How would you insulate this loft roof?

[tapir]

Hi all.
The loft isn't insulated roof-side, it's felt and tiles. The floor below is very well insulated, but I want to insulate the roof as well so that I can use the loft space for climbing training, weight lifting.

the roof: We had an extension a few years ago, and all the roof supports were upgraded, with the existing ones left in-situ. The new supports have a depth of about 200mm to the roof tiles, with the old structure having a depth of around 60mm. The roof is currently well ventilated at the so fits along both edges, there are no tile vents, and it would be difficult to add these due to the roof height and pitch - would require a lot of scaffolding.

My thoughts: I need a vapour barrier, and something like Kingspan or Celotext, and to leave enough of a space behind this layer to allow ventilation.

I have no idea though, what solution I need to achieve this between each rafter. Where the rafters meet the purlins, there's probably not enough depth to cover with large sheets of insulation, so I'm assuming that I need to insulate between each rafter. Where the roof structure flattens out I'm going to leave the space behind it, just insulate on top.

I've attached some photos as it's easier to see what I'm talking about
thanks all!

 

[freddiemercurystwin]

If you have no ridge ventilation and you are not prepared to either fit ridge ventilation or a tile vent at the top of the roof in between each rafter then insulating between the rafters is not to be recommended. Any moisture getting through the insulation will simply have no where to go and will condense on the underside of the felt.