Quick take

• Best use: Short‑term cover for small to medium roof or wall damage between storms.
• Limits: Billowing and uplift at 35–50+ mph winds, leaks at fasteners and seams, abrasion at edges.
• Upgrade path: For large, complex, or multi‑day rain events, choose shrink wrap or reinforced membranes.

What blue tarps can do

• Provide a temporary water‑shedding layer over missing shingles or small decking losses.
• Divert rain away from penetrations and direct it toward gutters when properly lapped.
• Create short‑term wall or window protection when combined with battens and sealant tape.

Where tarps fail in high winds and heavy rain

• Uplift and billowing: Wind gets under loose edges and turns the tarp into a sail.
• Leak paths: Every staple or grommet can be a drip unless backed by underlayment and battens.
• Abrasion and tearing: Sharp shingle edges, ridge caps, and metal trim will saw through fabric.
• Water pockets: Sagging spans collect water, add weight, and rip at fastener lines.

Wind thresholds and expectations

• 0–25 mph: Well‑secured tarps with battens generally hold for short periods.
• 25–40 mph: Edge detailing becomes critical. Expect noise, some billowing, and higher leak risk.
• 40–60 mph: Many consumer tarps will tear or pull fasteners without continuous battens and structural anchoring.
• 60+ mph: Not recommended. Use reinforced membranes or shrink wrap installed by trained crews when safe.

Materials and sizing

• Fabric: Heavy‑duty polyethylene or reinforced tarp, 10–16 mil preferred. Avoid thin, off‑brand tarps.
• Underlayment: Self‑adhered ice‑and‑water shield beneath laps and fastener lines to seal punctures.
• Battens: 1×3 or 1×4 lumber to clamp edges and distribute load. Pre‑drill to avoid splitting.
• Fasteners: Exterior screws with washers into structural members where possible, not just sheathing.
• Size: Choose a piece large enough for 12–18 in overlaps beyond the damaged area in all directions.

Installation pattern that works in wind

1. Prep: Remove loose debris. Dry contact areas. Lay self‑adhered underlayment over holes and along planned fastener lines.
2. Lay tarp from low to high: Start at the eave and run toward the ridge so laps shed water.
3. Battten the windward edge first: Install a continuous batten with screws every 6–8 in. Avoid relying on grommets alone.
4. Secure sides with continuous battens: Keep the tarp taut without over‑stretching. Add a second batten if edges flutter.
5. Top termination: Tuck under intact shingles if possible, then batten. Add a drip edge or sealant where needed.
6. Eliminate sags: Support long spans with additional battens or intermediate straps to prevent water pockets.

Roof‑specific notes

• Missing shingles only: Underlayment patch, then tarp. Keep battens perpendicular to water flow.
• Decking loss: Infill with temporary sheathing first, then underlayment and tarp or upgrade to shrink wrap.
• Ridges and vents: Cap with underlayment before tarping. Plan for eventual ventilation to avoid condensation.

When to choose shrink wrap instead

• Damage spans multiple planes or wraps around corners.
• Forecast calls for days of rain or gale‑force winds.
• Access doors are needed under cover. Zipper doors integrate well with wraps.
• High‑visibility or coastal sites where wind exposure is extreme.

Field checklist

• Safety first: treat downed lines as live. Use fall protection and proper ladder tie‑off.
• Weather window: avoid installs during lightning or unsafe gusts.
• Underlayment and overlaps in place before screws go in.
• Continuous battens on all windward edges.
• No sags. Re‑tension and add supports to prevent water pockets.
• Photo documentation before and after.

FAQs