How to Tarp a Leaking Roof in an Emergency, and When Not to Go Up at All
A tarp is a temporary fix for a dry, calm window. Never climb a roof during a storm, and never nail through the field of the tarp.
- Advanced
- 1 to 3 hours
- Updated
The short answer
To tarp a leaking roof, wait for the wind and rain to stop, use a heavy-duty tarp that reaches at least 4 feet past the damage on every side and over the ridge, wrap the tarp's edges around 2 by 4 boards, screw the boards to the roof framing, and keep all fasteners outside the tarp's field. Never go on a wet, windy or steep roof. If you cannot do it safely, call a roofer.
When a tree limb comes through a roof or a storm rips off a section of shingles, the next rain will wet the insulation, the ceilings and everything underneath. A properly installed tarp is a temporary cover that buys days or weeks until a roofer can make a permanent repair. It also shows an insurance adjuster that you took reasonable steps to limit damage.
A tarp is not a repair, and putting one on is one of the more dangerous things a homeowner can do. The roof is wet, the weather is bad, and there is a hole. The first decision is whether to go up at all. If the damage is over a steep pitch, a second storey or a large area, leave it to a roofer and work on limiting damage from inside instead. See how to trace a roof leak from the attic to find out where the water is entering.
If you decide to tarp, the method matters. Nailing through the field of the tarp creates dozens of new holes. The right approach uses wood strips that clamp the tarp edge, run over the ridge when possible, and are screwed into framing, not just into loose sheathing.
Tools
- Cordless drill or impact driver
- Tape measure
- Utility knife
- Extension ladder with stabilizer
- Roofing harness, rope and roof anchor
- Headlamp or work light (for setting up before dark)
Materials
- Heavy-duty polyethylene or reinforced tarp, at least 10 mil, sized to the damage
- Untreated 1 by 3 or 2 by 4 boards for edges (furring strips)
- Exterior screws, 2-1/2 to 3 inches
- Rope or ratchet straps for temporary anchoring
- Plastic sheeting or buckets for inside
Safety first
- Never go on a roof during a storm, in high wind, while it is raining or when lightning is possible. Wet roofs are slick and wind can carry you or the tarp off the edge.
- WorkSafeBC requires fall protection where a fall could be 3 metres (about 10 feet) or more. On a steep roof or above the first storey, a harness tied to a proper anchor is the minimum.
- Stay well clear of power lines and downed wires. A fallen tree on a house may also be touching live wires. Call BC Hydro before going near it.
- Do not work alone, and never climb onto a roof loaded with wet snow, a fallen tree or a damaged deck that might give way.
Step by Step
Step 1: Decide whether it is safe to go up
Check the forecast and the roof. Wind above about 30 kilometres per hour turns a tarp into a sail. A wet, mossy or frosty roof is slick. A steep pitch, above 6/12 for most people, is no place for someone without training and a harness. If any of these apply, do not go up. Protect the inside and call a roofer who does emergency work.
Also check what the damage is. A tree across the roof may have cracked rafters, and the roof may not support your weight. Stay off until a roofer or engineer has looked at it.
Watch out: If in doubt, stay off. No tarp is worth a fall.
Step 2: Limit the damage from inside first
Move furniture and electronics away. Lay plastic sheeting over what cannot move. If the ceiling is bulging with water, poke a small hole at the lowest point and let it drain into a bucket, because a ceiling that lets go on its own will bring wet insulation and drywall down at once.
Switch off the power to any room where water is dripping through light fixtures, and keep away from wet outlets. This is the most useful thing you can do in the first hour.
Step 3: Measure the damage and cut the tarp with plenty of overlap
Measure the damaged area from the ground or the ladder. A tarp that only just covers the hole will let water run in under its edges. Plan for at least 4 feet of overlap on each side and uphill. Extend the tarp over the ridge and about 3 feet down the other side when the damage is near the top, so there is no seam for water to run behind.
Use a heavy-duty tarp, at least 10 mil thick, with reinforced edges. Thin hardware-store tarps tear in a day of wind. Fold and roll the tarp into a long bundle so you can unroll it up the roof rather than carrying a large flapping sheet.
Step 4: Prepare the boards and pre-wrap the tarp edges
On the ground, wrap each edge of the tarp around a board, fold the tarp over itself two or three times and staple or screw it to the board from the side. The board distributes the pull of the wind along the whole edge, so no single point tears out.
Lay out the boards and screws in advance. You want your hands free and your attention on your footing when you are on the roof.
