Loft Problems for a new member (advice needed)

[barcabod]

I would like to plasterboard the whole lot out (up to the purlings ) so as to make it look like a decent room not just a storage black hole,although thats what it will be used for.My idea is to board to just behind the purlings then plasterboard down to the flooring from the purling after putting a stud section up.Also what gap would you suggest to leave around the edges when i put the roc wool insulation between the joists.Then plasterboard the rafters(even though theres no felt under the slates(would that be ok?).If it is ok would you suggest the alububble then foil backed plasterboard or just foil back plasterboard?Im a bit worried in case the roof leeks although its sound at the minute and has been for a good number of yearsThe roof would still breath would'nt it? as im not enclosing it all in,ie behind the purlings both rafter and joist will still be as they are now.Long winded sorry never tried this before ,but have done most of it in smaller degrees.Cheers aspley

 

[aspley]

You will never be able to provide a waterproof barrier from inside the loft....the only way you achieve that is with the roof tiles on top of under slaters felt sandwiched between the lath and rafters. The tiles themselves should be watertight, the felt is a good backup in the event of a leak through the tiles. The felt laps down under the tiles into the guttering to take any water away.
So, having said that it follows that any water ingress under the tiles will fall on whatever you place under the rafters....bubble, plasterboard..whatever. Any water that may come through cannot possibly make it's way to a safe haven...it will simply fall to the floor at some point.
I would use ordinary plasterboard without any backing then, if you ever do have a leak it will in all probability show itself on the board and allow you to carry out a repair.

 

[barcabod]

Thanks for all your help mate will go down that route i think,maybe see you in the cap and gown next time we play you lol