To replace a staircase, measure rise and run, demo safely, then install new stringers, treads, risers, and rails to code.
Swapping a tired or unsafe stair for a new one isn’t just a looks upgrade. It’s a safety job with clear numbers you need to hit. This guide walks you through planning, demolition, layout, cutting, installation, and finishing. You’ll see the steps, the measurements that matter, and the tools that save time. You’ll also get a quick table of code numbers and a clean checklist so you can move with confidence from first cut to final rail.
Project Prep And Scope
Before you pry a single tread, map the full path. Confirm where the stair starts and lands, what walls or posts carry loads, and which finishes you’ll patch later. Decide if you’re keeping the layout or changing the rise/run, width, or landing. Lock a plan for materials, disposal, and a safe way for people to move between floors while the stair is out.
Stair Replacement Planning Checklist
Use this table to shape the job and spot risks early.
| Task | Why It Matters | Quick Check |
|---|---|---|
| Confirm Permits | Many areas require approval for stair work. | Call local building office; log permit number. |
| Measure Total Rise | Sets riser count and height. | Floor-to-floor including subfloors and finishes. |
| Measure Total Run | Drives tread depth and landing size. | String line or laser; note obstacles. |
| Check Headroom | Prevents code fails and bumped heads. | Map the 6′-8″ clearance arc above nosings. |
| Plan Temporary Access | Keeps people safe while stairs are out. | Set a ladder or outside entry with lighting. |
| Choose Stringer Type | Affects layout, cuts, and strength. | Cut notched 2×12s or use prefab steel/laminated. |
| Order Treads/Risers | Lead times can stall the job. | Hardwood, pine, or composite; match thickness. |
| Hardware & Adhesive | Quiet, tight steps last longer. | Construction adhesive, screws, structural fasteners. |
| Rail & Guard Plan | Graspable rail and guard height are code items. | Pick rail profile, brackets, post layout, baluster spacing. |
How To Replace A Staircase Safely: Step-By-Step
This section shows the full flow. Read it once, then stage tools and parts so you’re not hunting mid-build.
1) Document And Protect
Take wide and close photos of the existing stair, landings, and wall framing. Cover floors and set dust control. Kill power to any lights or outlets on stair walls if you’ll cut near them. Mark a safe path for people around the work zone.
2) Record The Numbers
Measure total rise from finished lower floor to finished upper floor. Divide by a riser target in the 7″–7-3/4″ range to find the riser count, then adjust to keep all risers equal. For treads, plan a depth of 10″ or more measured horizontally. Check width; 36″ clear is a common minimum. Map headroom along the nosing line. Note landing depth; 36″ is a common minimum where a landing is required. If you build in England, check “rise” and “going” limits under Part K.
3) Pull The Old Stair
Support adjacent framing if needed. Remove handrails and guards first. Work from the top down or the bottom up based on access. Cut fasteners that tie treads to stringers. Pry treads and risers with care so you can read how the old carpenter set the stringers. Free the stringers from ledgers, hangers, or posts. Keep the area blocked off once the stair is out.
4) Lay Out New Stringers
Use a framing square with stair gauges. Mark rise and run on a 2×12. Keep at least 3-1/2″ of meat at the narrowest point of each notch. Pull layout lines to the exact counts you solved earlier. Trim the bottom for plumb sit and the top for a clean seat at the header or landing. Dry-fit against the framed opening to confirm bearing, headroom, and landing alignment.
5) Cut And Test-Fit
Cut the first stringer and test it. Scribe minor tweaks rather than chasing small errors on every piece. Use the first stringer as a template for the others. Add riser and tread thickness to layout if you need closed stringers or housed treads. Seal end grain on exterior stairs.
6) Set Stringers And Bearing
Attach stringers to a ledger with approved hangers or to a header with structural screws. Shim only where allowed and only for plane, not for load. At the bottom, sit on solid bearing—landing framing, slab, or beam. Use corrosion-resistant hardware outdoors. Keep stringers plumb and parallel; check plane with a straightedge across the noses.
7) Install Risers And Treads
Glue and screw each joint. Keep riser heights equal within a tight 3/8″ window across the flight. Keep tread depth equal within the same window. Add nosings where needed and keep the projection consistent. Pre-drill hardwood treads to avoid splits. Use construction adhesive to quiet squeaks.
8) Add Handrails And Guards
Mount a graspable rail 34″–38″ above the nosing line. Set guards on open sides and landings; 36″ height is common in residences. Space balusters so a 4″ sphere can’t pass. Tie posts into framing with structural hardware, not just surface screws. Where one rail also serves as the guard top, keep the height in the same 34″–38″ window on the stair run. For the exact wording on tread, riser, and rail numbers in many U.S. jurisdictions, see the IRC stair section. If you build in England, check Approved Document K for “rise,” “going,” and guarding rules.
9) Finish, Sand, And Tune
Fill fastener holes. Ease sharp edges on treads and rail grips. Caulk riser joints if you want a painted look. Sand for stain or topcoat. Add skid-resistant finish on exterior steps. Walk the stair and note any squeaks or bounce, then tighten hardware or add blocks where needed.
Replacing A Staircase Cost, Tools, And Time
Costs shift based on materials, width, finishes, and any layout change. A straight interior stair with pine treads and paint runs far less than a hardwood showpiece with metal balusters. Exterior stairs add weatherproofing and corrosion-resistant hardware. Time also swings with demolition access, patching, and finish coats.
