It’s one of the most popular extensions to do on a home and is estimated to add between 10% and 20% in value, but what are the tips and watch-out-fors you need to be aware of before embarking on a basement conversion?
We asked five experts — from lighting to colour schemes, here's what you need to know if you’re planning to convert your cellar.
DON’T think you need to have a cellar to do a cellar conversion
It might come as a surprise to find out that you don’t need an existing cellar to do a cellar conversion.
“Most cellars that already exist were not designed to be living spaces — they are often not insulated and don't offer adequate head height to be seen as habitable spaces,” says Charlie Avara of All Done Design.
“Whether a property has an existing space below ground or not, you are likely to still have to go through the process of excavation, reinforcement and insulation to achieve a usable space.”
What’s actually more important is if the ground conditions around your home are suitable for this type of conversion.
“This is because it needs digging out without compromising the structure of your home and surrounding buildings,” says Natalie Mitchell, property and construction expert at Homehow.co.uk.
That said having a cellar already — even if it’s just a crawl space — makes doing a conversion much cheaper, as it’s less likely that the foundations will need to be adjusted, which adds time and money.
DO consider what its function will be
Obvious as it may seem, you need to think about what you will use your cellar conversion for.
“It’s crucial that there is a specific function for the basement — whether it’s a spare bedroom, additional bathroom, or another living space — so that prospective buyers feel like there is a need for the space and that it’s not just an empty room with no purpose,” says Simon Bath, a creator of Moveable.
Not having a clear sense of the purpose from the start of the project can also lead to complications later. Avara cites the addition of a bathroom, utility room or kitchen where “the drainage for the wastewater needs to be in position before the concrete floor is installed. This is a consideration that can trip people up”.
DON’T skimp on waterproofing
If there’s one thing you don’t want from your cellar, it’s damp.
“If your new basement isn't waterproofed properly, water will seep through the walls and into your finished space. This can cause mould and other damage that could have been avoided with proper waterproofing techniques,” says interior designer Linda Haase.
A specialist cellar expert will always pay proper attention to waterproofing but it’s worth checking just in case.
DO think about what will add value
If part of the motivation behind doing a cellar conversion is to add value when selling on then speak to local estate agents about the best use of space, and if there is a ceiling price for the properties in your street.
“If you live in an area that’s popular with families and young professionals, it may be worth adding the space and going for a high-end finish to make it desirable to the market,” says Mitchell.
“However, if the cost of the work exceeds what someone is willing to pay for that extra space, you won’t add value.”
Using the space for a home cinema or swimming pool will cost more but will add the most value if this is something that people want in your area. Usually adding a guest suite, utility room, playroom or extra bathroom is also a sensible use of space.
DO know lighting is crucial
How you light your cellar will make all the difference. If it’s dark and feels like you’re underground, it’s not going to be a space you want to spend time in.
To avoid this, make the most of any natural light you do have, by creating light wells around the sides to bring in as much light as possible.
“If the basement is going to extend out longer than the property above, you could consider lighting from above. You could think about a frosted or glazed ceiling in some parts of the basement,” says Sahar Saffari, interior designer at Hi-Spec Design.
“You can also include mirrors or glassed furniture in the space to reflect the light around the space.”
If natural light is minimal, Mitchell suggests you “use bulbs that are bright but not stark. Wide beam lighting with LEDs that mimic natural light will help it to feel bright and airy”.
Haase suggests using recessed lighting as it doesn’t take up space or cause a glare on the walls. “Recessed lighting also allows you to use dimmer switches so that you can adjust the brightness depending on your needs and mood. If you're looking for a more dramatic look, chandeliers can be installed in the ceiling above the stairs leading down into the basement.”
DO give plenty of thought to the colour scheme
While it’s sensible to plan ahead with most elements of a cellar conversion, the colour scheme is something you should wait on.
“It’s a good idea to leave the decorating until last, so you can see how paint colour samples look and feel under the artificial lighting,” says Mitchell.
“Bright whites and light greys and blues can increase the sense of space, while mid-to-dark greens can make it feel warmer and more natural.”
Bath thinks you need to play it safe if you’re planning to sell the property on: “Colours such as green, bright yellow, dark brown and black can sometimes be classified as a no-go zone if you’re looking to boost the value of your property.
“Sometimes smaller accents of black could help with achieving a desired dramatic affect. However, minimalistic colours are likely to be more palatable for prospective homebuyers.”
DON’T underestimate how big a project it is
Our experts all agreed that getting a cellar conversion is a major project that needs specialist contractors.
“From the cost, time, effort, planning permissions, and disruption to the property to choosing the labourers, and the upkeep, there is a lot to think about and it shouldn’t be a rushed decision,” says Saffari.
“Get a variety of different experts to provide recommendations and costs to make sure that you have a well-rounded view of the potential outcome of the project and minimise any problems that may come unexpectedly later down the line.”