A popular building addition especially in London

Side infill extensions are a popular building addition, particularly in London properties where space is a premium. By extending to the seldom used, redundant passages down the side of traditional terrace homes, you can dramatically increase the liveable internal space to a home by extending to the side with a relatively small addition that will significantly enhance space and natural light with maximum impact.

Small glazed sidefill extensions to a home, often replace common storage spaces that hinder the useable space of the dwelling. Reconfiguring the space by adding a small glazed sidefill extension, maximum light spills through to both the new addition as well as the original space helping to create a welcoming and airy space that offers flexibility.  

Slim framed sliding glass doors, such as Keller minimal windows®, are a popular design choice. With minimal framing and large glass sizes available you can allow as much natural light as possible to enter the internal living areas through to the rear elevation drastically reducing the need to use power to switch on the lights during the daytime.

Side infill extensions often have a glazed roof for this same reason, allowing light to enter the interior of the home throughout the day. Where the Keller minimal windows® and glass roof meet a small steel support will be required. IQ Glass will be able to detail and design this steel support to ensure the required support is given whilst making the steel section as minimal as possible.


Planning permission and structural work needed.

Major tasks often required for this kind of extension include:

  • On the kitchen side of the line dividing your property from that of your neighbour, construct a new wall. It will be necessary to confer with the owner of your neighbouring estate. It may be necessary to install the wall only on your side.
  • Give the additional area a new roof. To make their kitchens brighter, many opt for skylights or totally transparent roofs.
  • Break through the present back room's side wall.
  • To blend the new enlarged space with the previous one, install a new floor.

Since 2008, council regulations governing projects of this nature have been modified, therefore as of 2017 planning permission is no longer necessary. This is applicable provided that the addition is limited to the ground level and doesn't rise higher than four metres.

Additionally, before construction begins, it cannot be wider than half the width of your house. It's important to keep in mind that there will probably be building requirements you must follow even though you won't need planning clearance.



Door Configurations for side infill extensions

Side infill extensions are often completed with some form of door configuration such as a pocket door, pivot door or sliding door

minimal windows pivot doors are perfect for side infill extensions that desire a modern and unique twist. Pivot doors can be specified to nearly any size and can be colour matched to existing doors in you home. Pivot doors are great for daily usage and are easy to maintain.

If you desire a more minimal and seamless door type then pocket doors are ideal. Pocket doors are often favoured due to the fact that when opened they slide into the building structure and disappear. Pocket doors are used when garden space is limited and something such as a pivot door would minimise that space further when opened.

minimal windows ultra slim sliding doors can be used for a side infill extension if the required space can accommodate them. Sliding doors will open up a vast area which will allow for full indoor to outdoor access. This can be advantageous for larger events and gatherings.

Side infill extension croft road kitchen
Side infill extension claremont interior

Side infill extensions project examples

At minimal windows we have completed a handful of side infill extensions. See below for an array of our completed projects. 

Warwick Gardens

A historic Victorian London home with a glass side infill expansion had Keller minimal windows®, slim framed sliding glass doors installed. Popular building additions include side infill extensions, especially in London where available space is at a premium. The arrangement is improved, the size of the living areas is increased, and the interior is opened up to better accommodate contemporary design trends.

The custom glass addition has a structural glass roof that raises the kitchen/dining area while thoughtfully letting natural light fill the rooms. Even with the sliding glass doors closed, the Keller minimal windows® have a full floor-to-ceiling glass wall that looks out onto the garden thanks to their 21mm vertical framing and frameless surrounding frame finishes.

Side infill extension warwick gardens
Side infill extension warwick gardens doors closed

Claremont Square

The New River Conservation Area's Grade II listed Georgian end-of-terrace house benefited from a brand-new modern side infill extension utilising minimally framed sliding glass doors and a total modern makeover.

For these kinds of projects, frameless structural glass is a popular option because of how little it detracts from the surrounding building. For the side infill expansion, a structural glass roof was chosen.

While allowing main access, the minimally framed sliding glass doors offer an idyllic connect with the graden. The modern extension's views and natural light are maximised by the slender 21mm sightlines.


Side infill extension claremont interior
Side infill extension claremont rain

Croft Road

In order to significantly increase the footprint of usable space, architects Holland Green were chosen to transform the once-useless side alley into a luxurious kitchen space with a glass side infill (or glass side return), levelling the garden lawn, and slim framed glazed kitchen doors that slide open to the patio with flush thresholds.

To optimise natural light throughout the day, the glass side infill extension's design brief called for flush thresholds, slim framed sliding glazed kitchen doors, and seamless transitions to the patio and garden.

If you have any questions regarding extension projects, or require more advice on glazed sidefill extensions, Contact the minimal windows team today. 


Side infill extension croft road exterior

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