What should be considered when purchasing sloped land?

Today we present a new article focused on a highly practical and useful topic, especially for those of you evaluating land for construction. We are referring to the possibility of purchasing sloped or flat land, or even for those who already own a plot and have decided to start 2018 with a housing project.

The truth is that many plots suitable for construction are available on the market, but challenges may arise when we decide to purchase sloped land, as they often appear more economical at first glance compared to flat plots.

It is true that, generally, flat land is more convenient and economical in terms of budget and project scope; however, today we have sufficient technical resources to level land through earthworks and retaining walls.

In today’s article, we will evaluate the advantages and disadvantages of purchasing sloped land, as well as propose strategies to help us make the most of the terrain’s conditions to reduce construction costs and improve the sustainability and comfort of the home.

We must understand that due to its morphology and requirements, building a house on sloped land increases the cost of earthworks, along with their corresponding retaining walls, and in certain cases, it may even increase the cost of the foundation.

First and foremost, we always recommend contacting an architect before purchasing sloped land. You may contact our studio; we offer free advice during the search and purchase phase, as it is important to us that you reach the project phase with land in a condition that ensures the project’s viability, especially when it comes to purchasing sloped land.

Advantages and disadvantages of purchasing sloped land

At first glance, one might say that the decision to purchase sloped land will entail more disadvantages than advantages. However, in reality, this is not the case, as we can employ many strategies to use the slope of the land to our advantage.

Orientation of the slope

Firstly, it is necessary to evaluate the orientation of the slope of the land we wish to purchase.

Ideally, it should be south-facing; however, if it is oriented towards the north or another direction, we must use other construction strategies to settle the house and take advantage of the limited solar incidence available.

But let us delve a little deeper;

As previously mentioned, a south-facing orientation is the best we can find when purchasing sloped land. In these cases, we have the option to capture maximum light and solar energy by placing a large facade with wide openings in this orientation.

To increase solar gain, we can use the slope itself by building the house on different levels, thereby multiplying the facades to expand the south-facing capture surface.

If, on the contrary, the chosen land has other orientations, we have many architectural options to design a house that is just as efficient and comfortable as one on south-facing land. For this, the incorporation of interior courtyards into the design is very important, allowing us to capture southern light, especially in winter.

Skylights are also elements to consider, as besides illuminating interior parts of the home, they increase the capture of light and solar heat.

Water risk (runoff)

It may seem obvious, but it remains vital to mention that sloped land suffers from erosion and damage when it rains, as water naturally flows down inclined terrain.

It is very important to keep in mind that, although purchasing sloped land ensures that water runoff will occur naturally, we must be cautious and verify that water drains correctly during heavy rains. Making a good provision for water collection and channeling elements can save us many problems and concerns in the future.

Urban planning regulations

This point applies to any type of land: when deciding to purchase a plot, it is important to know the current urban planning regulations, as their limitations will condition the design and occupancy we can achieve on the plot.

In fact, contradictions sometimes arise between the project and regulations; for instance, a multi-level implementation may be proposed that exceeds the maximum permitted height, or we might place the construction in a less sloped area to facilitate the work, while regulations require the facade to be aligned with the street.

These are examples of possible situations that can be avoided with thorough knowledge and by always consulting with experts in case of any doubt.

Views

Normally, when purchasing sloped land, we ensure good views of the surroundings.

However, there may be elements that obstruct the views, such as antennas or high-voltage lines, as well as trees or unevenness in the terrain itself that prevent good radiation at certain times of the day. But if we know our land well, we can consciously locate the windows of our project to frame what interests us.

Furthermore, we can always turn our back on the surroundings if they are not very pleasant, using landscaping for interior courtyards to turn them into pleasant and climatically functional spaces.

Knowing the land well

With these preliminary concepts in mind, let us address one of the most important topics to consider when preparing to purchase sloped land.

It is very important to understand the morphology of the land and conduct a geological study to know the type of subsoil we have, as depending on the type of terrain, we can utilize one location and foundation strategy or another.

Starting with the foundation, when purchasing sloped land, we are usually limited to two strategies: on one hand, we can choose not to modify the natural slope of the land and simply anchor the house using deep piles in the ground.

Although this is a common strategy, in ecological terms it is not the most recommended alternative, as the final result remains completely isolated from the natural terrain, wasting many of the advantages it can offer us.

That said, this typology is recommended for cases of land with steep slopes where connection to the natural terrain is impossible, as well as in poorly cohesive soils where the extra costs of foundation for adaptation to the terrain could skyrocket.

Secondly, we have the option to work with the morphology of the land itself and adapt it to our needs through earthworks and soil retention systems. In this way, we can integrate the home into the terrain, thus taking advantage of the thermal inertia of the earth itself.

In these cases, the foundation ends up being very similar to what we might find on flat land and will depend on the type of subsoil. To know if the land is firm enough to safely perform earthworks and soil retention, it is highly advisable, if not mandatory, to commission a geotechnical study or preliminary test pits to check the firmness of our land before purchasing it.

