Cantilever design
Don’t be left hanging in the balance as to whether a cantilever design is right for your project. Sabatino Torchitti from Resi does the homework for you
Are you guilty of spending your time buried in swish architectural magazines, ogling fancy designs from around the world? Then you might have encountered this month’s special feature: cantilever design. This gravity-defying detail was first seen in the civil construction industry, appearing in bridges such as the Forth Bridge in Scotland. However, in recent years, ambitious homeowners and architects have been bringing cantilever features into the residential sector, delivering some surprising benefits for those lucky enough to have them.
WHAT IS A CANTILEVERED STRUCTURE?
Cantilever design is defined as a structural feature that extends horizontally from a vertical element and is only supported at one end. This can be as simple as a cantilever balcony or an open corner of a building. It’s also a popular design for recycled shipping container new builds, where one unit juts out from the top of the other.
Don’t be fooled, there’s more to cantilever design than just stunning aesthetics. On a practical level, having a suspended element allows you to create a larger home without
eating into your garden. Perhaps the most beautiful example of this is Frank Lloyd Wright’s famous Fallingwater House, with its terraces suspended over the babbling brooks and a waterfall. Most of us don’t have such a dramatic water feature, but the principle is the same.what’s more, the shaded alcoves that result beneath help to reduce solar gain in downstairs living spaces and create privacy.
A cantilever design can also help circumvent certain planning hurdles, for example by allowing ground floor access points to be retained or preventing protected trees from getting the chop. Of course, being so eye-catching, cantilever designs come with their own planning challenges, so they mainly pay off in the hands of experienced designers who can manage the planning process on your behalf.
GETTING THE DETAILS RIGHT
When designing cantilevered structures, you and your architect will need to balance what’s possible from a planning perspective against the amount of space you want to create. How far your design will be able to protrude will depend on construction. Don’t forget: a balcony is a cantilevered structure, albeit a very small one. You don’t always have to opt for big and bold.
If you’re set on going all-in and want to know the maximum span, there are three main areas your designer will need to consider:
● The load above — how much weight is on top of the supported section of the structure?
● The anchor point — how is the cantilevered structure connected to the other elements of the building?
● The materials you plan to use and their weight and strength.
As there’s so much structural work involved, having a good structural engineer on your project will be vital. It’ll be their job to make the structural calculations that will allow your builder to create a safe and legal final result. These structural details will be checked by building control to make sure your project is compliant with the Building Regulations.
CONSIDER THE COSTS
As cantilevered structures are more technically ambitious than most other features, you should
be prepared to pay a premium if you want to include them in your design. Not only will an architect and structural engineer likely charge a premium rate to cover the extra attention these designs demand, you’ll also be confronted with an even bigger price tag when it comes time to build. Cantilevered structures are made possible thanks to both steel beams and reinforced concrete, materials which don’t come cheap. Therefore, if your biggest priority is to keep things cost-efficient, this might not be the design for you.
Of course, you might find that the space a cantilevered design offers you is justified by the planning hurdles it helps you overcome. There’s the resale value to consider too; a well-made cantilevered design is a luxurious feature that could deliver a high-end price for your home. However, if you are looking to make a return on your investment, we recommend researching your local housing market first. Some areas suffer from a ceiling price, meaning no matter how nice your development, your home won’t exceed a certain price point on the market.
If you’re still on the fence, consider consulting an architect about what is and isn’t possible. Unlike cantilevers, these professionals won’t leave you hanging (though they may make terrible design puns).