How do you secure roof underlayment so it does not blow off?
Where wind gets in
Wind lifts underlayment at its edges: the rakes, the ridge, and any lap that faces into the wind. Once air gets under a sheet, it balloons and tears off the fasteners. Securing underlayment is mostly about closing those edges.
Good practice
- Cap fasteners only. Bare staples and nails tear through synthetic sheets in a gust.
- Fasten the top edge first, then the laps, then the field pattern.
- Tighter spacing at edges along rakes and the ridge.
- Laps facing downhill and away from the prevailing wind.
- Ridge: wrap the sheet over the ridge or cap it temporarily so the top edge is not exposed.
- Check the UV rating. Synthetics have a maximum exposure time; felt degrades and wrinkles faster.
What not to rely on
Bricks, lumber or sandbags laid on top shift and tear the sheet. Tape alone does not hold in wind, and a single row of fasteners along the top is not enough for overnight exposure.
If a storm left your underlayment exposed
Sometimes wind strips shingles and leaves the underlayment showing. That sheet is a temporary barrier, not a roof, and it will degrade in the sun. Get a tarp or temporary repair on it quickly, photograph the damage for your records, and have the roof inspected before the next rain.
See synthetic underlayment vs felt and wind damage to roofs in Georgia.