>>2929315
>Not Shingled?
Felt is the common UK roof for sheds. No shingles on top.
In America we use the same quality roofing for our sheds as our houses.

>>2929331
If the felt still has structural integrity, paint can work. I would probably replace the ridge felt regardless.

>>2922167
>>2922252
Typical shingles have a 20 year service life.
They do make 50 year shingles which are a lot more durable but few people buy them. The reason is that Americans don't live in a house for more than a few years, so they don't bother investing in long term functional improvements. Instead they invest in superficial things that will boost resale value.