There is no hard and fast rule about how deep a hole should be dug for receiving a sign post but the table below is a rough guide and is a good starting point. If you are at all unsure, please contact your local civil engineering department for confirmation.
Post Height
Planting Depth
1000mm (1 metre)
300mm
2000mm (2 metres)
500mm
3000mm (3 metres)
600mm
Post Foundations - Digging the correct size hole
Here is a rough guide as to what size hole to dig when planting a sign post. Again, if in any doubt, contact your local civil engineering department.
Enter in your depth (x)
mm
Results:
Width of hole (y):
mm
Length of hole(z):
mm
Base Plates
Sign posts should be secured in the ground using base plates. This will prevent removal and rotation of the post after the concrete has set. It can also be easier to our the concrete without having to support the full weight of the post. All our posts come with base plates and end caps
Foundation Sleeve
For situations where the foundations need to be dug before the posts are on site then Foundation Sleeves are the thing to use. These are ribbed plastic sleeves that can be pre cast into a concrete foundation. Sign posts can then be light cast or sand filled at a later time.
Please also see our sign post calculator to see how many posts you actually need for your chosen sign.