Sometimes, although a nest may be in a roof void,attic or bush, you have no access to get to it, you then need to attack from outside the roof void or from ground level if the wasp nest is in a bush or tree.

The best piece of equipment for this job is the 18 foot reach DUSTICK. Use RENTOKIL WASP NEST KILLER POWDER or FICAM D (professionals only) in the Dustick. You can use the Dustick for nest treatment anything from 3ft to 18 feet away by adjusting the number of extensions fitted. The Dustick has a fairly narrow angled nozzle on top of the wasp killer dust chamber, which allows for reasonably precise dust application into small nest entrance holes or under roof tiles. This equipment is quite expensive but built to last and very versatile for wasp control purposes.

A cheaper option is the WASP GO GO KIT. , which has a reach of 3 metres (10 feet) and a new model that will reach 4 metres (13feet).

Another good Wasp Nest Killer product is the Birchmeyer DR5 DUSTER, cost will be around the same as the Dustick but this system has much higher pressure and can blow the insecticidal wasp killer powder under wall cladding and has the power to blow the powder many feet into a void. There are also multiple nozzles available for accessing difficult locations.
Wasp Killer Equipment can be viewed and orderd here.