In the case of land with medium resistance, the most recommended approach once again will be a house that adapts to the slope, so that we distribute the loads and reduce the need for soil retention and foundations.

Finally, in the case of soft sloped land, the recommendation will likely be not to purchase the land; however, if we already own it, the solution probably involves concentrating the weight of the house on a foundation slab or on deep piles, depending on the case and the complexity of the subsoil.

Normally, a complete geotechnical study costs around 1,000 euros, but it is an investment we fully recommend as it will save us many unforeseen events and extra expenses during the construction process.

As a more economical alternative, we can also perform several test pits at different points on the land, which costs about 200-300 euros and provides basic information on the type and depth of the resistant layer. This allows for a purchase decision with more information.

On some occasions, an agreement can be established between the owner and the buyer to decide who bears the costs of the study, always knowing that the owner is not obliged to provide it for the sale.

Harness the Ground

Let us now address one of the most interesting points of the article. This involves reviewing those strategies we can use to take advantage of the morphology and characteristics of the land, organizing it to our benefit to achieve a project that thoroughly optimizes the supposed “disadvantage” of purchasing sloped land upon which we intend to build.

Using the slope of the land available to us, we can consider working with it either through a system of terraces upon which we will build our house, or by burying the home completely or partially.

In the first case, the natural slope of the land is modified to generate a series of flat surfaces on which we can work comfortably. Subsequently, the house grows in height along these platforms, and we must, from the design phase, distribute the interior program orderly, taking into account how the main access—pedestrian and vehicular—to the house occurs, and separating wet areas, bedrooms, and day and night rooms.

This system is inspired by methods traditionally used in the countryside. When a crop was located on a sloped hillside, to work comfortably, farmers began to generate flat surfaces supported by retaining walls made from local stones. We can find landscapes of this type in many places around the planet, and it is a safe bet as its utility and effectiveness are ensured by its persistence over time.

The other alternative also has its basis in tradition. Burying a home takes us back to the origins of civilization, when the shelter of the earth was sought to maintain heat thanks to the inertia of the terrain and its constant temperature throughout the seasons.

Therefore, we have the option to bury our house completely or partially, creating interior spaces that are thermally insulated and sheltered from the elements. This does not mean they have to be dark and damp spaces; by using skylights and natural ventilation systems, we can achieve very comfortable and pleasant rooms.

Working with a team of architects who understand these strategies and know how to apply them according to our needs is something we fully recommend, as it is the best way to ensure a good final result.

Another aspect we must value when purchasing sloped land is, quite simply, the existing vegetation on the land where we are going to build. It is interesting to incorporate the trees and some of the plants existing on the plot into the project, turning them into places of shelter and shade for the home. Furthermore, some city councils do not allow the indiscriminate felling of certain species and will require us to keep them in place or transplant them.

Communicating with the city council and staying up to date with the current regulations affecting the land in question is vital to avoid later surprises. The entity will also inform us about the frequency of precipitation in the form of rain or snow in the area, aspects that may hinder road access to the home, as well as current public services and urban development.

Designing a house on sloped land

Finally, when we want to purchase sloped land, we must also anticipate more practical issues regarding the construction plans and design of the future house.

For this, it is vital to start by evaluating the layout and orientation of the plot itself. Identifying the best access point is recommended, establishing access from the street either at the top or bottom of the land.

Next, check the orientation of the slope and the surroundings. That is, the views, buildings, or vegetation that may prevent solar radiation, what type of vegetation exists in the area, climate, etc.

Based on this data, we can begin to consider which location strategies are most pertinent, how we will manage the privacy of the home and its relationship with the street and the surroundings, and above all, what energy capture and production systems we will use.

In broad terms, the most viable interior distribution is one that places the day rooms (living room, lounge, dining room, and even the kitchen) at the lowest part of the slope. If we build on two levels, these would be on the ground floor, in direct relation to the exterior access and connected—if possible—to the garden to allow for opening to the outside on sunny days and in summer, using porches, pergolas, or terraces.

Incorporating courtyards into the design of a house on sloped land

Another strategy to consider when proposing options for our house on sloped land is the incorporation of courtyards into its design. This alternative is very useful, especially in cases where the slope is not south-facing. Through courtyards, we manage to bypass the orientation by creating four new facades that capture light and introduce it into the home, and consequently also capture solar radiation.

In temperate climates, courtyards also function as ventilation elements but with controlled temperatures that help to climatize the house.

Access to a house on sloped land

Lastly, and no less importantly, it is logical to think that on sloped land we must take into account the vertical movements that will occur.

When purchasing sloped land, we will certainly generate different levels for access, the home, and the garden, which we must relate by incorporating stairs or other architectural elements. It is important, as well as mandatory, to guarantee accessibility to the basic rooms of the kitchen, bedroom, and at least one bathroom for a person with mobility issues, which, although a wheelchair always comes to mind, could also be an elderly person or someone who is temporarily injured.

In fact, daily activities can benefit from a good project that works with routes consciously to facilitate the day-to-day life of the people who will live there. Encountering stairs when carrying shopping bags or strollers, for example, is something we can avoid with good foresight and distribution of rooms.