Cricklewood Glass - Quality Products & Services Since 1986

Now At Larger Premises: Unit 6d, Atlas Business Centre, Oxgate Lane, London, NW2 7HJ

Glass - Glazing - Secondary Glazing - Soundproof Windows - Splashbacks & Worktops -  Double Glazing & Units - Mirrors - Table Tops - In fact, Everything Glass!

Aluminium Secondary Glazing - Specifications, Uses & Applications, Drawings & Downloads

Combination of Lift Out and Vertical Sliders in a Victorian Sash Bay Window Secondary Glazing London

Secondary Glazing Product Range

We have a comprehensive range of secondary glazing units to suit every use and application.

For a quick visual look at products, dimensions and configurations, please see:

Standard Aluminium Secondary Glazing

  • Horizontally Sliding Secondary Glazing
  • Vertically Sliding Secondary Glazing Units
  • Hinged Secondary Glazing, Top, Side & Double
  • Lift Out Secondary Glazing
  • Fixed Secondary Glazing Panels


  • Casement and Double Sash Windows
  • Sash Windows
  • Casement Windows & Doors
  • Casement & Small Sash Windows
  • Part Glazed Doors & Fixed Casements

Our standard secondary glazing frame finish is White, we also stock Brown and Silver Anodised finishes and can paint finish to any RAL colour to match or complement your windows & decoration.

Secondary Glazing Supplies - Common Product Specifications

High Quality Warp Free White Gloss Finish Aluminium Frame Sections Secondary Glazing London

London secondary glazing products are available in a wide variety of styles along with accessories and options.

The standard specifications, however, are common throughout the product range, as detailed below:

Aluminium Extrusions

All sections are extruded to exclusive designs and manufactured from aluminium alloy 6063T6 and produced in accordance with the BS EN 755 standard - to be rigid and free of warping.

Aluminium Finishes

The standard finish for all secondary glazing panels and frames is a 60-micron polyester powder coated White High Gloss Finish, produced in accordance with BS 6496.

Manufacturing Fixings

ABC Spax Hi

Dependent upon the type of secondary glazing frames - mechanically crimped concealed solid aluminium corner cleats - or - stainless steel and bright zinc plated screws.


Standard Glass is 4 mm Clear Float, Secondary Glazing London

With the exception of - Tilt-In versions of Vertically Sliding Secondary Glazing for Sash Windows - all secondary glazing panels come as standard with 4mm thick clear float glass, however please refer to the Glass Safety Note below.

Tilt-In versions of the Vertical Sliders - come as standard with 4mm thick toughened clear float safety glass.

Glass Safety Note

All Glass must be specified, manufactured and supplied in strict accordance with BS 6262, BS 6206 and Section N1 of Approved Document N of the Building Regulations - which between them specify the Safety Glazing requirements for all areas of “Special Risk,” including “Bathing and Washing Areas.”

Gaskets & Glazing

Standard Black Glazing Gaskets, Secondary Glazing London

Secondary glazing panel and sealing gaskets are all extruded from synthetic rubber in accordance with ISO 14309:2011 - Rubber, vulcanized or thermoplastic - Determination of volume and/or surface resistivity.

This ensures that they do not “shrink” over time and that they retain the “memory” of their original manufactured shape, allowing them to be compressed then spring back to shape thousands of times as units are opened and closed.

The standard colour is black.

All glazing and gaskets are designed and assembled in order to facilitate easy demounting for glass replacement in the event of a breakage.

Draught Seals

Polypropylene Brush Seals, Secondary Glazing London

Dependent upon the type of secondary glazing product:

  • All sliding secondary glazing, framed hinged secondary glazing and lift out secondary glazing use polypropylene brush seals manufactured in accordance with BS 7386
  • Non-framed hinged secondary glazing and fixed secondary glazing panels use compression seals manufactured in accordance with BS 7412 & BS 5750

The standard draft seal colour is light grey.

Sub Frames

Sub frames are manufactured to KD:FAS1F for stability and painted with two coats of acrylic white primer ready for final finishing.

KD signifies Kiln Dried and ensures that timbers will remain warp and twist free. FAS signifies Firsts and Seconds which are high grade joinery timbers, guaranteed to be free of defects such as knots and worm holes.

Round Secondary Glazing Units for Porthole Windows, London Secondary Glazing

Special & Bespoke Secondary Glazing Products

  • Curves in the Face Elevation
  • Curves in the Plan Elevation
  • Semi-Circular
  • Circular
  • Elizabethan Arched Heads
  • Gothic Arched Heads
  • Triangular & Trapezoid
  • High security specification
  • Out of Square
  • Secondary Glazing Fly Screens
  • Incorporating Trickle Vents
  • Any RAL Colour Finish
  • Specialist Glasses
  • Specialist Film Applications
  • Fire Rated
  • Glazing with ultraviolet filter

Secondary Glazing Supplies - Special & Bespoke Products & Specifications

Secondary Glazing Fly Screens

Hinged Secondary Glazing with Fly Screen Mesh Secondary Glazing London


Additionally, many of the secondary windows can be supplied with interchangeable inserts - with fly-screens for summer pest & insect control - and secondary glazed for winter thermal insulation.

