You have a cold spot in the roof space where moisture is trapped if you havent got a breathable roofing felt on the roof there are options that can reduce the condensation the cheapest way is to install either slate or tile vents or ridge vents buy this is more expensive and having the insulation between the rafters will also be of better use to you.
Monofoil roofing felt.
These companies are known for quality dependability and a great finish every time.
It also offers fire resistance required for home construction.
Roofing felt also known as tar paper provides a protective underlayment over the roof deck and beneath the shingles.
Gaf shingle mate 36 in x 144 ft 400 sq ft felt roof underlayment.
Sometimes called roofing felt underlayment roofing tar paper or roll roofing this is a layer of protection installed between the roof deck and the roofing shingles.
Most roof felts can be used as a shed roof felt but we ve hand picked the range below as our recommended shed roofing products.
Roofing felt for sheds comes in torch on bitumen and self adhesive bitumen from manufacturers like iko and icopal.