I don't believe it is illegal, beyond the generality that it's illegal to endanger people and strapping something likely to greatly increase the wind load to a Heras fence potentially endangers people. Even if you use a partial solidity sheeting, you'll still need to check wind loading on the fencing. The only real advantage of using a proprietary sheeting is that (hopefully) the effective solidity will be well characterised, where bamboo roll will be uncertain and variable (but not worse than solid - you could analyse it as if solid, and it won't be worse than that).

You will need a temporary works design for the heras fencing that will cover the overturning moment once it is sheeted. This should cover the design of suitable controls i.e. stays, bracings etc to ensure that the fence will not get blown over. You will also need to ensure that the fence erectors follow this design also. allan

And once you've installed the additional bracing / shoring - you lose the flexibility benefit of using heras over fixed hoarding. I know that there are some places where a builders cheek peek must not be on display (a cemetery?) - but I suspect there are a lot more where people may be a little over-sensitive.. ? Surely the contractors Construction Phase Plan identifies the sort of fencing required at different stages of the project and has been "approved" as sufficiently developed by the CDM-C? (He said with tongue very firmly in cheek). And at the start of the project did the client tell the CDM-Co-ordinator that concealment was a client requirement or site condition before work commenced as part of the information pack to be passed to the contractor? Heras fencing is designed to stand up only as it is made. I know of a project where around 90% of a very large quantity of Heras blew down and had to be reinstalled nearly every week for around eight months until we were able to convince the erectors to 'double clip' and triangulate at regular distances (as required by the manufacturer....) Basically - if you've agreed they can use Heras (to improve flexibility) then accept they are using Heras and don't try to change the rules on them 'after the event'. Steve