasons — particularly if young children are present in the home.

The 100mm Sphere Rule

This is the most important rule for spindle spacing. The gaps between spindles must be small enough that a 100mm diameter sphere cannot pass through. In practice this means the clear gap between spindles must be no more than 99mm.

This rule applies to all domestic staircases where the drop is more than 600mm and is specifically designed to prevent young children from getting their heads trapped in balustrade gaps.

Spindle Spacing in Practice

Your spindle spacing will depend on the width of the spindle itself. Use this as a guide:

Always verify this with your installer — the calculation must account for the actual finished gap, not just the nominal spindle width.

Structural Requirements

UK building regulations also specify that balustrades must be able to withstand certain loads. For domestic staircases, the balustrade must resist a horizontal force of 0.36 kN/m (kilonewtons per metre) applied at handrail height. In simple terms, it must be structurally robust — not just decorative.

The spindles themselves contribute to this structural requirement, which is why hollow spindles must be of adequate gauge and why the fixing method matters. Always use appropriate fixings and consult a qualified joiner for installation.

When Do You Need Building Regulations Approval?

Like-for-like replacement of existing spindles generally does not require Building Regulations approval. However you may need approval if:

• You are making structural changes to the staircase
• The property is a listed building
• You are converting a loft or adding a new staircase
• The work is part of a larger renovation requiring approval

If in doubt, contact your local building control department before starting work — it's a free call and avoids problems later.

Summary Checklist

• Balustrade height minimum 900mm from pitch line on stairs
• Balustrade height minimum 900mm from floor on landings
• Maximum gap between spindles: 99mm
• Balustrade must resist 0.36 kN/m horizontal load
• Use appropriate fixings and a qualified installer
• Check whether your project needs formal approval

About Forxa metal spindles

Forxa supplies fixed-length metal spindles that are cut to size on site and fitted into base and handrail brackets — the traditional, rock-solid retrofit method, and the system this guide covers.

What you'll need

• Tape measure and pencil
• Laser level (for marking spindles dead vertical)
• Power drill/driver and bit set
• Screwdriver bits
• Angle grinder with a metal-cutting disc
• Safety glasses and gloves
• Base and handrail brackets — available from forxa.co.uk

Step 1 — Remove the old spindles

Standard practice for a retrofit. Unscrew or carefully drill out the fixings holding each old spindle in place, top and bottom, then lift it out. If a spindle is glued or doweled in, you may need to cut it free with a multi-tool or small saw rather than forcing it. Once removed, fill and sand any old fixing holes in the baserail and handrail so you have a clean surface to work from.

Step 2 — Measure and plan your spacing

Measure the full length of the baserail and handrail, and divide by the number of spindles to work out even spacing. Mark each fixing point lightly in pencil before you commit to drilling.

Step 3 — Mark each fixing position with a laser level

For each pencil mark on the baserail, use a laser level to project a true vertical line up to the handrail and mark where it lands. This keeps every spindle perfectly upright and in line with its neighbours — even if your staircase isn't perfectly square (most aren't).

Step 4 — Drill pilot holes

Drill a pilot hole at each marked position on the baserail, and on the handrail if your bracket fixes there too. Match your drill bit size to the screws supplied with your brackets — too large and the fixing won't bite; too small and you risk splitting the wood.

Step 5 — Fit the brackets, cut and fit the spindles

5.1 — Fit and secure the base brackets

Position each base bracket over its pilot hole and drive in the fixing screws to secure it firmly to the baserail.

5.2 — Cut each spindle to length

Measure the gap between the base bracket and the underside of the handrail, and cut the spindle to length using an angle grinder fitted with a metal-cutting disc. Wear safety glasses and gloves, and deburr the cut end before fitting.

5.3 — Fit the spindle into the bracket and secure

Slot the cut spindle into the base bracket and tighten the grub screw (or fixing screw) to lock it in place. Repeat the same sequence — fit bracket, cut spindle, fit and secure — for each spindle along the run.

Step 6 — Step back and check

Once every spindle is fitted, walk the full run and check that:

• Every spindle is vertical and evenly spaced
• All fixings are tight, top and bottom
• Nothing rocks, rotates or rattles when you push it

Touch up any marks on the baserail or handrail left over from the old spindles, and you're done.