Trades master copy
Last reviewed: March 2026
What Part K is
Part K is the safety-at-height part of Building Regulations. For dwellings it covers stairs, ladders, ramps, guarding (balustrades/handrails), and where you need safety glazing or guarding to stop people falling or walking into things.
The aim is: people can move between levels without falling, and they don't get badly hurt by low sills, big drops, unguarded landings or vulnerable glazing.
This guide is a summary to make Part K easier to use on site. It does NOT replace Approved Document K: Protection from falling, collision and impact (current edition, which also now covers glazing that used to be in Part N).
You must read and follow the full Approved Document K and any stair/guarding/glazing manufacturer data for your project.
This guide is written for England. Wales, Scotland and Northern Ireland have their own versions of building regulations - the principles are similar but the documents and approval routes differ, so check local requirements if you're working outside England.
Where it applies on your jobs
For small builders and fit-out trades, Part K hits all the usual suspects:
- New stairs and stair alterations - in new builds, loft conversions, refurbs and extensions.
- Landings, galleries, internal balconies and split-levels - anywhere with a drop over about 600 mm in dwellings.
- Ramps and external steps around entrances, patios and garden access.
- Guarding to edges - stairs, landings, flat roofs where people have access, lightwells, basement areas.
- Glazing in "critical locations" - glass in and around doors, low-level windows, large internal screens.
Part K sits alongside Part B (fire), Part M (access) and the old Part N glazing rules (now pulled into K). The same stair or balustrade often has to satisfy all three: safe to use, accessible, and adequate for fire escape.
Key "trigger points" - what bites on site
Stair design and alterations
Domestic stairs have basic rules for rise, going, pitch, width, headroom and landings - blow those and Building Control will push back.
Typical domestic stair rules (check current AD K for exact numbers):
- Max pitch around 42°.
- Consistent rise/going within a flight.
- Clear headroom usually at least 2.0 m on the pitch line.
- Landings at top/bottom and where stairs change direction.
Loft conversions are notorious for compromised headroom and tight winders - you need to design it properly, not fudge it on site.
Guarding to stairs, landings and edges
In dwellings, guarding is normally required where there's a drop of more than 600 mm internally or at accessible external edges.
Guarding must:
- Be high enough (domestic stairs/landings typically around 900-1100 mm above pitch line/floor).
- Be strong enough to resist people leaning/falling on it.
- Prevent children from climbing through - usually no gaps bigger than 100 mm.
Ramps and level changes
- Ramps need safe gradients, landings and guarding if the drop exceeds the threshold.
- Short "cheeky ramps" and odd two-step arrangements at entrances are a common fail - you still need to meet both Part K (safety) and Part M (access).
Glazing in critical locations (old Part N now in K)
- Glazing in doors and side panels below 1500 mm from floor level, and windows below 800 mm from floor level in areas where people walk, is typically treated as a "critical location".
- In these locations, glass must either:
- Be a suitable safety glass (toughened or laminated), OR
- Be protected by guarding/screening so people can't hit it.
- Large clear screens and balustrades need both safety glass and, often, visibility markings to stop people walking into them.
Quick reference table - common jobs
New stair for loft conversion
- Overall pitch, rise and going must meet domestic stair rules; no silly steep ladders passed off as stairs.
- Maintain at least 2.0 m headroom where possible; any relaxation needs agreeing with Building Control and often affects Part B fire strategy.
- Provide handrails and guarding to open sides, with no gaps over 100 mm.
Opening up stairwell with feature balustrade
- Guarding height at landings and along the stair must meet AD K; wire/vertical bar designs must keep gaps under 100 mm.
- Balustrade must resist load - flimsy glass clips or undersized fixings are a fail.
- If you use glass balustrades, glass must be safety glass to the right standard and sized correctly.
New full-height glazing next to a door to garden
- Door and side panel glazing down to floor level are in a critical location - must use safety glass (toughened/laminated) or shielding.
- Consider visibility markings at eye level so people don't walk into it.
- Any low sill next to a drop may also need guarding or height adjustments.