The fibre glass fly-screen mesh is translucent, providing excellent visibility and ventilation, as well as being both corrosion and combustion resistant.

Woven from fibre glass yarn, the mesh has a protective vinyl coating that is resistant to staining and easy to clean.

The standard fly screen mesh colour is a very light grey and once fitted it is virtually invisible.

Standard gauge is 18 x 16 - 18 threads in one direction and 16 in the other - per square inch.

Secondary Glazed Fly Screens - Commercial

The Food Safety (Food Hygiene) General Regulations 1995 state that windows which are opened to the outside environment must, where necessary, be fitted with insect proof mesh.

The use of secondary glazing units with fly-screen in a commercial environment such as a kitchen, café, restaurant, bakery, food retailer or food processing factory, ensures compliance with the hygiene regulations.

They prevent the entry of disease carrying flying insects and thus reduce the reliance upon chemicals and sprays.

Secondary Glazing with Fly Screen Mesh Complies with Food Safety Hygiene General Regulations Secondary Glazing London


  • for the exclusion of all flying and crawling insects

Guidance & Restrictions

Some larger secondary glazing units may require the addition of discreet “H” bars to provide additional rigidity to the panels and ensure correct operation of the secondary glazing.

Secondary Glazing Fly Screens - Product Range

Manufacturing - Standards

  • translucent light grey woven fibre glass 18 x 16 gauge mesh

Manufacturing - Options

  • 30 x 20 gauge fine mesh
  • extra fine Polltec © mesh for hay fever sufferers
Horizontal Slider with Fly Screen, Colour Matched Frame and Vertical Cavity Blind, Secondary Glazing London

Available for the following Secondary Glazing Types

  • fixed panels
  • hinged units
  • lift outs
  • horizontally sliding
  • vertical sliders - standard non-balanced units only
  • door units
  • double (French) door units

Secondary Glazing Fire Resistant Units


Fire resistant secondary glazing units are available either as Hinged or Fixed Units only and are manufactured with steel frames.

As well as side and top hung hinged secondary windows, double hung units are available for double casement windows, French and Sliding/Patio Doors.

Fire resistant windows can be created by upgrading rather than replacing the existing windows - by installing secondary steel windows with fire retardant glass that have been 30, 60 or 120 minute fire tested in accordance with BS476: Parts 20/22.

Steel Framed Pyro Glazed Units comply with BS476 Parts 20 to 22 Secondary Glazing London


Fire Resistance

Maximum Sizes, Guidance & Restrictions

Secondary Glazing - Hinged Units

Side Hung

  • 1200 mm width x 1800 mm height

Top Hung

  • 1800 mm width x 1200 mm height

Double Hung

  • 2400 mm width x 1800 mm height
Steel Secondary Window undergoing Fire Testing in accordance with BS476 Secondary Glazing London

Secondary Glazing - Fixed Units

  • 1400 mm width x 2000 mm height

Secondary Glazing - Steel - Manufacturing Standards

  • Fire Resistant units from 30 up to 120 Minutes Integrity to BS476 Parts 20 to 22
  • steel window frames
  • steel hinges
  • fire retardant gaskets or fire retardant glazing tape with intumescent sealant
  • 6mm clear Pyran or Pyroswiss glass
  • steel glazing beads
  • stainless steel lever handles
  • 2 point latch deadlock
  • manually locking twin rod flush bolts to slave doors
30 60 and 120 Minute Fire Retardant Glass, Secondary Glazing London

Manufacturing - Options

  • any RAL colour finish
  • left, right, top or double hung hinges
  • overhead door closers
  • twin rod anti-panic exit locking system


  • coupling sections for joining steel secondary window units side by side or one above the other
Curved and Angled Hinged Secondary Window to Match the Existing, Secondary Glazing London

Secondary Glazing Bespoke & Special Units

Out of Square

Many windows in older traditional properties are out of square - in most cases these can be fitted with standard secondary glazing by shaping of the timber sub frame and the use of bespoke finishing trims.

  • where this is not possible, the secondary glazing can be manufactured out of square

Arches, Curves, Shapes, Colours, Glass & Film

Both modern and old windows and doors often have decorative arches, curves and shapes. It is important to match these often unique features with the lines of the internal secondary glazing.

  • to achieve this, we have the facilities to curve and bend sections as well as the expertise to produce angled secondary windows
  • additionally, we work with all sorts of specialist glasses and apply film to glass for security, tinting, etc.

We also offer:

  • the full RAL colour range for frame and panel finishes
  • Van Dyke Brown powder coated finish as a stock item
  • silver anodised finish from stock
  • specialist glasses - for security, UV filtration, tinted, coloured
  • film applied to glass - for security, UV filtration, tinted, coloured

Bespoke Secondary Glazing

We also produce, or modify our existing product range, to suit customer’s specifications - because of the setting up costs this is generally only feasible for larger commercial secondary glazing contracts.

  • If you have any special requirements please talk to us about them - we will always do our best to help you achieve cost effective, practical, functional secondary glazing solutions
In line with our policy of continuous product improvement & development London Secondary Glazing reserves the right to alter any of the product specifications without notice.

Further information:

Thank you for visiting - please Contact Us if we can be of any further help.