How to Build Stairs — Step-by-Step UK Guide

What You'll Need

Before You Start

• Measure the total rise carefully — from finished floor to finished floor above. This is the most critical measurement. Get it wrong and nothing else works.
• Contact Building Control before starting. You will need to submit a Building Regulations application.
• Use our Staircase Calculator to calculate the number of steps, rise, going and stringer dimensions, and our Spindle Spacing Calculator for balustrade spindles.
• Check the headroom — minimum 2000mm measured vertically from the pitch line at any point. If headroom is tight, you may need to adjust the stair position or trim the floor opening.
• This is an advanced carpentry project. If you are not confident, consult a carpenter or consider ordering a pre-made staircase to your measurements.

Step-by-Step Instructions

Step 1: Calculate Rise and Going

Measure the total rise (finished floor to finished floor). Divide by your target individual rise (e.g., 200mm). Round to a whole number of steps. Recalculate the exact individual rise: total rise divided by number of steps. Calculate the going using the formula: 2R + G = 600mm (ideal). For example, with 200mm rise: going = 600 - (2 x 200) = 200mm. Check this falls within the 220-300mm going requirement — if not, adjust the number of steps.

Step 2: Mark Out the Stringers

Set up stair gauges on a framing square at your rise and going dimensions. Starting from the bottom of the stringer board, mark each step — the rise on one edge, the going on the other. You will have one fewer going than rises (the floor at the top acts as the final going). Mark the top and bottom cuts to account for the tread thickness and floor level.

Step 3: Cut the Stringers

For cut (open) stringers, cut along the marked lines using a circular saw for the straight cuts and finish the corners with a handsaw (do not overcut with the circular saw). For closed (housed) stringers, route trenches 12mm deep into the stringer to receive the treads and risers — use a router with a template.

Step 4: Install the Stringers

Fix the wall stringer to the wall using frame fixings into the masonry or studs at every other step. Fix the outer stringer temporarily in position. Check that the treads will be level across both stringers at every step. Fix the bottom to the floor and the top to the landing trimmer joist using joist hangers or bolts.

Step 5: Fit the Risers

Starting from the bottom, fit each riser into the stringer housings (or against the cut stringer). Glue and screw from the back. For housed stringers, tap hardwood wedges coated with PVA into the housing gaps to lock the risers in place.

Step 6: Fit the Treads

Fit each tread from the bottom up. The front edge of the tread should overhang the riser below by 16-25mm (the nosing). Glue and screw through the tread into the top of the riser below. Add glue blocks in the angle between the tread and riser underneath for extra rigidity. Tap wedges into the stringer housings.

Step 7: Install Newel Posts

Fix the bottom newel post to the floor using a M12 draw bolt through the floor joist, or bolt to the side of the stringer. Fix the top newel to the landing trimmer joist. Newel posts must be rigid — they take significant force from the handrail and balustrade.

Step 8: Fit Handrail and Spindles

Fix the handrail between the newel posts. The handrail height must be 900-1000mm measured vertically from the pitch line (the line connecting the nosings). Fix spindles into the treads and handrail — two per tread is typical. Ensure no gap larger than 100mm exists between spindles.

Step 9: Finish

Sand all surfaces. Fill any gaps with wood filler. Prime and paint, or apply oil/varnish for a natural timber finish. Fit a scotia or cover mould where the stringer meets the wall.

Common Mistakes to Avoid

• Wrong total rise measurement: Even 5mm error per step multiplied by 13 steps is 65mm total — enough to fail inspection. Measure three times.
• Ignoring Part K: Building Control will inspect. Non-compliant stairs must be rebuilt. Know the regulations before you start.
• Inconsistent rises: All rises must be equal (within 2mm tolerance). Variable rises cause trips — this is a safety issue, not just aesthetic.
• Weak newel post fixing: A wobbly newel makes the whole balustrade unsafe. Use proper draw bolts or coach bolts, not just screws.
• Forgetting the nosing in calculations: The tread nosing overhangs the riser but does not count as part of the going. The going is measured from nosing to nosing.

Cost Estimate (2026 UK Prices)

Use our Staircase Calculator and Spindle Spacing Calculator for precise dimensions and material quantities.