Part K Building Regulations Explained – Safety Glass, Falling & Impact

What is Part K?

Part K deals with protection from falling, collision and impact.

For window and door installers, it is particularly important for:

  • Safety glazing
  • Glass in doors
  • Low-level windows
  • Glazed screens
  • Full-height glazing
  • Guarding
  • Window openings
  • Restrictors

Safety Glazing

Glass in locations where somebody could reasonably collide with it needs to be appropriately safe.

Depending on the application, this commonly means:

  • Toughened safety glass
  • Laminated safety glass
  • Another compliant safety glazing product

The correct choice depends on location and performance requirements.

Doors

Glazing in and around doors is a classic critical location.

Think about:

  • Fully glazed doors
  • French doors
  • Entrance doors
  • Bifolds
  • Patio doors
  • Sidelights

Don’t assume a small pane doesn’t need safety consideration merely because it is narrow.

Low-Level Windows

Low-level glazing can present an impact risk because people may fall or walk into it.

The position of the glass relative to finished floor level is therefore important.

This should be checked at survey stage.

Finished Floor Level Matters

A common site mistake is measuring before final floor build-up is known.

Suppose the builder subsequently adds:

  • Insulation
  • Screed
  • Underfloor heating
  • Tiles

The finished floor level changes.

That can affect whether glazing falls within a critical safety location.

Always work from finished floor level, not simply the slab level during an early survey.

Toughened vs Laminated

Both can be safety glazing, but they behave differently.

Toughened glass is heat treated and designed to break into relatively small fragments.

Laminated glass incorporates an interlayer intended to retain fragments when broken.

Laminated glass can also be useful where additional requirements apply, including:

  • Security
  • Acoustic performance
  • Residual containment

We’ll cover this in dedicated toughened and laminated glass guides.

Falling From Windows

Part K isn’t just about somebody walking into glass.

Openable windows can also create a falling hazard.

This is particularly relevant with:

  • Low cills
  • Upper floors
  • Schools
  • Nurseries
  • Apartments
  • Full-height windows

Depending on the design, protection may involve:

  • Guarding
  • Restriction
  • Appropriate window design
  • Other measures

Restrictors

Don’t specify restrictors in isolation.

Ask:

  • Is this an escape window?
  • Is purge ventilation required?
  • Is Part O relying on the opening?
  • Is it a nursery or school?
  • What opening distance is required?
  • Does the restrictor need child-resistant release?
  • Is a particular tested standard specified?

A £10 hardware decision can affect several different regulatory requirements.

Manifestation

Large transparent glazed doors and screens can create a collision hazard because occupants may not realise glazing is present.

Manifestation or other visual indicators may therefore be needed in relevant locations.

This is particularly common in:

  • Offices
  • Schools
  • Shops
  • Commercial entrances
  • Large glazed screens

Part K and Part B

Sometimes a window needs both:

  • Protection against falling
  • Emergency escape capability

These requirements must be resolved together.

Don’t satisfy one regulation by accidentally defeating another.

Part K and Part O

Similarly, restricting a window to prevent falling can reduce the free opening available for summertime ventilation.

That can affect an overheating strategy.

Common Part K Mistakes

Using ordinary glass in a critical location.

Measuring from unfinished floor level.

Assuming toughened glass and laminated glass are interchangeable for every application.

Adding restrictors without checking escape requirements.

Ignoring manifestation on large transparent commercial glazing.

Treating safety glazing as a glass-only issue rather than considering the complete location and use of the building.

Real-World Example

A builder installs a large fixed pane next to an entrance door.

The bottom of the glass is close to finished floor level.

Because people can potentially collide with the glazing, the glass specification needs to account for its critical location.

The correct approach is to identify the requirement before ordering the sealed unit, not discover it during Building Control inspection.

Frequently Asked Questions

Is Part N still the current glazing regulation?

No. Relevant glazing safety guidance formerly in Approved Document N was incorporated into Approved Document K.

Do doors need toughened glass?

Glazing in critical locations needs appropriate safety performance. Toughened glass is one common solution, but laminated or another compliant safety glazing specification may be appropriate.

Does low-level glazing need safety glass?

Often yes where it falls within a critical location defined by the applicable guidance.

Can laminated glass be used instead of toughened?

Potentially, depending on the required classification and other performance requirements.

Can I fit restrictors to an escape window?

Potentially, but the complete arrangement needs to preserve the necessary escape function where required.

Related Guides

Link this article to Toughened Glass Regulations, Laminated Glass Guide, Escape Window Regulations, Window Restrictors, Part B, Part O and Building Control Checklist.

Trade Tech Technical Support

When requesting a quotation, tell us if glazing is:

  • Low level
  • In a door
  • Adjacent to a door
  • Full height
  • At an upper-floor level
  • In a school or nursery
  • Part of a guarding arrangement
  • Required to provide emergency escape

That allows the correct glass and hardware specification to be considered before manufacture.

Important: This is practical guidance for England. The actual project must be assessed against current Building Regulations, applicable standards, drawings and Building Control requirements.