Manky roof felt on loft conversion

[john k]

I am thinking of adding a loft conversion to my 1950s bungalow. On inspecting the roof, the tiles appear to be in good condition but the old original underfelt has repairs all over it. There are no leaks which I can see. I understand that holes in the felt are not all bad as they can supply plenty of air into the 50mm gap required by building regs between the tiles and insulation and many houses built prior to 1930 didn't have any underfelt anyway! Also I reckon the insulation will stop the flexing of the felt on windy days and may actually help preserve it.

But here's the rub! With old 1950s underfelt it is obviously breaking down and will continue to do so. So, if I do spring a leak via a cracked tile and water does manage to get between the tiles and insulation I won't see it, as even the plasterboard will be foil backed.

The question is, should I have it re roofed (will obviously cost me an arm and a leg) or just go ahead and hope for the best, or is it not really an issue? I will be interested in any comments or thoughts on it.

 

Edited September 29, 2018 by john k
wrong

[Cpd]

Tricky situation.

 

My main house roof is slate and well over 100 years old. The slates  are tiny as they were mined locally, just down by the beach! There is a lot of nail rot and slates need replacing every year. In windy conditions that is very often.... water blows up under and around the slates and gets onto the sparking boards (there is no felt and never has been) but the very nature of the roof makes it a very draughty place so the water on the sparking boards dries out before it caused a problem.....  even though this is a mad situation it works. I will however rebuild the roof one day and reslate  it with  a better slate and a breatherble roof membrane. 

 

Back to you, it depends on a hole bunch of factors like, is this going to be home for a long time, can you afford to do the work, can you do it yourself, are the existing tiles in good order. 

 

Personally i I would like to have the work done and then forget about it for ever ! But for me it will have to wait until I can afford to do it. 

 

May be worth looking at getting some quotes, if you can reuse the existing tiles that could be a big saving. You would need to identify them and get a bunch of spares for the reroofing as some / many could get damaged in the stripping of the roof.