Glazing for loft extensions

Extending up is one of the most popular home improvement projects that’s seen across the UK. It comes close to the popularity of single and double-storey extensions at the rear of properties, but roof and loft extensions help to ease space pressure on the rest of the home without having to use valuable land.

Most loft extensions usually fall within the Permitted Development, but planning permission is always required when carrying out any work to a listed building or a building in a conservation area – and building regulations need to be adhered to. Whether the loft extension is to become a bedroom, office, additional living room or perhaps a cinema room, the structure of the existing roof will need to be taken into consideration as well as the glazing and a loft conversion staircase.

Frameless windows to create modern loft extension

Does a loft extension / loft conversion need Planning Permission?

In most cases, loft extensions are usually categorised as Permitted Development however the extension plans will need to adhere to several conditions. Permission is required when the roof is extended or altered and exceeds the specified limits and conditions according to “the enlargement of a dwelling house consisting of an addition or alteration to its roof” as detailed in Schedule 2. Part 2, Class B of The Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended).

 

A loft conversion is considered as permitted development (which means it doesn’t require an application for planning permission) as long as it adheres to the following limits:

  • A volume allowance of 40 cubic metres additional roof space for terraced houses*
  • A volume allowance of 50 cubic metres additional roof space for detached and semi-detached houses*
  • No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway
  • No extension to be higher than the highest part of the roof
  • Materials to be similar in appearance to the existing house
  • No verandas, balconies or raised platforms
  • Side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor
  • Roof extensions not to be permitted development in designated areas**
  • Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the original eaves
  • The roof enlargement cannot overhang the outer face of the wall of the original house.
An Umbris Louver Roof used on the upper floor of this residential block to protect the patio living space.
architectural glazing to a new house

* However, this also includes previous additions to the roof which must be included within these volume allowances. This includes additions that have been made before your client occupied the property.

** These designated areas refer to Areas of Outstanding Natural Beauty, conservation areas, World Heritage Sites, the Broads and national parks.

These Permitted Development allowances refer to houses and not; flats and maisonettes, converted houses or houses that have been created through Permitted Development rights to change use or areas where there might be a planning condition that restricts the limits of Permitted Development rights.

If the loft extension design extends beyond the limits and conditions of Permitted Development, or the property is situated in one of the designated areas (as mentions above) then a planning application will need to be submitted. Planning permission is also required if the height of the roof is going to be adjusted or if the shape will be altered (this usually occurs in properties where additional headspace is needed).

What are the Building Regulations for loft extensions?

For loft extension and conversions, the works will need approval from Building Regulations. This will entail several inspections by a building control surveyor at various stages of the project, and finally an issue of a completion certificate on the final inspection.

Building Regulations Parts L, K, B and P are the parts that are likely to be the most important parts to focus on when it comes to loft extensions.

Building Regulations Part L focuses on the requirements for the U-values that need to be met when a loft is converted into a habitable space.

Building Regulations Park K is the section that ensures that there are preventative measures in place for falling, collisions and impact. This part also ensures that there is a minimum headroom of 2m in loft conversions and loft extensions where there are escape routes. However, the headroom requirements are a little relaxed for the stairs leading from the loft down to the main house.

Building Regulations Part B and P concerns the fire and electrical safety respectively. The Building Regulations for fire safety can be a very complex task that requires careful planning. In a property that is two or more storeys (where an escape window would be installed 4.5m or more from the ground) a protected staircase needs to be a safe exit route. A protected staircase means a staircase that offers protection from flames and heat in the event of a fire.

The Party Wall Act applies when there is a shared wall with a neighbouring property that will be affected during construction works, which is usually the case for terraced, semi-detached houses or flats. A loft conversion that includes cutting into a boundary wall (which could be to support new structural beams) is covered by the Party Wall Art.

What are the Building Regulations for loft extensions?

For loft extension and conversions, the works will need approval from Building Regulations. This will entail several inspections by a building control surveyor at various stages of the project, and finally an issue of a completion certificate on the final inspection.

Building Regulations Parts L, K, B and P are the parts that are likely to be the most important parts to focus on when it comes to loft extensions.

Building Regulations Part L focuses on the requirements for the U-values that need to be met when a loft is converted into a habitable space.

