Home insulation on sloping ceiling - is this ok?

[stonka]

Is this ok?

I ripped down an old lath and plaster ceiling (immedately regretted it) firstly doing an Asbestos Test via online lab - that was clear.

Then put insulation straight over joists like this with 48MM thk insulation, and foam glue onto the walls (c. 5mm thk foam bead) : left air gap between joists... Aluminimum taped joints. Used 75mm black, coated screws

Then plasterboarded over top like this:

 

[freddiemercurystwin]

Yes, assuming the void is ventilated at the eaves and where it meets the wall above the flat bit.

 

[stonka]

any known building reg that need to be followed or is this fine for DIY'ers? Was expecting someone to givce me a reason why couldnt go across the joists... or something about moisture and not allowed to do this way.....!? Certainly works well!

 

[freddiemercurystwin]

Requirements for ventilation is a requirement of The Building Regs Part C, it doesn't matter if your'e a DIYer or not, any warm air that get's through your insulation will condensate on the next cold surface it meets ie the underside of the felt therefore that void ought to be vented.

 

[stonka]

Ok, so either way, it should be seen as much better than it was as there is now an alu foil vapour barrier whereas before there was ropey lath and plaster. Was just wondering whether this is classed as creating a 'cold roof'? As less heat now leaking out....