When is safety glass required in doors?

Under Approved Document N (now K) of UK Building Regulations, safety glass must be used in any glazed panel in a door and in any glazed area within 300mm of a door edge up to 1500mm from floor level. Door glazing below 800mm from the floor is always in a critical location. Safety glass means toughened to BS EN 12150 or laminated to BS EN 14449, both must pass the impact test in BS 6206 Class C or EN 12600.

What is the difference between toughened and laminated glass in doors?

Toughened glass is 4-5 times stronger than annealed glass and breaks into small, relatively harmless fragments. Laminated glass has a PVB interlayer that holds fragments together when broken, providing better security and sound insulation. For front doors, laminated is preferred for security. For internal doors, toughened is common due to lower cost. BS 6262-4 gives guidance on glass selection.

How do I measure glass for a door panel?

Measure the aperture (rebate to rebate) and deduct the beading overlap on each side, typically 8-12mm per side. For a 500mm aperture with 10mm beading overlap, the glass size would be 480mm. Always measure at three points and use the smallest dimension. Allow 2-3mm clearance for thermal expansion in dark-coloured doors.

What glass thickness do I need for door panels?

For small panels (under 0.5m2), 4mm toughened is adequate. Medium panels (0.5-1.5m2) need 6mm toughened or 6.4mm laminated. Large panels (1.5-2.5m2) require 8mm toughened or 8.8mm laminated. Full-height glass doors typically use 10mm toughened or 11.5mm laminated. These are minimums; always check with your glass supplier for specific loadings.

Can I use decorative glass in a door?

Yes, but it must still be safety glass in critical locations. Decorative obscure glass is available in toughened form to comply with BS 6206. Popular patterns include Cotswold, Flemish, Autumn, and Contora. For composite doors, decorative cassettes with internal Georgian bars and obscure outer pane are common. Ensure any decorative glass meets the relevant safety standard for its location.

TradeCalculator.co.uk

Door Glazing Calculator

Calculate glass panel sizes, safety glass requirements and Part N zones for doors

Door type

Door width (mm)

Door height (mm)

Glass panel width (mm)

Glass panel height (mm)

Panel bottom from floor (mm)

Glass type

Glazing unit

Number of doors

How We Calculate This

This calculator sizes glass panels for door glazing by deducting beading overlap from the aperture dimensions. It checks whether the panel falls within a Part N (Approved Document K) critical location based on height from floor level, and recommends minimum glass thickness according to panel area and maximum dimension per BS 6206 and EN 12600 guidelines. Georgian bar counts are derived from glass dimensions divided by bar pitch.