Patio with drop to garden more than 600 mm
- Provide guarding to the edge where people can access - height and gaps as per domestic guarding rules.
- If you're also doing ramps or steps, make sure they're safe for use (treads, risers, nosings, handrails) and tie into Part M access requirements.
New internal gallery/mezzanine
- Robust guarding to the perimeter, height and gaps to AD K.
- Guarding must resist horizontal load - often needs designed fixings and posts, not just "nice-looking" timber slats.
- If glazing is used, treat it as balustrade glass, not just a window.
Routes to compliance for trades
Use Approved Document K as your default pattern
Follow the AD K tables/diagrams for domestic stairs (rise, going, pitch, headroom), landings and guarding heights.
Follow the critical-location diagrams for glazing, and default to safety glass or guarding where in doubt.
Coordinate with Parts B and M
Any stair or ramp has to satisfy Part B (fire escape), Part M (access) and Part K (safety).
Don't tweak stairs or landings on site for "looks" or "space" without checking all three.
Treat bespoke balustrades and big glass as engineered items
Glass balustrades, slim steel rails and large internal screens often need an engineer/manufacturer to design the system and fixings to meet loading requirements.
Don't swap components (glass thickness, posts, fixings) without checking you're still compliant.
For glazing, if in doubt, use safety glass
It's rarely worth arguing borderline "critical location" cases on small jobs - toughened or laminated safety glass in potentially exposed areas is often the simple answer.
Just make sure you use the right spec (toughened, laminated, or both) for the location and size.
Who is responsible for what
On a typical domestic project:
- The designer/architect is responsible for stair layouts, guarding, ramp gradients and specifying where safety glazing is required.
- The builder/main contractor is responsible for actually building stairs, landings and guarding to those dimensions and specs - not shaving widths, headroom or balustrade height to suit finishes.
- The joiner/metalworker/glazier is responsible for fitting balustrades and glazing to the tested system details, with correct glass type and fixings.
- The client/owner lives with the safety risk and Building Control consequences if it's wrong.
Blunt version:
If you decide on site to steepen a stair, lower a balustrade, or use standard float glass where Part K expects safety glass, that's on you. When someone trips, a kid falls through the spindles, or a surveyor flags unsafe glazing, you're back there fixing it - or worse.
Simple rule to drum into your team
If you're building or changing stairs, edges, or any large/low glass, treat it as a Part K job. Check heights, gaps and glass spec against the diagrams before you sign it off.
On-site checklist (Part K)
Before you start
- Confirm stair layout, dimensions and headroom from the drawings - rise, going, pitch, landings.
- Identify all edges with drops over 600 mm and any proposed glass in/near doors or at low level.
- Check what type and thickness of glass/balustrade system is specified for each location.
While you're working
- Build stairs exactly to the agreed dimensions - don't "lose a bit" in the going or headroom because it's tight.
- Install guarding/balustrades to the correct height with no gaps over 100 mm; fix posts and rails robustly to structure, not just plasterboard.
- Make sure any glass in doors, side panels, low-level windows or balustrades is the specified safety glass and protected until handover.
When you finish
- Measure stair rise/going, headroom and guarding height with a tape - don't eyeball it.
- Check all drops over 600 mm where people have access are guarded, inside and out.
- Confirm any critical glazing has the right marking/ID and, where needed, visibility markings for large panes.
Sources
Based on:
- Approved Document K: Protection from falling, collision and impact (current edition, including rationalisation with former Part N glazing requirements).
- Planning Portal, LABC and industry summaries of Part K for domestic stairs, guarding and safety glazing.
- Specialist guidance on safety glazing in critical locations and balustrade glass (requirements for toughened/laminated glass and critical zones).
This guide was last reviewed March 2026. SiteKiln does not provide legal, financial or tax advice. All content is for general information purposes only. Always seek professional advice for your specific situation.
Know someone who needs this?
Working in Wales? The building rules are different. See our Working in Wales guides.
Working in Scotland? Building standards work differently. See our Working in Scotland guides.
Working in Northern Ireland? The system uses Technical Booklets. See our Working in Northern Ireland guides.
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