A 4mm piece of single glazing will offer a centre-pane U-value of Approximately 4.5wm2k.

Glass and Glazing has evolved dramatically over the years from Single Glazed Sash Windows. The industry has gone around in Loops regarding Certification and Red Tape. However, we are always Researching and keeping up with Legislation. To simplify things our specification remains the same regardless of option the only change is the cavity width and what insulating gas/medium it is filled with. The space in between glass panes can be 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm or 20mm. Below are the common options available to you above (Standard – Single Glazing).

24mm Double Glazing - Planitherm Comfort +

Our standard go to Double Glazed Glass Unit Is the 24mm Planitherm Comfort + / LowE Unit. Make-Up 4/16/4. Argon Filled with Optiwhite Warm Edge Swisspacer Bar. Soft Coat Inner Pane. Centre Pane U Value of 1.1W/m2K. Sound Reduction Factor Rw 31 (-2; -5) dB. This glazing option is Industry leading and provides the most results regarding Noise/Heat retaining properties.

Alternative Double-Glazing Options – (Argon Filled)

20mm Double Glazed Units – Our 20mm & 18mm Units offer a slimmer profile for those less worried about performance but more the thickness of Glass. These will create a slimmer sightline and make the windows appear more like their Original Predecessor – The Single Glazed Sash Window. Both Units are still FENSA Compliant and meet Part L of FENSA Regulations. Having a U Value of 1.4W/m2K or Below.



Lower still regarding performance but thinner in appearance is our 16mm Units. Due to variation and our safety Margin regarding FENSA Compliance, if seeking certificates these units will have to be approved by a local council and/or Building Regs. Their U Value comes very close to the threshold of 1.4W/m2K And therefore make these units Non FENSA Compliant

12 or 14mm Heritage Double Glazed Units – (Krypton Filled)

Often presents the case where Local Councils issue Article 4 Directions – Removing the right from a homeowner to replace like for like Timber Sash Windows with Double Glazing in a Conservation Area. This is usually due to them having to approve Glazing Unit Thickness v Energy Efficiency. In certain cases, they may approve one of our Standard Thickness units (24mm, 20mm or 18mm) or specify the use of a Slim Line Heritage Unit or Simply in extreme cases permit the Replacement back in Single Glazing.

Our Heritage Units are available in 12mm or 14mm.To boost the Energy Efficiency of our Slim Line Heritage Range we use can Krypton Gas as a Cavity Medium. Which unfortunately does increase the price of the glass significantly. Argon Gas is still useable just with lower heat retention properties.

Cavity Gasses & U Value

By filling the space between Double Glazed Sealed Units with an Inert Gas instead of Air we can significantly improve the energy rating of Double-Glazed Units. As standard we fill our units with Argon and our Heritage Range Units with either Argon or Krypton but there are other gasses available to increase efficiency further.

The Gasses are:

  • Argon
  • Krypton
  • Xenon
  • Special Gas

Planitherm Comfort +

Comfort Plus glass provides the perfect balance of light, warmth and comfort. An invisible coating blocks out 50% of external heat from the sun while keeping in 63% more internal heat*.

It’s ideal in sunny south- and west-facing rooms or for large glazed areas such as bi-fold or patio doors, making your home cooler in summer and warmer in winter.

A built-in transparent layer also makes Comfort Plus harder to break through and provides up to 20% better noise reduction than older-style double glazing* so you’re sure of a good night’s sleep. It can even protect furniture from fading, blocking 99% of damaging UV rays**.

*Compared with a 4mm/16mm cavity/4mm (uncoated) Double Glazed Unit filled with air
**Calculated from UV transmittance in accordance with EN 410

Features of Comfort Plus

ENERGY EFFICIENCY – With Planitherm, energy efficiency comes as standard.

A special coating on our glass helps stop heat escaping, so you’ll use less energy to keep your home warm. Our Energy Standard and Comfort glazing captures and makes use of the warmth from natural daylight, while Comfort Plus helps limit and control it – ideal for very sunny rooms.

ENHANCED SECURITY – Helps protect your family from break-ins and vandalism.

