torn /rotted roofing felt/leaking! help!

[unclealbert]

Hi,im hoping for some advice,so here goes..
In my loft the felt is quite deteriorated in small areas and bulging sagging in others with old birds nests and god knows what,in scattered areas (thats prob only about 15% of the overall roofcovering though).
I now have quite a constant leak,and what I want to know is can I refelt
the roof without removing any tiles( Iv read a post already which says I cannot). No way Im geting up on the roof!!Then next is to call a roofer for a quote which I imagine will suggest removing all the tiles and refelting / fixing all prob tiles/chiney lead coverings ect. This I imagine is going to be an expensive job,scaffolding ect.which leads me to my next point...
CAN I cut away all the felt off the inside of the roof /clean up the inside of the slates and use that spay foam insulation I have read about since I noticed the leak ,two days ago!! Would this be a feasable or cheaper option do you think? I hope my buildings insurance will cover it but wont find out till tommorrow,anyway thanks for any help/advice you may have to offer,so,thanks!

 

[Thermo]

you will need to re felt from the outside as the felt will be held in position by the tiling battens nailed through it. it is a fairly simple job to do from the outside for a roofer.

i would not under any circumstance consider the spray foam insulation. it covers all the roof timber which means it is unable to breath and can lead to the roof rotting.

 

[greengrass]

You first need to find out what is causing the leak before hand then you might not have to re-felt. Foaming as has been said smothers the timbers and causes eventually dry rot, and wet rot where the un-attended leak will be.

Unfortunately it's a roofers job and expensive. My answer would be to find the leak cure that and double the insulation in between the ceiling rafters. I don't like felt is does play havoc with timber restricting breathing.

If you do double ceiling rafter insulation make sure you keep the eaves clear to allow a flow of air throughout the attic. Don't insulate under water tanks let some warm air in to help prevent freezing, well that's what I've been told by a plumber so keep mine clear. Slide loose boards [6mm mdf or h/board] between the joists around the base of the tank.