Shed felt that lifts is usually the nails
I found a sheet of shed felt on the path after an October gale. It had come off the eaves in one peel. The nails were still in the roof boards, in a thin line, with torn holes around each head. I thought the felt had given up. The felt had been held by a dozen short nails along one edge and hope along the rest. The wind got under the lap. The nails pulled through. The roof boards were wet by morning.
Shed felt is a bitumen skin. It keeps weather off the roof boards. It is not the structure. It only works if it stays down, in laps that shed water the way tiles do, each sheet overlapping the one below so rain runs over the join, not into it. The nails are what keep that skin on when the wind lifts the eaves. Too few, too short, or rusted through, and you have a sail.
Horticultural fleece fails when it blows off is the same wind on a lighter cloth. Fleece needs pegs. Felt needs nails that actually hold. I would not treat a roof like a bed sheet.
When I check a shed I start at the eaves and the laps, from a firm step, not from a wet roof. I look for popped heads, rust blooms, and a lap that has opened like a lip. If I can lift an edge with two fingers, the wind can lift it. Count the nails. A long run with a clout every foot and nothing in between will go. I want them close enough that a gust cannot get a hand in, and long enough to bite sound board, not just the felt and a crumb of ply. A nail in rotten timber is a pin in cake. Then the job is the board, not a new roll of felt.
Laps matter as much as the count. If a sheet was laid the wrong way, every rain drives under the join. You see a dark stain on the ceiling board first, then a drip on whatever you hung below. I have had that drip on a fork. A shed hook that actually holds a fork will not save the tool from a leak. Hang it anyway. Wipe it after. The roof still has to be shut.
A sagging gutter is usually the clips is a different drop. Felt that has lifted never delivers a clean run to the gutter. If the channel already bellys, a flapping eaves makes the wall wetter. Fix the skin first so the water has a path. Then look at the clips.
Skip staples. They cut the felt and then tear out. Skip short tacks sold in a mixed tin with no length. Skip one thin layer on a roof that already feels soft underfoot. You are wrapping wet board. Skip a patch of leftover felt over a hole you have not dried. The patch becomes a bag of water. Skip leftover felt as a liner in a raised bed. A raised bed that bows is usually the rails, and a bitumen sheet against those rails holds a lake on the timber. Skip climbing on a wet shed roof to chase a flapping edge. If I cannot reach the eaves from a firm step, I wait.
This shows in autumn, when the first real gale finds a lap you have not looked at since spring, and again in winter when the leak stains the boards. I now walk the shed after the first long wet week of October. I look at nails and laps, not at the colour of the felt. A grey sheet that is still tight beats a new roll held by ten tacks. If an edge lifts, I nail it down in the next dry spell, or I replace the sheet properly, laps with the fall, nails that bite.
I do not need a new shed because one eaves lifted. I need the skin to stay on the boards.
If I later add a buy link here, it will be a paid promo.