Building a New Home on a Sloping Block: Everything you need to know!

Posted February 11, 2020

building on a sloping block

When people think ‘sloping block’ they usually think about the additional costs involved in building a new home on a difficult site.

This is not an unreasonable assumption. When you choose to build a home on a sloping block there are going to be some additional costs involved.

However there are also a whole lot of benefits to building on a sloping block too!

In this article we will run through the most important things that you need to know when considering building on a sloping block, including;

  • Different types of sloping blocks
  • Additional costs
  • Design considerations
  • Choosing the right builder

Sloping Block Types

There are many different types of sloping blocks, but they generally fall into one of the following categories:

  • Sloping up – the low point being at the road
  • Sloping down – the high point being at the road
  • Cross fall – the slope is from right to left or vice versa
  • Cross fall + sloping – a combination of the above

Sloping up blocks often lend themselves to capturing views from the front and create an opportunity to have quite a grand and impressive elevation.

When you build on a block that slopes upwards it makes sense to dig into the site and create an under croft garage and hence have the possibility of a 3 storey appearance at the front of the block (and a 2 storey at the rear).

Of course you can also opt for a 2 storey appearance at the front, reducing to a single storey at the rear as the home transitions to the rear back yard.

Blocks that slope downwards may offer rear views that overlook some interesting geography such as a river, ocean or valley.

However, when compared to a block that slopes upwards, the down sloping block presents a lot more design challenges - with compliance for overlooking neighbours being the main obstacle.

Of course whether your block slopes up, down or from one side to the other, the biggest consideration for design and additional costs will be the severity of the slope.

Steep slopes will create many more design challenges and potential site work costs when compared to a more gentle or gradual slope.

Throw cross fall into the mix and you add further complexity, which usually results in more cost and more difficult design compliance and design functionality considerations.

A general rule to follow is the steeper the block, the more challenges it will present. Remembering, of course, our main consideration is the area of the block on which the house will be built, not the entire block.

Which leads us on to our next topic, costs.

Additional Costs when Building on a Sloping Block

Generally speaking blocks of land that slope upwards from the road will incur more site works cost as there is a lot more cut and fill work required.

These blocks usually require excavating for partial or full under croft garaging and therefore require heavy duty machinery hire and heavily engineered walls.

Site access is also a big cost consideration. The builder will need to roadmap the process for site works and construction to ensure the required machinery and vehicles have access to the site and understand where additional equipment (such as a crane) will be located.

Costs to consider when building on a sloping block include:

  • Cavity filled engineered under croft walls
  • Water proofing of underground walls
  • Retaining walls
  • Brick build up under the house to allow for level floors
  • Additional steps
  • Removal of fencing to allow site access and building on or near boundaries
  • Undermining your neighbours building which will incur engineering costs and stabilisation of soil
  • Split levels inside the home to allow transitioning to natural ground level outside
  • Removal or import of additional fill

A good tip to remember is, if possible, avoid building on the boundaries of your block. This may avoid costs which might include undermining neighbouring structures and fences.

The key to minimising construction costs on a sloping block is to reduce the amount of earthworks required and reduce the amount and extent of engineered retaining walls.

This can be achieved by adopting a house design that suits your block.

Designing a New Home for a Sloping Block

Designing the right home for your sloping block goes hand in hand with selecting the right builder.

Experience is the key here, as is taking an imaginative and flexible approach and finding design solutions that others may overlook.

To get started you should work with the builder to carry out a site inspection and analyse the physical characteristics of the land.

A contour and feature survey at the design stage are highly recommended to help achieve the best design and cost outcomes.

This will allow the designer to get things right. For example driveway gradients must meet strict local council and Australian standards, they cannot be too steep.

As mentioned above, from a purely design point of view, building a home on a sloping block has the huge benefit of allowing you to be much more creative and add more visual interest than homes built on a flat block.

As an example, you can add terracing to break up a steep rise on the block.

house on a slope terrace

building on a slope split levels

Split levels within the home are also a great way to add interest to the design as you follow the rise or fall of the land. Although this adds costs to the design it will help offset site works and retaining costs.

With sloping blocks the opportunity to incorporate higher ceilings can be considered as you work with the land.

Brick build-up under the home with steps inside and outside the home is another design option and can help avoid disrupting the structural integrity of neighbouring properties.

A lot of sloping blocks offer views giving the designer the opportunity to be creative. Adding in balconies and/or bridges and large scale windows which integrate into the living areas will help maximise the outlook from these key areas of the home.

building on a slope balconies and bridges

 

building on a slope bridge design

To see all the photos from this home in North Beach click here

Other design issues to consider are height restrictions, engineering, overshadowing, drainage, maintenance, overlooking, services access and run ins to the home.

We also recommend talking with your builder about achieving a passive solar design to keep your energy costs down for heating and cooling the home. Outline the design concept that you want to achieve and then have them step you through some key considerations, such as the best viewpoints on the block, solar orientation and prevailing winds.

Choosing the Right Builder

If you have purchased, or are considering purchasing, your dream block of land which has a rise or fall from the road - or a cross fall - you need to talk to a builder who is experienced with building on this type of land.

Sloping blocks will almost certainly require a unique custom designed home be created. Rarely will a standard range, off-the-plan design suffice. So make sure the builder has designers on staff who understand the challenges of building on difficult blocks and are experienced in achieving the most economical design outcome to suit your needs.

Engaging a builder with their own design team can also lead to big savings.  They can advise on the most economical way to handle structural issues and design efficiency, while still achieving the home that you desire.

At Novus, we have been building custom homes on sloping blocks across Perth for over 25 years and can offer you valuable advice to help you achieve the home of your dreams.

To find out more, contact us here or call (08) 9240 8001.