Core Tool List
- Framing square with stair gauges, tape, laser, and level
- Circular saw, miter saw, jigsaw, and oscillating tool
- Drill/driver, impact driver, and countersink bits
- Hammer, pry bars, and nail puller
- Construction adhesive and wood glue
- Structural screws, joist hangers, and post hardware
- Safety glasses, hearing protection, dust mask, and work gloves
Material Choices
Stringers: No. 2 or better 2×12 SPF, Douglas fir, LVL, or steel. Treads: hardwood (oak, maple), pine, or composite for decks. Risers: paint-grade poplar or plywood. Rails: graspable wood profiles or metal kits. Balusters: wood or metal; keep spacing tight for safety and code.
Time Planning
Set a two-day window for a basic interior straight run if framing stays the same and finishes are simple. Add time for landings, winder turns, metal rails, elaborate trim, or exterior coatings. Stage parts so you keep people moving between floors by day’s end.
Layout Math You’ll Use All Day
Rise And Riser Count
Divide total rise by a target riser height in the 7″–7-3/4″ range. Round to a whole number, then recalc the exact riser height so every riser matches. Keep the first and last risers within the same window; floor finishes often shift those two, so check them twice.
Run And Tread Depth
Pick a tread depth of 10″ or more measured horizontally. Add nosing if you need extra foot space on a thin tread. Keep the projection consistent across the flight. On closed stringers, subtract tread and riser thickness in your layout so finished sizes land on the marks.
Headroom And Landings
Hold at least 6′-8″ of clear height above the nosing line. Landings need depth at least equal to stair width in many cases; 36″ is a common number. Don’t crowd a door swing at the top of the stair; a door shouldn’t swing out over the steps.
Stair Code Numbers At A Glance (IRC)
Use this table as a quick reference while you work. Always confirm local adoption and any amendments.
| Item | Common Requirement | Source Pointer |
|---|---|---|
| Minimum Width | 36″ clear | IRC R311 (width) |
| Riser Height | Max 7-3/4″; uniform within 3/8″ | IRC R311.7.5 |
| Tread Depth | Min 10″; uniform within 3/8″ | IRC R311.7.5 |
| Nosing Projection | 3/4″–1-1/4″ (where nosing used) | IRC R311.7.5 |
| Headroom | Min 6′-8″ | IRC R311 (headroom) |
| Handrail Height | 34″–38″ above nosings | IRC R311.7.8 / R312 |
| Guard Height | 36″ at landings; 34″–38″ on stair runs | IRC R312.1.2 |
| Baluster Gap | < 4″ sphere | IRC guards (openings) |
Common Mistakes And Fast Fixes
Uneven First Or Last Riser
This often comes from missed floor finish thickness. Fix by adjusting tread or riser stock at those two locations. Aim to pull both back within the 3/8″ window.
Stringers Out Of Plane
If treads rock, your stringers aren’t in the same plane. Plane or shim to align, then glue and screw treads to stop squeaks.
Loose Or Squeaky Treads
Use adhesive along with screws. Add blocking under wide treads. For a finished stair, add screws from the underside or use trim-head screws through the riser and plug the holes.
Shaky Posts Or Guards
Surface screws into thin material won’t cut it. Set posts with through-bolts or hidden brackets that tie into joists or studs. Check guard height again after tightening.
Handrail That’s Hard To Grip
A flat 2×4 rail looks sturdy but isn’t a graspable profile. Pick a profile that fits the hand, and keep a 1-1/2″ clearance from the wall.
When A Layout Change Makes Sense
Sometimes a stair feels steep or cramped because the rise/run is tight. If your floor-to-floor is fixed, a landing split can ease the pitch. If you’re opening a wall, widening to 42″ improves traffic flow. Each change can affect headroom and landing size, so run the numbers before you frame.
Exterior Stair Notes
Use treated lumber or rated composites. Seal cuts. Pick hardware with the right corrosion rating for your climate. Add slip-resistant nosings or treads. Keep a clear path for drainage at landings. On decks, tie stringers into the framing with approved hangers and bolts, not nails alone.
Safety, Permits, And Final Inspection
Many building departments want a permit for stair replacement, especially if you change structure or layout. Schedule rough and final looks if required. Keep your layout math and material specs on site. Meet the inspector with clean, readable details: riser count, tread depth, rail height, and guard openings. If you follow the measurements in the code links above, the final walk-through goes smoothly.
Care After The Build
Wood moves. Screws relax. Walk your new stair after a week and again after a season. Tighten rail brackets. Re-caulk small seams. Touch up finish where shoes scuff the nosings. Small checks now keep the stair quiet and tight for years.
A Quick Word On Kits vs. Custom
Prefab stringers and rail kits speed things up, and many are rated for residential use. Custom work fits tricky openings, unusual widths, or special trim. If you pick a kit, match the rise and run to your exact floor-to-floor. If you go custom, take the time to template walls and landings so trim meets clean.
Ready To Start?
Print the tables, pull your measurements, and stage parts. If you keep equal risers, full tread depth, clean headroom, and solid rails, you’ll end with a safe, quiet stair that looks sharp. Use the exact phrase How to Replace a Staircase in your notes so you remember the full scope: planning, demo, layout, install, and finish. If a detail feels fuzzy, open the code links again, check the numbers, and adjust before you cut.
Recap Of The Flow
Plan the route and permits. Record total rise, run, width, and headroom. Remove the old stair in a controlled way. Lay out and cut stringers with a square and gauges. Set solid bearing. Glue and screw risers and treads with equal sizes across the flight. Install graspable rails and strong guards. Finish, sand, and tune. That’s the full arc of how to replace a staircase from first sketch to final wipe-down.