Building on a Sloped Site

If you’ve fallen in love with a sloped or hilly site, you may be torn between the amazing benefits of fantastic views and the stress of trying to figure out whether the added complexity is going to result in cost overruns and operational headaches. Hillside homes are nothing new; the houses in the town of Modica in Sicily are built on steep inclines, nestled together and punctuated by tiny alleyways. Across the Himalayas, gravity-defying stone and timber houses seem to emerge from the faces of the mountainside, while Alpine cabins are built from the very trees that grow in the hillside forests and perch at the edge of steep drops.

If you’ve chosen a hillside location for your new home, chances are that it’s the amazing views that have drawn you to it. It’s that strong visual connection to the greater surroundings, whether urban or rural, that ground us psychologically in our homes. The beauty of a breath-taking view can inspire the deepest parts of us, and also speaks to a basic animalistic need for safety – from a high vantage point, we have an overview of what lies beyond; we can see danger coming from far away. Furthermore, a wide aspect view enhances our experience of weather and changing skies, rooting us more deeply in nature, which in turn brings greater well-being.

In recent times, hillside sites have brought about some of the most inspiring innovations in home architecture. The challenges of access and the creation of strong foundations have led to some of the most dramatic and beautiful homes across the world. The approach to building on a slope can be either additive or subtractive. Additive buildings perch themselves on top of steep gradients or even cliffs, often leaving a minimal footprint on the ground, with the most jaw-dropping examples often appearing to float above the landscape.

In recent times, hillside sites have brought about some of the most inspiring innovations in home architecture. The challenges of access and the creation of strong foundations have led to some of the most dramatic and beautiful homes across the world. The approach to building on a slope can be either additive or subtractive. Additive buildings perch themselves on top of steep gradients or even cliffs, often leaving a minimal footprint on the ground, with the most jaw-dropping examples often appearing to float above the landscape.

In terms of what direction your new home should be oriented, it doesn’t always work out as easily as it did for the owners of Highway House. It often happens that the most incredible view is in a completely different direction to the most optimal orientation for maximizing sunlight. If you’re in the Northern Hemisphere, you might have a stunning view to the north-east, but direct sunlight obviously comes from the south. Long narrow plans can be a great solution, allowing you to have many rooms with double aspects, that is, windows on two sides: one side for views, the other for light. Huge walls of glass can be really dramatic in terms of the experience of a view, but can be a huge drain on energy, resulting in great heat losses if they’re orientated in the wrong direction.

A fantastic solution to this is the very careful placement of picture windows, which can frame a spectacular view like a piece of art, and celebrate it in a different way to the showy panorama. London architect John Pawson is the king of the picture window, designing windows that draw the eye to admire a view in a more subtle than dramatic way. The exclusion of window frames or mullions is key to the effect.

A further amazing benefit of a hilly site is privacy; you’re going to get at least one aspect of your house that is not overlooked by neighbors, so make sure that you make the most of this. Plan your home so that the areas in which you’d like more privacy are facing outward. Sunbathing with a view, anyone? Similarly, a modest entrance to a hillside home can be played off against the dramatic experience of a drop to the rear, as designed beautifully in the Goulding summer house, which cantilevers impressively over a rocky stream, appearing to elegantly float.

A common approach to designing for hilly sites is a little more modest than the dramatic gravity-defying house on stilts, and lies midway between additive and subtractive, utilising a little of each. This house by Swedish Architects WRB sits on a sloped rocky outcrop overlooking a lake. Part of the building is sunk into the landscape, ‘subtracting’ from the hillside, while the form protrudes beyond the lines of the ground, and the ‘additive’ living spaces on the higher floor appear to float above the lake.

There are numerous other examples of split-level homes that comprise a series of block forms or planes that step and overlap along the undulating forms of the landscape. With their backs nestled into the undulating ground plane, these homes are protected against the elements from behind. It’s important to work out where the prevailing winds come from on your site, and if you’re lucky, the natural features of the site will provide protection. If your site is very exposed, clever design of the house itself can help provide this extra shelter. Again, what’s crucial is the balancing act of maximizing views, optimizing solar gain (or shade), and ensuring that there’s good access from public roads and for services.

The V House in Colombia, designed by Plan B & Mazzanti Architects, has a driveway that comes off the main road, to create a parking area at the roof level of the main house, which leads on to stepped roof terraces that provide a view across a vast landscape.

The V House also maximizes the three dimensional internal volume of the space, which comes from having a multi-level house. Dramatic and interesting spaces are created when the section of the building is well considered in the design.

Finally, let’s talk about the subtractive, which describes houses that are cut into the landscape. They sit within hillsides, hidden by the slope, becoming enveloped by the landscape. Such homes are private, have a small ecological footprint, and use less building material, but optimizing sunlight entering the whole house may prove difficult for homes with larger floor areas. Choosing a site with the correct orientation is vital.

To finish, here are OPOPLAN‘s 7 Top Tips for building on sloped sites:

1. Decide whether a home that is additive, subtractive, or somewhere in between is the best approach for your site.

2. Work out whether the best views are also in the direction of the sun, and if not, consider cleverly framing views over large expanses of glass.

3. Consider prevailing winds and take advantage of natural features for protection.

4. Be careful about drainage on your site – water that flows down hillsides needs to be diverted away from your home.

5. Access can be tricky, and can even be dangerous if using a steep driveway in bad weather. In locations where you may have ice or snow, you may want to consider heating your driveway.

6. Seek professional help on costing your project. Costs of building on sloped sites can certainly be higher, because of more complex access for contractors, excavation & filling, drainage, and increased structural elements such as steel stilts. However, many costs can be offset by lower land prices on hilly sites.

7. Expect the unexpected when building foundations, and make sure you have a good contingency fund. It’s hard to know with a sloped site when you will hit rock, and it may require excavation which can be pricey. One your foundations are in though, hopefully the only remaining surprise will be just how spectacular that sunset view from your living room really is.

And remember, OPOPLAN’s awesome unique software can gather even the most complex site information and create the best designs for every site.