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The Difference Between Flat & Pitched Roof Windows


12th July 2018

Understanding the difference between flat and pitched roof windows will ensure you make the right purchase to receive the full benefits they provide. For homeowners who have just converted their loft or installed an extension, we will explain the differences between the types of windows available and how they can help to improve your property.

If you are looking for an upgrade to replace an existing roof window we will also run through the various glazing options, the types of materials available to purchase and some general price points so you can assess how each one fits into your budget.

What Solutions are Available for Pitched Roofing?

There are numerous considerations to take into account when deciding upon the right roof window for a pitched roof. This will cover the type of room it is being applied to and how it should be opened. It also takes into account the type of glazing used and aesthetics.

Type of Room

If you are converting the loft into a new bedroom you need to think about the purpose of the window. For instance, if there is a nice view outside, you should consider a top-hung window that doesn’t obstruct this when opened. The VELUX GPU 0070 is one of the more popular versions. Top-hung windows of a certain size can be used for escape routes too.

Pitched Roof Windows - Roof Stores
Pitched Roof Windows

Ensuring the bathroom remains a private space to relax in comfort is a priority and one that obscure roof windows like the VELUX GPU 0034 are able to provide. There will be no restriction on the amount of light coming in while preventing any from seeing inside the room.

You may also want a window that is moisture resistant to combat high levels of condensation. This is especially important in rooms like the bathroom and kitchen. The VELUX GGU 0066 has no visible joins and leaves a moisture resistant finish. The ongoing ventilation of these rooms plays a key role in keeping down the onset of mould and damp.

Manual or Electric

Most roof windows are opened and closed manually by ensuring they are installed within easy reach, or by using an opening rod. Alternatively, there are electric options available which really add something special to the room. This is also an attractive option for elderly homeowners who are less mobile and require an easier way to control their roof window.

Opening Mechanisms

  • Centre-pivot roof windows: A popular option, with products like the VELUX White Painted GGL 2060 allowing the influx of more daylight and ventilation. These open at 180° from the middle, with half of the sash swinging up and back into the room, while the other end reaches horizontally outside.
  • Top-hung roof windows: This approach clears the frame from any obstruction and provides unrestricted views of the outside. The pivot is positioned at the top of the window. It is used by pushing the control bar at the bottom out and upwards.
  • Side-hung roof windows: These are less commonly installed but offer an alternative way of providing ventilation. Depending on the structure and layout of the roof around it, this may prove to be the more practical choice.


Laminated windows such as the VELUX GPU 0070 are a good choice for any roof windows positioned overhead height. If an object was to hit the window at force, a laminated window would not shatter and fall into space below. It will hold firmly in place and allow you time to source a qualified contractor to replace it.

Pitched Roof Windows - Roof Stores
Pitched Roof Windows

Frame Finish

The material and colour of the roof window also play a part in deciding on the best type available. White painted windows offer a clean and tidy finish to the decor. They also work well to counterbalance darker and neutral colours. Take a look at the VELUX White Painted GPL 2066 which comes with a clear white frame and is also triple glazed for enhanced sound insulation.

  • White polyurethane (PU): Windows like the VELUX GPU 0034 have become more popular over the past five years. They feature a timber core with a polyurethane cover and are one of the easiest windows to maintain post-installation.
  • uPVC windows: These offer many of the same benefits as polyurethane frames, although they come without a timber core.
  • Pine frames: For a more traditional look, pine window frames like the VELUX GPL 3066 add a more classic finishing touch to any exterior.

What Solutions are Available for Flat Roofing?

Flat roofs require a different type of roof window to ensure you receive the full benefits in the space below. As with a pitched roof window, there are several different aspects to consider before choosing the right one for your property. A flat roof window will be suitable for roofs with pitches between 0 - 15°.

Flat Roof Windows - Roof Stores
Flat Roof Windows


  • Glass-domed roof lights: This option combines glazing with polycarbonate. This produces a tougher exterior that works well on both residential and commercial properties. Their design also ensures rainwater doesn’t pool on the surface, which prevents the chances of condensation building up.
  • Flat glass roof lights: These remain one of the most popular choices as they come in a range of sizes and finishes while providing countless benefits to space immediately below. Installed correctly these will also prevent rainwater pooling due to the 2° stops.
  • Roof lanterns: An elegant alternative that adds a distinguished and unique look for any flat roof. Aluminium trim separates the various glazing pieces to create a pitch in modern lanterns. Timber is used in more traditional styles. There is no limitation on size or dimension with many lanterns even made to measure if required.
  • Walk-on roof lights: These are the perfect solution for terraced houses that experience foot traffic during the summer months. It enables homeowners to receive the benefits of a roof window while also providing a direct access point to the surface of the roof.
  • Polycarbonate domes: This can either be purchased as single, double, triple or quadruple, depending on requirements. Polycarbonate domes are made from one of the strongest materials available, considered to be almost unbreakable. This should be considered by those with security concerns.

Opening Methods

  • Fixed roof windows for flat roofs: These are a good option if the room below already has a good source of ventilation. A non-opening window will still be a strong source of light. It's a more affordable option for those working on a tight budget.
  • Manually controlled flat roof windows: This option is operated either by hand or an opening pole, depending on how easy it is to access. This is the most common type of roof window due to its cost-effectiveness.
  • Electric windows: Run by remote control, this approach adds a modern feel to the home. There are some available that come complete with a rain sensor or timer options. They are available in nearly all types of materials and styles.

Planning Constraints

In most cases, you will not need to seek planning permission to install roof windows. This is because it falls under the permitted development rules. These allow homeowners to make alterations to their homes based on the following:

  • Side-facing windows must feature obscure glazing with an opening 1.7m above the floor.
  • Any alterations are made no more than 150mm from the current roof plane.
  • There can be no alterations made which are greater than the highest part of the roof.

Solutions for Flat Roofing - Roof Stores
Solutions for Flat Roofing

Lifespan Expectancy

This will depend on the quality of the installation. It also relies on how well-maintained the roof window is and the immediate environment surrounding the house. If your window picks up dirt easily because the air in the region contains a high number of pollutants, this will require cleaning on a more frequent basis. You will also need to clear any blockages in the collar and flashing so rainwater can continue to flow freely off the roof.

Most branded roof windows come with a 10-year guarantee as standard. However, if you put a regular cleaning schedule in place and ensure any damage is repaired quickly your roof windows are likely to last far longer.


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