Determining Relative Elevation, DIY-Style

Construction & Contractors Blog

There are plenty of reasons you might want to conduct an engineering survey of your own property. You might be considering building an extension or some other small structure, for example, and need to know the elevation of your land before you begin. Leveling--figuring out the relative elevation between two points--is widely considered to be the simplest form of engineering survey, and there are two main ways you can figure out levels on your own at home without a great investment.

• To find out if a particular patch of land is flat--to help you build a raised bed for vegetables, for example, or before beginning simple construction work on something like a shed--you can make your own water level quickly and easily. Water levels are based on the fact that a body of water not subject to outside influences such as tides will be the same level at one end as they are at the other. All you need to build your own is a large plastic jug (such as the kind used to sell big bottles of vegetable oil, or the sort petrol often comes in), a length of flexible plastic tubing (available at any hardware store) and two wooden stakes or dowels (also available at any hardware store). When you're all set up, you'll be siphoning water into the tube from the jug and then marking the dowels to show whether the two points are in fact level. For more information, look up a how-to guide or a tutorial video--you'll be amazed by how simple it is.  
• For very simple work, there are now several smartphone apps that can be used to turn your smartphone's GPS system and internal pressure sensors into an altimeter. The reading you get won't be 100% accurate, but it will be good enough for basic purposes like determining how high a hill on your land is. There are a wide variety of apps available for this purpose; search through the ratings and reviews to find one that will work for you. If you'd rather not use your smartphone for this, you can look into purchasing an altimeter watch--they're more expensive, but they're also more accurate.

Before you invest your time, money and energy in acquiring this equipment and learning how to use it, however, it's important to consider whether you might be better off hiring a professional land surveyor. The relative elevation between two points is a vital statistic for anyone hoping to build a trailer home or pier, and you should be able to calculate this yourself. You can also quite easily figure out whether or not your new raised beds are flat, or satisfy your curiosity about the height of hills on your land. If, however, you need to know something more technical than that--such as the absolute elevation above sea level of any particular point in your property, which is necessary for flood plain determination or to get an elevation certificate--your best bet is to call in the professionals. In these circumstances the cost of their services will be more than accounted for by the potential losses you could incur if you make a mistake, and many aspects of land surveying are highly technical work requiring trained expertise. 

28 July 2016