Loft Insulation

[wkdhd]

I want to improve my roof insulation without getting over complicated about it.
The house is a 1980 3 bed terrace. The roof space is felted and tiled so it is all quite clean up there. It has insulation between the joists.
All I was going to do was to lay 200mm cheap something across the joists. It is part boarded and I was a bit stuck with this until I saw some insulated chipboard panels in B&Q today. They look easier and sturdier than the wobbly stilts with panels on top although more expensive. I only need a small area, Christmas stuff mostly. I'll board a path to the tank and insulate over the top of it, it has something already. These insulated boards will make getting into the loft from the loft ladder much easier.
3 Questions

1) I can't see any problems with this but people seem to make the whole thing complicated.
2) There are vents from the upstairs ceilings into the roof. I don't know why but presumably if I made little plasterboard tunnels through the insulation for them they would be fine.
3) The wiring for ceiling lights is presumably fixed to the joists. Do I need to make plasterboard structures round them through the insulation? They only have a low powered bulb hanging on them so I can't imagine there is any heating effect at all.

 

[AronSearle]

1. don't see problems with laying insulated panels over joists as long as they are vapour permeable.

2. EH?, no, there should be no holes from the habitual space to the roof, any services (such as extraction) should be piped to the outside.

3. Probably fine, though *if* it caused a fire your insurance would screw you. If the wire is long enough, put it over the insulation.

 

[wkdhd]

Thank you.
The vents are odd, there is one in each room upstairs and on the landing. They are around a foot by 3 inches and have a little wheel which used to allow them to be shut. I've not looked but suspect the current insulation may be on top of them.

 

[AronSearle]

Very odd.

You don't want warm internal air, going into the cold loft space, will cause condensation and timber decay. Probably not an issue so far because the roof was poorly insulated, and I assume well ventillated.

Block them up.

 

[wkdhd]

I'll do that. Thank you