Understanding the Challenges of Building on a Sloping Site
Building on a sloping site is both a problem and a gift. The problem is that it adds complexity and therefore cost to the project. The gift; when you’ve finished you’ll have a much more interesting home that sometimes lends itself to views that others won’t get to enjoy. That’s also the beauty of having a private builder design and build you a prestige home.
Do all Home Building Sites Slope Downward?
There are a lot of considerations for building on a sloping site, the first, is the severity and direction of the slope. Some blocks slope toward the street (up slope) and some toward the back (down slope), others from side to side (cross slope). Blocks that slope toward the rear are easier to work with, while those that slope toward the street often need more excavation and retaining walls. This can add to your building costs. Beware that building on a sloping site will cost more than building on a flat block, even if the slope is moderate.
With clever design you can reduce the cost of building a on a sloping site. One of the big expenses of building on a sloping site is excavation. Excessive excavation should always be avoided as it can cause instability and erosion. In addition and can prevent the block from draining properly. The more soil that is excavated the more retaining walls you will need to hold back the remaining soil.
So you have purchased your block and are looking to build or are looking to purchase your dream block but are not sure of the building costs.
Steep sites are classified as difficult sites. They can have a moderate slope 1 – 3 m or a more severe slope of 3m and upwards. Generally the steeper the slope the more complex the design of the home will be and the more it will cost. There are a number of different fall profiles that come with a steep block each of which will have their own characteristics to deal with.
As a rule volume builders will not build on steep blocks. Due to the nature of each block being different all homes will be custom designed. For this reason it is important that you deal with a building designer that is experienced with the requirements of this type of design. Equally important you need to select a builder that also has experience and expertise in this type of construction, even if they are a little more expensive.
Getting a builder involved early in the design process can lead to big savings as they can advise on the most economical way to deal with the structural issues that may arise.
Building on a steep site will give you a unique custom built home which often has spectacular views and very functional floor plans. Always keep in mind that building on sloping sites tend to produce much larger homes than building on a flat block. This is because the fall of the land tends to lend itself to basement construction which can add as much as 80m2 (9 squares) to the house footprint.
The purpose of this guide is to give someone looking to build on a sloping site a simple over view of the reason that such buildings are much more expensive to build than a typical flat block home. In the next few articles we will explore in more detail the different fall profiles and how they can affect the building costs of you home.