Building Regulations Park K is the section that ensures that there are preventative measures in place for falling, collisions and impact. This part also ensures that there is a minimum headroom of 2m in loft conversions and loft extensions where there are escape routes. However, the headroom requirements are a little relaxed for the stairs leading from the loft down to the main house.

Building Regulations Part B and P concerns the fire and electrical safety respectively. The Building Regulations for fire safety can be a very complex task that requires careful planning. In a property that is two or more storeys (where an escape window would be installed 4.5m or more from the ground) a protected staircase needs to be a safe exit route. A protected staircase means a staircase that offers protection from flames and heat in the event of a fire.

The Party Wall Act applies when there is a shared wall with a neighbouring property that will be affected during construction works, which is usually the case for terraced, semi-detached houses or flats. A loft conversion that includes cutting into a boundary wall (which could be to support new structural beams) is covered by the Party Wall Art.

Slim framed sliding doors lead from a loft conversion bedroom to small balcony

What are the best windows for loft conversions?

Loft rooms tend to be very spacious areas that usually provide the best views as they are right at the top of a house. Their spacious design is highly sought after as they often have vaulted ceilings, exposed brickwork or exposed beams. Whether the property is in the city or the countryside the property is afforded outstanding views, so the window choice is very important to get right.

What are the best window options for loft extension designs? The exact window option will highly depend on the planning permission, the type of loft extension and the layout of the property. Rooflights and Dormer windows can be installed under Permitted Development to provide additional natural light into loft extensions, but they cannot extend forwards of the roof plane and they must not be taller than the existing height of the roof (the refers to the highest part of the roof).

One option for creating a unique loft conversion is adding an automated rooflight system. The MARS is unrestricted on size and opens with the click of a button, introducing ventilation and natural light into loft spaces. The bespoke system has been developed in house to deliver specialised results every time. For unparalleled performance values and a minimalistic design, specify the MARS electric rooflight.

Dormer Windows

In the UK, dormer windows are one of the most popular types of windows seen in loft conversions and loft extensions. They are designed like a raised box shape that protrudes out of the original roof of the property. They are popular as they provide additional headspace and usable floor space in lofts which usually have low or sloping ceilings.

Dormer windows occasionally do not require Planning Permission, but it depends on the specifics of the property. Some local authorities have restrictions when it comes to adding dormer windows to homes in the area, for example, sometimes the dormer window has to be constructed using materials that match the rest of the façade of the building.

Rooflights or skylights

Rooflights can be a clever way to flood loft spaces with natural light as the follow the slope of the roof. However, because the rooflights follow the roof's angle they do not maximise the view of the surrounding landscape as they are angled towards the sky. If the homeowner is looking to maximise their views from their loft, then skylights or rooflights are not the best options to achieve this. If the view isn’t desired, then this glazing option will provide abundant light into the loft.

Gable-end windows

Gable-end windows are an impressive installation within loft conversions and loft extensions. The gable-end (the triangular upper section of the side of a property that has a ridged roof) can provide an impressive influx of natural light while also creating stunning views of the surrounding area. In some instances, it may even be possible for a Juliette balcony installation to the gable-end which will further enhance the views of the surrounding area.

Modern loft conversion
Loft conversion bathroom

Fire safety in loft extensions

Glazing for loft extensions often come into play with fire safety requirements for loft extensions; the windows need to be large enough and low enough to escape from. Opening windows should be at least 50mm x 450mm and at least 0.33m² in area. Rooflights must be between 800mm and 1100mm from the floor.

If the loft extension transforms a two-storey home into a three-storey home, then further measures need to be put in place to adhere to fire safety requirements:

  • Escape windows that are over 4500mm from floor level are not classed as safe fire escape routes and therefore Building Regulations require an enclosed staircase that provides fire protection leading all the way down to an exterior door.
  • Staircases that rise from a room (instead of a hallway) can either be entirely enclosed until reaching a door at the end, or a staircase can be enclosed at the base of the stairs where there is a lobby. This lobby is required to have two escape routes, at the front and back. The lobby walls have to be fire-resistant.
  • The loft room will also need to be protected by fire doors.

The doors used on the staircase to and from the loft extension needs to be fire resistant, they can be glazed as long as the glazing is fire resistant glazing.

If you have any questions and concerns about the building regulations and specification of glass to your loft conversion project, please contact the team at IQ Glass.