A guide to VELUX flat roof windows

Flat roof extensions are more popular than ever! they make a home feel spacious and provide that essential extra space for a growing family.

While the benefits are clear, you need to consider how the flat roof extension will affect light in the rest of the house. Then how your structure can best incorporate windows to compensate. Finding the perfect balance between position, size and number of windows is key to getting this right. VELUX offer a wide selection of flat roof windows that will enable you to achieve this.

Lighting considerations

For homes that are lucky enough to be extending on a south facing elevation, in order to avoid harmful UV exposure and overheating, we recommend limiting the ratio of rooflights to floor area. Thereby providing enough light without the discomfort of overheating during the height of summer.

The right number, type and size of windows will help avoid dark spaces and will be key to a successful flat roof extension.

Whilst bi-fold and patio doors look great, extending into the garden moves daylight further away from the original house. Homeowners don’t want to end up relying on artificial lighting in the spaces that light from the bi-folds just can’t reach. Bring more natural daylight into these spaces, whilst increasing space and improving ventilation in the extension, with the perfect VELUX flat roof window.

Flat roof window options

Flat roof domes and windows have come a very long way since the early days when people worried about how they looked or even if they’d leak! Choices now include a fixed or electrically operated vented base unit, flat or curved glass along with the more traditional roof domes. If these options are not enough VELUX have also incorporated their pitched roof windows into the flat roof range using their Flat Roof Kerb.

There are also a range of glazing options to choose from, and triple glazing is available for optimal energy efficiency. Solar reflective glass can be specified, or glass with a low g factor, such as VELUX’s Glazing 60, which keeps the solar radiation levels down to as little as 30%.

Simply the glazing accounts for a large amount of a flat roof extension budget, so you want to get it right!

More about our VELUX flat roof windows range:

Curved glass rooflight —suitable for pitches 0°-15°

The Integra is the world’s first ever flat roof window with curved glass. It lets rain run-off preventing water from pooling or staining the glass, meaning it’ll stay clean for longer. This is the premium choice for homeowners with it’s stunning edge-to-edge glass design, which looks great from the outside and is brighter inside.

Combi Flat Roof System

Combi Flat

Roof System

A practical solution to the installation of two or three windows in a flat roof. The system is completely pre-fabricated for ease of installation on-site.

Features

• Keylite Flat Roof System comes complete with a shaped, insulated wooden kerb and flashing kit.
• Combine with your choice of Keylite roof windows (priced separately) for a complete ready to install solution.
• To maximise the amount of natural light entering the room, the front and back framing is angled.
• The system is also available with Keylite Electric Operation and Smoke Ventilation Systems.

Installation

• For the installation of roof windows over 2.2m, Keylite also recommends an electrical control unit and laminated inner pane.

Finish Options

Choose the perfect finish for your Keylite Roof Window. Our Roof Windows come in three different finishes: Polar White PVC, White Painted Pine or Clear Lacquered Pine.

Polar White
PVC

White Painted
Pine

Pine Clear
Lacquered

Expanding Thermal Collar

Just pull the tapes and the foam expands to fill the gap between the window and the roof timbers

Keylite Roof Windows all provide trickle ventilation, even with the window fully closed and securely locked.

The built-in insect filter ensures only clean, fresh air passes into the room.

Achieve finger-tip control, to give maximum control over ventilation and shade.

Explore

Simple, Easy.. Fast. From box to roof in 2 minutes. Keylite innovations combine for faster, easier installation.

All our roof windows are recessed for an in roof look.

All our roof windows are recessed for an in roof look.

Flat Roof Window Buying Guide

Choosing the right roof windows for your flat roof extension can enhance your new space no end as the natural light that funnels in from the window opens the room up, creating a fresher and healthier living environment.

Our flat roof window guide will help you decide which type of rooflight is best suited to your needs and will explain everything you need to know regarding glazing, operating methods and energy efficiency.

Rooflights for flat roofs

What is the best kind of rooflight for my room? There’s a balance between visual appeal and choosing the right material for the job. We’re here to help you choose.

Flat glass rooflight

Flat glass rooflights are one of the most popular flat roof windows on the market. An ultra-modern design mixes style with efficiency, meaning you can give your home that wow factor while saving on energy bills and enjoying comfortable levels of insulation.

Known for their brilliant energy performance, ECO+ have flat glass rooflights that come with built-in LED lights, available in a host of colours to fit any theme.

VELUX’s curved glass rooflight would be a showpiece item in any room, while also lowering maintenance needs with its curved top providing natural drainage.

