I have a converted bungalow with the loft space now occupied as 2 bedrooms and a bathroom. In the main bedroom there is a recess with stud walling surrounding the chimney breast. A strange noise is coming from the roof area in this room. By putting ones ear to the slopping ceiling this is more apparent. The sound can only be described as a 'sizzling sound', almost like electricity. Any ideas s to what it could be? Someone has suggested a Wasps Nest. There is no human access to the space for as I say this is a loft conversion.