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    Why do you need to build a drainage trench around a home's foundations?

    Published on 28 February 2016, Sunday, 8:43 PM

    If you are building or renovating, it is safe to say you'll want to make sure the foundations of your home are strong and remain that way for a considerable length of time.

    One of the easiest ways to do that is to construct a drainage trench when you put the foundations in. To do this you will need to organise an excavator to do the hard yards for you.

    Without an adequate drainage system, water can soak into the soil around the outside of your foundation, moving under footings and causing the building to move or settle.

    This can lead to long-term problems with structural integrity as wood can rot, doors and windows can stick and stairs may even rise and fall as a result.

    Here is a rough guide to the different types of drainage trenches to consider.

    Foundation French Drain System

    This kind of system involves trenches filled with gravel surrounding a perforated drain pipe. In order to increase efficacy, either the entire trench or just the pipe itself is usually covered in filter fabric. It is used to stop soil from washing into the stones and plugging up the drain.

    The trench is then hidden with a layer of grass. These are generally used in wetter areas as they are good at collecting the water that often accumulates in marshy or boggy areas and moving it away from foundations.

    One mistake that often trips up DIYers is installing spouts. While this might seem like a great idea, it can actually create such a strong flow of water that the drains fill up and push water back into the ground.

    Rubble Trench Foundation

    This kind of trench is a continuous footer located around the entirety of the structural perimeter. It is usually dug as deep as the ground's freezing point in winter and then filled with stone and often topped off with a grade beam.

    The Earthen walls of the Middle East and Africa featured rubble trenches, proving this idea has been around for many years. Those trenches were built on shallow ditches and filled with loose rock.

    Rubble trenches are unique because they provide both water drainage as well as a low cost foundation system - may older structures featuring this kind of trench are still standing strong today to tell the story.

    Rigid drain pipe might be a better choice for this kind of drain because it is easier to establish and is one way to avoid the creation of any low spots where sediment could accumulate.

    Nathan Mills portrait image
    Nathan Mills
    Nathan is a seasoned Kennards Hire team member passionate about empowering DIYers in their projects. He loves everything DIY and brings together years of equipment and project experience to help customers get the right tools for their next job.