Flat glass domed rooflight

For long a popular choice on both residential and commercial roofs, flat glass domed rooflights are made using at least two layers of glass covered by a single skin dome, formed in a high insulation PVC frame.

The substantial list of benefits of flat glass domed windows include; reduced maintenance, high energy efficiency and effective sound insulation. FAKRO offers a quadruple-glazed rooflight for additional sound insulation and even greater energy efficiency.

The window is suitable for installing on roof pitches between 0° and 15° and comes in fixed , manual and electric operating styles.

Lanterns

Contemporary roof lanterns consist of glazing pieces separated by aluminium trims that meet in the middle to form a pitch. The stunning views they offer of the sky above are sure to astound all that look through.

Lantern rooflights have the much-desired effect of making your room appear bigger due to the impression given of a higher ceiling. They come in a number of different pre-set sizes but can also be made bespoke to fit flush with any design.

Lanterns come in fixe d , and manual operating styles and are available in double glazing as standard, with triple glazing alternatives available for added energy efficiency and noise insulation.

Walk-on rooflights

Manufactured using a one-piece s tainless steel design, walk-on roofligh ts are an extremely popular choice for basement conversions as they are a practical solution to introducing natural light into areas that the sun struggles to reach.

Walk-on rooflights are made to withstand a great deal of weight and feature an enhanced grip and safety coating that prevents slipping in wet conditions.

The rooflights are available in all levels of glazing while the exact dimensions of the window can be made to order so to fit your designs.

Available from FAKRO and Signature .

Polycarbonate domes

Polycarbonate domes are the most affordable flat roof window option and are ideal for outbuildings and large commercial developments. Despite their cheap price, roof domes offer a number of benefits to your home.

With an impact strength that is up to 250 times greater than that of glass, polycarbonate is as close to unbreakable as you can get with a roof window.

Good quality polycarbonate domes with a UV-absorbing surface layer should be resistant to discoloration at the same time as maintaining light transmission.

How would you like your window to operate?

Fixed/non-opening

Non-opening/fixed rooflights are a smart option to save a lot of money when ventilation is already provided from other sources. The perfect option of adding natural daylight to extensions and garden rooms.

Manual

Manual flat roof windows are a very good choice for homeowners looking to ventilate their home. Offering the same levels of fresh air flow as electric rooflights, manual roof windows can be opened by hand or with an opening rod .

Electric

The most contemporary and flexible way of opening a roof window. Controlled via a wall switch, remote control and even mobile phone, electric rooflights have become a popular choice for the modern homeowner.

Clear/neutral

The finish of choice for most flat roof windows, clear glazing offers uno bstructed views of the sky above. Unlike clear glazing, neutral glazing is not fully clear as the protective coating on the glass produces a slight tint.

Neutral glazing is available on both Korniche and REAL lanterns , while clear glazing can be applied to most of our flat roof windows.

Obscure

A sensible choice for bedrooms, bathrooms or anywhere else where your private space is important, obscure glazing is designed to offer complete privacy and achieves this by making it impossible to see in or out of when closed.

Signature are specialists in obscure-glazed rooflights, offering a large range of size s in fixed, manual and electric operating styles.

Blue tint

If you are worried about the effect of the sun on your new sofa, subtle blue tint glazing can reduce harsh glare and protect furniture from fading.

The add ition of a blue tint can also create a blue sky feel, perfect for fixed windows. REAL has a number of lantern sizes available with blue tint.

Bronze tint

The main purpose of bronze tint glazing is the same as blue tint- helping to reduce glare from the sun and thus protecting your furniture from fading.

Too much glare can also make pleasurable activities such as reading a book or watching TV harder to enjoy, a problem that bronze tinted lanterns offer the ideal solution to.

Which type of window glazing is best?

Double glazing

The industry standard. Two layers of glass separated by an inert glass for improved energy efficiency. Double glazed rooflights can provide outstanding thermal performance when built in a thermally broken design with low-E coating.

Triple glazing

Made with a third pane of glass for superior insulation. The energy performance o f a window can be measured by its U-value. The lower the value, the better the insulator. FAKRO triple glazed flat glass rooflights come with a U -value of 0.88 W/m²K.

Quadruple glazing

A fourth layer of glass makes quadruple-glazed flat roof windows suitable for passivhaus projects. FAKRO lead t he way in this market with a range of eco friendly rooflights. The U-values on FAKRO units go as low as 0.58W/m²K.