Subterranean basements

Need more space - but want to still keep your garden space for those balmy evenings? Why not invest in a subterranean basement which adds space and value to your home? 

An almost invisible basement with the garden kept intact

An almost invisible basement with the garden kept intact

As we have just recently been granted permission for a large basement structure under a rear garden in Holland Park, we thought it would be good to talk about the design and planning aspects of such a basement. 

First decide what you want the space for, this will dictate the size and volume you need. Of course basements can be flexible spaces and do more than one thing but this means the space has to be quite large to accommodate ‘what could be’ rather than ‘what is’. As the process of planning, designing and building is quite lengthy and laborious you should maximise the space you can get (the volume /sqm will be stipulated by your local planning authority and may depend on how big/extended your home is now). 

Place rooflights where you can to encourage light into the volume.

Place rooflights where you can to encourage light into the volume.

In creating a layout you should consider adding rooflights throughout the ceilings to help natural light to enter the space, try to place them on different faces to get sunlight throughout the day as well as daylight. Having a lightwell can also be beneficial to gain not just light and ventilation but to understand how the outside conditions are and to keep track of the day. 

A lightwell to allow more connection with the outside, it is also a nice opportunity to make a small garden!

A lightwell to allow more connection with the outside, it is also a nice opportunity to make a small garden!

Shaping the space can be an effective way to get away from that basement ‘underground feeling’ with a curved or undulating ceiling which can work well to enhance a view, a light path or simply just look beautiful. 

Curved edged ceilings allow an easier passage for natural light to enter the space from rooflights

Curved edged ceilings allow an easier passage for natural light to enter the space from rooflights

Even paper lanterns can make a fun ceiling and give a beautiful filtered warm light in the space

Even paper lanterns can make a fun ceiling and give a beautiful filtered warm light in the space

Lighting is always important and never so much so as in a basement space. Introduce warm, glowing, welcoming lighting which is mainly upcast rather than downcast to make the space feel taller and enhance the overall volume. 

Take into consideration that you will need a planning application for any new basement /excavation works. Council boroughs differ in their approach to basement planning applications, however be prepared to pay upfront for reports, namely a tree survey, soil report, structural engineer drawings and calculations, noise and dust report, traffic management report to name but a few, but once validated the planning department will take approximately 6-8 weeks to respond. Party walls will most likely be required too which will take around 2 months. Construction can begin once all planning conditions have been discharged by the local council.  

Construction times and costs vary greatly depending on the volume and scale of the basement, but if you already know your budget then the basement can be sized accordingly to fit this.

Basements can be decorated in a number of ways but it is best to invest in finishing materials that give depth, can reflect the natural light and warm the space. Furniture too has to be thought about , in flexible spaces loose furniture has to be movable (for adults and children if the area is to be a playroom) and have more than one function , ie cushions which can be made into beds and then changed to low seating, from entertaining to socialising.  The basement should have plenty of storage in the structure as it is unlikely you will want to be moving furniture up and down stairs from the main house and back. 

In London, it may be one of the biggest spaces so just enjoy an open space for what it is.

if you are thinking of adding a new subterranean basement to your home - We have years of experience in basement planning, design and construction, so why not give us a call?