The ups and downs of a sloping block for building
All you need to know about building on a sloping block
For many people, building on a sloping block can be an uphill battle, if you’ll excuse the pun.
It doesn’t need to be a battle. In fact, a sloping block will typically have some features that make it possible to build an incredibly interesting and unique home. That is not to say that a sloping block will not have challenges. It will, but it’s a little like the old saying, when life gives you lemons make lemonade. Let’s go through the major points to think about.
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Access to the site is a big factor when building on a sloping block
One of the biggest factors that builders consider, but clients rarely do, is the overall question of access to the site. A level site with access from all sides is a builder’s dream. However, sites like that pretty much only ever exist in dreams.
Most sites will have access constraints of some kind. For example, a site may not be square, it may be triangular, and access might only be possible through a narrow entry at one corner.
The reason access is important for builders is that it influences the speed and ease by which materials can be taken from and bought onto the site. This has a knock-on influence on the time different trades are going to need to do their work, how many can have access at any given time, and what constraints are then put on the type of equipment that can be used on the site.
For example, if you can’t get a good size digger and dump truck in, then any excavation might have to be done with handheld equipment and wheelbarrows, which is much more time consuming and labour intensive. This will be felt in terms of time and cost.
So, access generally, and sloping sites especially, need careful consideration in terms of how building work is going to be undertaken.
Building on a Sloping Block:
Modern design makes a big difference
Historically sloping blocks have been considered difficult to build on. However, a lot of that has had to do with perspective. Yes, they are difficult, in the sense that you can’t just put a cookie-cutter McMansion on them.
Sloping blocks become much less difficult if your builder has some serious design capability and has the construction know-how to make the most of everything the site does have to offer.
Often people choose to build on a sloping block because of its location, usually that it offers a great view, or it is nestled on the side of a secluded valley and drops into a reserve or forest.
So, for example, a split-level or even multi-level home can be designed to cascade down the slope and into a reserve, exaggerating the separation of different parts of the home as it does so. These homes do not necessarily need to cost a lot more and in fact, can be quite cost-effective.
Additionally, the home might be designed to offer interesting openings to the natural topography of the block, by incorporating features such as private gardens and cantilevered decks.
So, if you have found a block that has the views, natural light, or airflow that you want, don’t necessarily be put off by the sloping block. Rather, approach it as a design opportunity to do something unique, put your signature on it.
Design costs shouldn't be out of the equation of sloping block designs
Not all the extra costs of building on a sloping block can be avoided, but there are two general principles that your design needs to take into account.
First, earthworks are expensive, so your design should be such that only limited excavating and earth moving is required.
Next, is the cost of building retaining walls. They are not just adding cost, but they are often rendering parts of the site useless. So, be sure to raise these points with your designer or builder if they don’t raise them first.
Building on a Sloping Block:
Practicalities to keep in mind
There are a number of factors about a sloping or difficult block that need to be understood and thought through.
Starting with the slope itself, the severity of the gradient and the direction it generally takes are most important.
An easy and reliable rule of thumb is that a slope that has an incline of less than two metres of fall is relatively easier to build on. By contrast, a slope that has more than two metres incline starts to demand superior design skill and is likely to increase the overall cost of building.
Related to the above, is the consideration of the site’s topography and contours. If the site does have an incline greater than two metres it is probably a good idea to have a detailed contour survey of the site done by a professional surveyor. This will be extremely useful when it comes to working out such things as the grade of the driveway, where to place retaining walls, and so on.
Another big factor to consider is water. In particular, where is water flowing now, and how the building will alter that flow. It is vital that this be dealt with thoroughly and not left to guesswork, as it can have dire consequences, ranging from problems with soil erosion to a full-on landslide.
Other water-related issues to think through are drainage, damp and ventilation. Good design and planning will accommodate drainage corridors and work to keep water away from the building, without causing other problems downstream, so to speak.
Finally, there is the matter of overall ground conditions. Ground conditions are important on any building site but are especially important on a sloping block. Quite simply, we must be certain of the stability of the land we are about to build on.
We need to know what evidence there is for the height of water tables in the soil, as well as how deep tree roots run, and the actual make-up of the soil. Is it predominately clay or sand? Both can cause plans to be rethought, so best to know early.
For example, if we know that there is a lot of moisture in the soil it can lead to problems of moisture build-up, which, in turn, can cause damp and even put unexpected pressure on the building’s structure. Equally, if there is a lot of rock in the soil, it may mean that excavation of the site may be challenging and more expensive, or it could mean that the house will need to be designed so that it is built out, away from the slope.
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Early, quality advice makes all the difference
There are many builders who don’t like working on sloping or difficult sites, and the truth is they should be avoided. Too many builders are not prepared to apply the design thinking required to take advantage of a sloping block. These builders are use to applying cookie-cutter solutions – with their low-cost, high-margin model – to whatever site a client has. You might be able to get away with that on flat sites with different dimension and aspects, but it will end in tears on a sloping block.
It is a lot to take in, but it can all be managed, provided the team you bring on board know what they’re doing and have a proven track record. So, take your time, do your research, and use specialists as and when necessary. With high-quality advice, you can be confident that a sloping block doesn’t cause you any slip-ups.
If you pick a sloping block, there will be more constraints, and you will need to be a little more creative. Homes on sloping blocks often enjoy many benefits, like better views, and more natural light.
