How to Successfully Maximise Daylight in Your Extension

Adding a greater amount of natural light into a new or existing living space is an essential part of any successful extension or loft conversion design.

By Larry Bohan on 28 May 2019

velux extension with four white roof windows

Alongside increasing space and value, creating a brighter and lighter room is often the driving factor behind most home improvement projects.

The importance of daylight to our health and need for less reliance on artificial lighting has come into sharper focus in recent years as a result of alarming findings on the amount of time people are spending indoors.

The most popular and well-known way of achieving a healthy and even flow of daylight at home is through a combination of vertical and sloped glazing. Less obvious, however, is knowing how many windows are needed to optimise these levels in order to really feel the benefits.

Here is an overview on best practice for daylighting home extensions and loft conversions, along with a few other ideas on how to turn your new space into the brightest, most welcoming area in the home.

How many Windows do I Need?

velux roof windows installed in kitchen

Be it a ground floor extension or loft conversion, the general rule we advise for effective daylighting is that a room's glazing should be equivalent to 15-20% of the whole floorspace at a minimum to ensure daylight hits the whole area.

With lofts, this is achieved most easily by installing rooflights into the existing roof structure. As long as headspace is no issue, adding roof windows to a roof that needs no further alteration is the less expensive and time consuming option versus a dormer extension.

A dormer loft extension might be your next best option if the basic rooflight conversion doesn't offer enough head height or floor space. 

Although the same 'floorspace÷5= glazing area required' formula is the same for extensions, getting daylight right can be trickier as the level of light provided by big sliding doors or bifolds can be deceptive in extensions.

It is important to remember that rear extensions can actually push daylight away from the original building, so complimenting your vertical glazing with pitched roof windows or flat rooflights is key. Roof windows, like those from VELUX, RoofLITE and ECO+, can let in as much as twice the daylight as vertical windows of the same size.

Combining pitched and vertical ensures an even spread of daylight at different angles, from dawn to dusk. With North facing extensions, getting this balance right is even more important as sloped windows can sometimes provide the only effective source of daylight.

This grid by VELUX highlights the glazed area measurements that each VELUX standard sized roof window will provide.



Five Tips for Getting the Most From Your daylight

Save Money with Fixed Windows-

If your project has already got a sufficient amount of ventilation provided by exterior doors or other vertical glazing, opting for non opening roof windows or fixed rooflights is a smart way of filling the space with daylight while saving a few pounds compared to the cost of manual or electric units.

Use a skylight to Highlight a Feature

By strategically positioning your roof windows or skylights in the roof you can draw people’s attention to a certain spot or prioritise an area of the room that is most used, for example a dining or play area.

Velux white roof windows in situ above staircase

Use Light Reflective Decor 

A clever way of making a room even brighter is with white/neutral coloured walls and decorative mirrors.  Adding light-reflective materials will help bounce light around the room, making it even lighter and airier.

korniche roof lantern in ground floor extension

Cut Back on Frame 

Pick modern rooflight designs with next to no frame, such as a contemporary roof lantern, to ensure there is nothing hindering the pathway of natural light into your extension or your enjoyment of the views up above.

Add Blinds

It might seem obvious, but blinds are a must-have when too much sun starts to become a problem. In loft bedrooms and en-suites they’re near on essential, while suitable extension rooflights will also need blinds to reduce glare.