Land Elevation for Commercial Properties
31 August 2021
Is the Elevation of Your Land a Factor When Designing a Steel Building?
IN BRIEF
- The elevation of the land is an essential factor when designing a steel building on a sloping site.
- Assessing the site’s elevation with a proper on-site survey is crucial to identify any issues with drainage and erosion.
- Building on a slope may cost more due to the need for excavation, site levelling, cut and fill, and specialised foundation work.
- Steelcorp’s expert engineering partners will ensure the correct structural components are used to create a durable structure on sloping terrain.
Elevation, Slope and Terrain
There can be a lot to take in when considering the design of your new structure. Along with designs, pricing, materials and which builder to choose, you also have to work within the natural constraints of your site.
Whilst some sites start off almost perfectly level, it’s more common that your site will have some degree of gradient that needs to be completely levelled out before construction can start. Obviously, the flatter the better – but we can work with a wide range of gradients to help you get your ideal structure. Steelcorp doesn’t get involved in the site works so getting your site level is something to ensure you’ve got sorted before any construction can begin.
To make things easier, we have included a few things you need to know before you begin building a shed on sloping ground, such as:
- Proper assessment of the site
- Potential costs for extra levelling work
- Drainage and erosion concerns on slopes
- Excavation and cut & fill
- Preparing and pouring a stable hardstand base
- How steep is too steep?
Sloping Sites: How to Get The Best Result
Assessing Elevation
An on-site consultation is critical when designing any building, particularly when your structure is going to be constructed on a slope. Getting a proper initial assessment will give you a heads-up for any additional challenges posed by your site so that you and your builder can work through how to overcome them.
If you don’t carry out a site analysis before beginning the design process, you could be faced with a multitude of issues from flooding, to structural issues, to additional construction costs you may not have planned for.
When our structure consultants conduct a complimentary on-site discovery session, they will do an initial brief site analysis, however, more precise measurements and surveying work may need to be done for sloping blocks.
A site survey can identify any potentially costly issues that might need to be taken into consideration when you build. These include things like the degree and direction of the slope, natural drainage corridors, potential for slippage or erosion, plumbing considerations and more. It also provides accurate site measurements to make the design stage easier.
Additional Costs for Extra Levelling Work
Here’s the news you may not want to hear: sloped sites that need to be substantially levelled can often incur additional costs.
The nature of a slope can make building more problematic and therefore more costly than building on a flat site. This is because more work is required to excavate the area and cut and fill ready for pouring the slab, so this can take longer and cost more than projects on flat sites.
Drainage and Erosion Concerns on Slopes
Understanding the natural water flow through your property will help you orient your structure in the most ideal position. Regardless of whether your site slopes from front to back or one side to the other, it will likely affect the location and type of drainage required.
Understanding the topography of your block is something that is revealed in the site assessment process, which in turn will allow our designers to locate downpipes and plumbing in the best position.
Excavation and Cut & Fill
Cut and fill simply means cutting away some of the soil on the higher side of the slope and shifting it to the lower side, effectively levelling out the area.
This prep work is very important for containing erosion and for adequate site drainage. Even on flatter sites, the area often needs a site scrape, and if it’s out of level, a cut and fill is the most cost-effective option.
Consider this from an engineering point of view: the more fill on a site, the more is required in the foundations as the piers must be embedded in the natural ground. However, from a drainage point of view you want the structure to be as close to the highest point as possible. Either way, working with a sloping site is a challenge.
What Kind of Base Preparation Do I Need?
Steelcorp provides the engineering design for you, which means that a soil test needs to be carried out so there are no surprises down the track.
A soil test will uncover whether the soil is problematic, which could potentially cause your structure to shift, leading to misaligned joins, doors that don’t close properly, a weakened overall structure or even the slab cracking. If the design isn’t done specifically taking into account the nature of the soil, it could seriously reduce the lifespan of your structure.
This is why prior preparation is so important.
Ideally, a prepared site needs a firm rock base for hardstand when operating machinery and vehicles when working on site. If you have a soil type that’s difficult to work with, additional rock and compaction may be required and sometimes the engineer requires a compaction test to be carried out if there is any doubt about the soil.
For customers looking to position their structure on a greenfield site, a concrete base is usually required for fully enclosed sheds. Be aware that a site that looks flat is often not actually level, and a precision-levelled site is a requirement for pouring concrete foundations. This ensures the formwork can be set and the steel fixed accurately, so the concrete pour sets completely level.
Getting the initial preparation right is the key to a structurally sound and long-lasting structure with a nice level floor.
How Steep is Too Steep?
We’ve got plenty of experience working with a range of different elevations but once the grade gets above around 10% you could be up for a challenge. Your site works contractor can offer some specialist guidance on building a shed on a steep slope.
Before any actual building can begin, we will always get your design certified by one of our expert engineering partners. Your structure is carefully reviewed, taking into account the terrain and other factors to ensure we use the correct structural components for your building.
This means we can ensure that even if you’re building on a slope, you’re still going to end up with a great structure.
