I am thinking about insulating the highlighted stud wall with 100 or 170mm loft roll secured in place with tape or netting. Is this ok? Obviously the thicker the better. But is it the best thing to do? Will it do? Will 50mm sheet insulation be any better for this area? Obvioulsy it would be easier to fit in place as it can be cut to fit the gaps, but it will be a lot more costly than the £3 per roll of loft insulation I can pick up. This is why I would prefer to use the loft roll, I'm not aware of any reasons not to.. there is plenty of ventilation behind in the void.
Thank you for any comments