Glass Units

Order Thin Sealed Units below

Order Bespoke Slim Sealed Glass Units Online

At Sealed Units Online we pride ourselve on quality Sash window double glazed units with great customer service. Our online Sealed Unit service is designed to allow you to easily order slimlite glass sealed units for sash windows direct from the manufacturer - minimising admin to lower costs. Our service is backed up by experienced craftsmen and the latest in technology.

Inner Glass
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We currently only offer 4mm Softcoat and 4mm Clear for the Inner Glass option.

Cavity Width
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Spacer Bar
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Krypton Filled - Now choose your Cavity Width. We offer 4mm, and 6mm Cavity Options. Please note that larger sized units are only available with a wider cavity

We even have options on what colour Spacer Bar is required. Our current options are White, Black or Silver.

Outer Glass
Please Select
Please Select

Unit Dimensions W x H

We currently only offer 3mm Clear and 4mm Clear, for Outer Glass options.

Toughened glass is used when safety, thermal resistance, and strength are important considerations. Breaks into small cubes to minimise injury.

 mm x H  mm 
Price £30.24  Add To Order

5. Are thin glazed units suitable for both residential and commercial properties?


Slimline Double Glazed Units are used predominantly for the residential market but some prestigious offices and shops may also have a requirement for thin Double Glazed Units.

6. What is the cost of thin glass Units?


Costs vary depending on the spec and size of the unit. There is however a minimum chargeable area, so the price doesn't start to increase until it exceeds 0.3 of a square metre.

7. What is the thinnest slimline unit that can be manufactured?


The thinnest unit that can be manufactured is just 10mm in thickness. This is made up of 2 x 3mm panes of glass with a 4mm spacer bar. However, this is not the best performing unit for two main reasons.

Firstly, 3mm glass does not have the heat reflective coating (low E) unlike the 4mm Softcoat glass.

Secondly, the 4mm spacer bar is the thinnest available and this restricts the amount of Krypton Gas used to fill the cavity. So, in short, the thicker the unit the better the performance and 4mm Softcoat or 4mm Planitherm inner glass is greatly beneficial in the improvement of thermal insulation.

If the thickness is a real problem as you are restricted by the rebate on your frame then we strongly recommend an 11mm unit to include the 4mm Softcoat inner pane.


1. What are thin slimline glazed units?


Thin slimline units are to replace glass within windows to improve insulation within the property and where the frames are made from timber and do not allow for thicker cavity double glazed units due to a restricted rebate.

2. What are the benefits of using thin glazed units?


When replacing single pane glass with a slim double-glazed the cavity of the unit will be filled with gas which acts as insulation reducing the amount of heat lost within a property, helping to lower heating costs. There is also the benefit of noise reduction creating a more relaxing and comfortable environment.

3. How do thin glazed units improve energy efficiency?


Thin double-glazed units improve energy efficiency due to two main characteristics. Firstly, the use of a visually transparent reflective coating which reduces thermal transfer and secondly the cavity of the unit is filled with in most cases Krypton Gas further reducing the thermal transfer between inside and outside the property. This is measured as a U value. The lower the U value the better the thermal performance.

4. Do thin glazed units reduce outside noise?


A double glazed unit will help reduce outside noise within the property but there are some things to consider if this is of importance to your situation. For best results in noise reduction select 6.8mm Acoustic Glass on the outer pane along with either 3 or 4mm glass on the inner pane. The two thicknesses of glass in a single unit will help cancel down noise across a larger frequency scale.

Many thanks to Sealed Units Online. You have helped us to turn our draughty old Victorian house into a much warmer place to spend the winter! The whole ordering process was extremely simple with the very accurately made glass units arriving on time and in perfect condition. Great work! Thanks!


Andy D, Oxfordshire


I purchased over 20 sealed units to change all of the glass in my house. Delivery was quicker than expected and all units were to specification, including different thicknesses, different spacers, some toughened glass, some obscured, some clear. I enjoyed using the website, ordering was easy with the help of Customer Services, in all a good experience.


Keith R, Midlands

SealedUnitsOnline Van



We offer a full UK delivery service on all sealed units.

Option 3 DAY* - £180 any location within Mainland UK.

Option 7-10 DAY* - £60 any location within Mainland UK.

Option upto 14 DAY* - £30 any location within Mainland UK.

Option upto 21 DAY* - £15 any location within Mainland UK.

Option upto 28 DAY* - FREE any location within Mainland UK.

Please note that our delivery options are an 'upto' service this means in most cases our deliveries are made much earlier than the amount of days selected. However this is not guaranteed but merely a guidline. Operating our own delivery service we ensure your Glass Units arrive in perfect condition. For orders outside of UK please contact us so we can help calculate a price and arrange with a preferred ferry shipping company.

*3, *7-10, *14, *21 or *28 full 'working' days. Any special requirments can result in additional delivery time. This will be advised shortly after placing the order. Prices for delivery are subject to VAT.


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