If you reside in England, Scotland, Wales or Northern kado unik, kado ultah unik and need to transport ladders, scaffolding, canoes, tipi poles etc here are the official legal requirements.
They can be on the VOSA - Vehicle and Operator Providers Company Operational Manual under Section 26.
Significantly less than 1 metre: No requirement
1m - 2m: Render obviously visable (ie- red ribbons, high vis vest, etc) "Clearly visible within an acceptable length to a person using the road"
2m - 3.05: Rear marker board required:
Over 3.05 metres: 2 working days to the police should be given.
Projections and overhang to leading:
0 - 2m: No requirements
2m - 3.05: Front and aspect marker board.
Overhang above 3.05: 2 working days notice to the police:
What the VOSA manual doesnt specify can be whether or not you could have a two metre front overhang and two metre rear . We contacted VOSA and had been informed that was the case. Therefore, legally you can have a four metre total overhang without the need for a light board.
In practice however, should you have 3 metre mini and desire to bring seven metre ladders, whether you are legally eligible for carry them or not really, this can look very unsafe so you will likely get stopped (You may even need to consider the weight of your poles and the vehicles MAM - the weight it really is allowed to carry)
If the size of the strain you are holding looks unsafe for you, chances are it'll look unsafe to other road users and the authorities. A print out of the VOSA manual kept in your car or van to verify your load is at the law will certainly save you a lot of time if you're stopped.