Yes did three floor of offices that has these pest living in them.
First and formost You must wear a mask when inspection loft, due to diseases ect. and you mustmake sure it is sufficent for this.
Assuming that there are wooden beams and that, these will have to be sprayed with a suitable disinfectant before any cleaning can commence. When udertaking the cleaning you will have to wear disposable overalls, gloves and mask. Any contamineted wasted has to be double bagged and labled pidgeon waste and disposed of as per your local authority's instructions.
The biggesti ssue is H&S
Petra