I am going to be putting in airtight membrane on the ceiling joists of my bungalow with 50mm insulated plasterboard underneath, cold roof. In relation to the electrician's part, is there any way that I could avoid using batons and counter batons between the membrane and the plasterboard? For instance, would the following sequence work:
1)get walls chased
3)put airtight membrane around windows and to the underside of the joists. I plan not to tape the membrane to the block work at ceiling level just either side of where a chase comes down the wall so as to leave room for pushing wires down, then tape it.
4) electrical 1st fix whereby the electrician leaves the wires (lights,smoke,carbon alarms) down through small holes in the membrane. (Do attic wires run along over, under or drilled through the joists?)
5) I screw my insulated plasterboard to the ceiling and then carefully drill appropriate sized holes to meet the wiring hole for the light wire.
6) internal plastering happens.
7) Regarding Spotlights- Once the electrician has them installed, Do I come along and tape an airtight hood or box over them onto the membrane? I then let the attic insulation (fibre wool) come up alongside these hoods but not covering them?
Any suggestions or corrections to this sequence of events? Thanks.