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| Flag on edge Retainer |
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Stone flags used as an earth bank retainer |
Concrete flags used to retain a raised garden |
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Most types of flags/slabs can be used for this very simple retaining structure, as it is the concrete haunching and bedding that provides most of the strength. By using a decorative or riven type of flag, a pleasing finished effect can easily be achieved, creating different levels within a garden or landscape.
The flag is laid on a concrete bed at an angle of around 5° from plumb, leaning back into the bank. The concrete haunch is packed into the rear and at the front toe of the flag, to prevent it slipping forward. |
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This structure is not suitable for retaining banks greater than 900mm in height, or for supporting heavy or elevated structures, such as driveways and car parks more than 450mm high; for these types of construction, a brick-built or system retaining wall will be needed.
This flag-on-edge structure is useful for terracing and retaining smaller banks of earth, but is a bit too heavy for practical use in retaining raised beds in the garden. |
| One of the more popular uses for this type of simple retaining structure is to accommodate a level difference betwen two adjacent pavements. The most regularly observed example of this is the neighbouring driveways which share a common threshold level where they meet the public highway, but then diverge, and one drive ends up being 150mm to 450mm higher than the other. |
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| Note the upstand of the retaining structure on the upper driveway. This is important, as it provides 'check' that will help prevent a vehicle accidentally straying over the edge. On the sketch shown here, the upstand has been aesthetically enhanced by incorporating a small-unit kerb, although, in theory, 50-100mm of the flag itself could be left 'sticking up'. | |
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In this example, a flag-on-edge retainer has been used to create a simple plinth surround to a sign post. Note that the flags have been carefully mitred at the corners to ensure a neat and tidy finish without compromising the backward tilt of the flags or exposing unsightly 'ends'.
The plinth has been filled with concrete and then finished with a steel float to give a smooth finish. Notice that the concrete has been laid with a small amount of fall to ensure surface water (rain) drains away adequately. |
Other Hard Landscape Features on this site... |