Contact us: 0203 633 3224

Our bespoke Stepped Integrated Sealed Units (IGU’s) are perfect for visually expanding areas such as hallways, stairwells, and other closed-in dark spaces that can be transformed with daylight and sky views. The seamless design with no joints ensures protection from water accumulation and mould build up.

TGS Skylights let in twice as much light as vertical windows and will make a great impact on your living environment. High quality materials are used in manufacturing our roof lights to ensure the product is attractive and economical with excellent thermal performance. All our sky lights or roof lights are custom made to customer specifications to meet the desired u value required to comply with building regulations.

Additional images showing various fixed sky light and flat roof light types we supply can be found in the skylights photo gallery section of our website.

Unlike some of our competitors, this stepped rooflight system has been through independent UKAS accredited testing and met the requirements for Air Permeability (EN12207) and Water Tightness (EN122008). Indicative independent tests also performed to the same requirements as PAS24-2016 C.4.4.3 Mechanical Infill test -2kN loads applied at the corners of the glazing aperture, no entry was gained and there was no breakage or deformation of the product.

Price match guarantee

We want you to get the best price for your purchase. This is why we promise to match the prices of other UK retailers.

High Quality Materials

High Quality Materials

High quality materials from reputable suppliers such as Pilkington glass are used in manufacturing our skylights to ensure the product is attractive and economical with excellent thermal performance.

Building regs and performance

The rooflight Stepped Insulated Glazed Unit (IGU) we supply are suitable for flat roof extensions and double story extensions to existing dwellings. As each project can vary with requirements, we suggest confirming building regulation requirements for the product with the architect, builder or building officer prior to placing an order to ensure compliance. For example, it may need to be obscure, triple glazed, bigger upstand, suitable for walking on, etc.


Standard units

Standard units

Our standard units are double glazed with clear toughened glass top pane manufactured to BS EN 12150 and conform to BS EN 1279, 18mm argon-fill cavity structurally sealed with and toughened Low-E glass to achieve a centre pane 1.2 u-value.

Triple and quad glazed units

Triple and quad glazed units

Our triple and quad glazed options provide even higher performance ratings. 1.6 minimum U-value rating is currently required to comply with building regulations. The solar control layers prevents heat escaping and reflects interior heat back into the room.

Optional Extras

Coloured boarders – If required we can paint any RAL colour to the boarder which is usually 100mm wide all around.

Pilkington Activ self cleaning glass – Applied coating breaks down dirt and washes away with rain water.

Pilkington Activ blue self cleaning glass – In addition to self cleaning properties the blue tint provided additional solar control performance by keeping internal temperatures cool whilst maintain light transmission.

Triple glazed skylights – achieving 0.9 centre pane U Value rating.

Privacy glass – We can apply a sandblasted frosted layer to make the skylight obscure.


Standard delivery 7–12 days
Standard manufacturing lead time for custom made flat roof skylights is 7–12 working days depending on the specification. Delivery will be made from 7am to 5pm

We provide a delivery date within 3 days of processing the sale. In the London and surrounding area we usually deliver for free on the same day manufacturing completes.

National delivery lead times will vary. You would need to ensure labour is made available on site to off load the glass from the van. Alternatively we can offer pallet delivery at an additional cost depending on the area.

Easy fit


Our roof light Stepped Insulated Glazed Unit (IGU) installation can easily be undertaken by competent builders/roofers and we provide simple step by step fitting guide and technical support to facilitate installation.
The Stepped IGU supplied can be installed directly on the Upstand made by the builder or roofer supported by 20mm by 20mm timber battens all around.

All information and diagrams on this page are for guidance only to install the Stepped Insulated Glazed Unit (IGU) we supply as each project may vary in design/construction as per architects’ drawings. Upstand design and dimensions can vary based on architects approved drawings and insulation requirements. The Stepped Insulated Glazed Unit (IGU) can be custom made to suit wider upstands with bigger than 100mm overhangs if required at additional cost.

Contact us

Telephone: 0203 633 3224

TGS Skylight Thermal Ratings

Standard Double Glazing

Standard Double Glazing

Standard Triple Glazed Specification

Standard Triple Glazing

Installation and Measuring Guide

Our skylight installation can easily be undertaken by competent builders and roofers. We provide simple step by step fitting guide. For technical support please contact 0203 633 3224.

1. Measure the opening
2. Preparing your roof
3. Installing the skylight

Measure the opening

The first step in purchasing your Stepped Insulated Glazed Unit (IGU) would be to measure the structural opening where the stepped unit will be installed. You should allow for 5mm tolerances all around to allow the bottom pane of the Roof Light Stepped Unit to fit smoothly into the opening. As an example, if your tight opening measurements are 1010mm by 1010mm we would recommend you purchase a skylight Stepped Unit with a bottom pane of 1000mm by 1000mm so it slots in smoothly.

For standard units the top pane would have a black 100mm overhang all around on the top pane. This would make the overall size of the top pane 1200mm by 1200mm in this example. We can increase the size of the overhang if required if upstand width is wider. The diagram below shows the sectional view of a double-glazed installed Stepped Insulated Glazed Unit (IGU).


Preparing your roof

Structural glazing silicone is to bond the double/triple glazed sealed units to the top pane to form a stepped unit. The Stepped Unit IGU is simply be secured onto the timber kerb built by your roofer/builder as part of the roof construction.
The timber upstand should protrude 150mm above the roof. The pitch should be 6 degrees, sufficient to allow water to flow down.



Installing the skylight

The final step to finish the roof before installing the Stepped unit is to apply your roof covering on side the of the upstand to make it weatherproof as illustrated below.

The timber upstand should protrude at least 150mm above the roof and the pitch should be 6 degrees, sufficient to allow water to flow down. Before sealing the product with silicone, water can be applied to test the flow off of water, if pooling occurs a higher pitch may be required.

Bottom pane should be supported by timber battens on 4 sides once set in place, this can be fitted to align with the plasterboard wall or protrude from the wall.


Apply adequate compatible low modulus silicone as per silicone supplier’s data sheet to the top of the Upstand and once cured apply structural silicone to the timber batten flat surfaces firmly positioning the Stepped Unit IGU onto the Upstand, finishing off the silicone all around. Pressure should then be applied all around the 100mm overhang to ensure the silicone spreads and seals any gaps. Excess silicone should then be wiped away with a finishing tool. Dowsil 791low modulus weather proofing silicone is compatible with Dowsil 3363.

At this stage the bottom pane should be supported with timber battens on 4 sides and can be made flush with the wall using plasterboard resulting in a finish similar to the picture below.
A sealant compatible with the top of the upstand, glass and Dowsil 3363 silicone should be used. Some sealant suppliers may require primer to be applied to non-porous surfaces.
Please note all Stepped Units are made to order and sizes can not be changed once glass is cut or toughened. We recommend the speciation, sizes and instructions are reviewed and understood by the installer before proceeding with and order.


For Skylight Installation, Replacement and Cost Inquiries please contact us

How Much Does It Cost?

The actual cost will depend on the size and specification of the product. Fill in the form below and we will be able to give you an exact quote for your project. The more information you can give us the better, but do not worry if you do not have all the information to hand.

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