Our high-security transparent layer on Comfort and Comfort Plus glass makes them much tougher to break through than standard, unlaminated glass. Used in an approved window frame, they’re designed to meet the official police security initiative ‘Secured by Design’ standard, so you’ll feel safer and more secure in your home.

NOISE REDUCTION – Make your home a peaceful respite from the world outside.

Perfect for bedrooms to ensure a good night’s sleep, a built-in acoustic layer keeps exterior noise exactly where it belongs – outside. If you live on a busy road or close to other disturbing sounds, noise control glazing should be on your list.

FURNITURE FADE PROTECTION – Keep your furniture looking newer for longer.

Prolonged exposure to ultra-violet light from the sun will contribute to your furniture and curtains fading over time. Our hidden layer of protection on Comfort and Comfort Plus glass blocks out 99% of the sun’s UV rays. Think of it as sun-block for your sofa, curtains and carpets!

REDUCE OVERHEATING – Perfect balance of light and warmth.

Rooms with lots of glass will give you a great view, but the warmth from natural daylight can make it uncomfortably hot on sunny days. Our Comfort Plus glass has a special coating designed to keep out heat from the sun’s rays, for a comfortable, bright environment and greater control of your internal temperature. It’s particularly suited for south- and west-facing rooms with sunny aspects, or larger glazed areas such as bi-fold and patio doors.

Toughened / Safety Glass

No detail is to small for us. Especially when Legislation is concerned. As absolute standard any window below or even close to 800mm from the internal flooring is supplied in Toughened Safety Glass. The Tough Plant usually adds a 4 day wait to our units – However this heating process makes the glass extremely strong. Secondly if the glass did break it would shatter into thousands of pieces removing the hazard of getting cut by large shards of glass.

Single Glazing

Sometimes the solution to repairing a window is simple and all that is needed is the sashes replaced. We can do this and replace single Glazed Glass. The technique involves one of our Glaziers re-putty fronting the glass into the sash. It is becoming an old trade as the use of timber beds are used more frequently but we are proud to still use these techniques

6.4mm Laminated Glass

Often we are asked by clients if we can provide a more secure glass to our Single Glazed Sash Windows. And the answer is Laminated Security Glass. If ever smashed it is laminated – keeping all the pieces intact. Often this prevents the glass window being put through and prevents access. It also makes for a far safer option.

Acoustic Glass

Customers whom live on busy roads where there is significant Road Traffic for example may be interested in replacing their windows with Double Glazed Acoustic Glass. The decibel rating here is improved by incorporating Laminated Glass into the make up of the unit.

Obscured Glass

Commonly asked for by clients in their Bathroom/ Toilets or perhaps where the room might be slightly overlooked is the need for obscuring the glass. Our go to is the Frosted Satinova look as we believe it looks Smart and Modern but if you prefer something special, we can certainly accommodate. Some examples are shown below:

Soft Coat Technology

Low e glass has a special coating applied to one of the internal Glass face called ‘soft coat’. The low E coating on the glass allows most of the visible light to pass through as well as the short-wave heat energy but blocks long wave energy from passing through. This ensures the heat from inside the building is reflected into the room and so heat losses are significantly reduced.

White Warm Edge – Swisspacer Bar

Within the Make-Up of our units we ensure we use the best materials possible. Available technology consists of Warm Edge Spacer Bars. These spacers are made from insulating materials when in turn used insulates the cavity within Double Glazed Sealed Unit.  Warm Edge Swisspacer reduces the Overall Glass Unit U Value by 0.1W/m2k. This is how we achieve a U Value of 1.1w/m2k in our 24mm Option.

We also ensure our spacers are white in colour – seamlessly matching the timber so when you look through our windows nothing is a miss. The eye doesn’t even notice the windows are Double Glazed too easily.

Leadlight Units

We can source and glaze leadlights of all varieties, colours, shapes and size to suit all budgets and timber products.

We have some fantastic partners who we regularly work with to design bespoke hand made lead light designs or we can supply and glaze our standard simple traditional leadlights on the outer pane of our double glazed units.