I'm installing a new floor in Victorian terrace loft space of about 8m X 4m. My structural engineer has calculated 75x195 joists at 400cm c/c supported by wall plates and central supporting walls. The existing ceiling joists are strengthened by strings that run angled side to side which will have to be removed to install the new joists. I'm thinking to sister the ceiling to the new floor. As this is only to support the ceiling, can anyone advise on the sistering method? do I need to sister with bolts or can I get away with screws? What size and spacing would be appropriate? Any help much appreciated.