Step 5: Clear debris and get the tarp up the roof
Remove loose shingle pieces, branches and nails from the area so they do not puncture the tarp. Do not remove anything attached to the roof that you are unsure about.
Unroll the tarp from the bottom edge upward so it lies flat, with the upper layer over the lower, meaning the tarp goes over the ridge and down the other side, never the reverse. Water must be able to run down the tarp and off, without finding a seam.
Step 6: Secure the tarp at the ridge first
Anchoring at the top keeps the tarp from sliding. Screw the wrapped board through the roofing into the sheathing or rafters on the other slope, about 3 feet below the ridge. Use a screw long enough to reach framing or a solid deck, usually 2-1/2 to 3 inches.
Some roofers prefer to lay a second board on the top side of the ridge so the tarp passes over the ridge and is clamped on both sides.
Step 7: Stretch and fasten the sides and the bottom
Stretch the tarp smooth, without wrinkles that channel water under it. Screw the boards on both sides, then the bottom edge. Place screws into rafters where you can find them, or at least into sound sheathing. Space them about 12 to 16 inches apart.
Leave the bottom edge hanging over the eave or gutter so water runs off clear of the wall. Do not tuck the bottom edge under the shingles, because water will run against the slope and into the damage.
Watch out: Do not nail or screw through the middle of the tarp. Every hole in the field is a new leak.
Step 8: Check from the ground and from the attic
Look for loose corners, flapping sections and wrinkles that could catch wind. Re-check after the next rain and the next windy day. A tarp needs attention, not just installing.
Take dated photos of the damage and the tarp for your insurance claim, and keep receipts for the materials. Then book a permanent repair. A tarp that is left in the sun for months degrades and eventually tears.
Fraser Valley Conditions
Atmospheric rivers and wind storms often arrive back to back, and fallen cedars and firs are a common cause of roof damage here. Tarps put on during a lull are often tested within hours, so do not skimp on the edge boards. In higher areas such as Hope and the upper valley, wet snow loads can also pull a tarp off, and snow on a roof that has a damaged deck may be heavier than it looks.
What a Tarp Cannot Do
A tarp slows water. It does not fix a damaged deck, rotten sheathing or a broken rafter. It also traps moisture under it, so the deck stays damp. Plan a permanent repair within a few weeks, and see how to replace a damaged shingle for small repairs once the structure is sound.
Common Mistakes
- Going up in the storm. Wet, wind and darkness are what cause the falls in emergency tarping.
- Too small a tarp. A tarp that barely covers the hole lets water run under its edges. Overlap by at least 4 feet and go over the ridge when you can.
- Nailing through the field. Every hole in the tarp is a new leak and a place for the wind to start a tear.
- Using a light tarp. Thin tarps shred in a day of wind. Use a heavy-duty, reinforced tarp.
- Tarping under the shingles. Tucking the top edge of the tarp under shingles works in the wrong direction. Water should shed over the tarp, not behind it.
- Leaving it for months. Sun breaks down tarps, and the deck underneath stays wet and starts to rot.
When to Call a Professional
Call a roofer for any damage on a steep roof, above the first storey, from a fallen tree, or over a large area. Also call one if the deck is soft, rafters look cracked, or you can see the tarp location only by going onto a wet roof.
If you cannot reach anyone right away, protect the inside, photograph the damage and report it to your insurer. A roofer can tarp and assess the structure in one visit, and will know how to secure a tarp without adding damage.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Emergency Roof Repair service or the towns we cover.
How to Tarp a Leaking Roof in an Emergency: Questions
How do you put a tarp on a roof without nailing it?
Wrap each edge of the tarp around a 1 by 3 or 2 by 4 board, then screw the boards to the roof, never the tarp itself. The board spreads the pull along the whole edge. Run the tarp over the ridge if the damage is near the top, and keep every fastener on the board so the tarp has no holes in it.
How big should a roof tarp be?
Big enough to cover the damage with at least 4 feet of tarp on every side, and over the ridge and a few feet down the other slope if the damage is near the top. A tarp that only just covers the hole lets wind drive rain under the edges. Buy a heavy-duty tarp, at least 10 mil, and fold it to fit the work.
How long can a tarp stay on a roof?
A well-secured heavy-duty tarp can protect a roof for a few weeks, sometimes a couple of months, but it is not a permanent repair. Sun breaks down the plastic and wind works the edges loose. Trapped moisture can also damage the deck. Plan a proper repair as soon as a roofer is available.
Is it safe to tarp a roof myself?
Only in dry, calm weather, on a low or moderate slope you can reach from a secured ladder, with fall protection and a helper. Never go up in a storm, at night, or onto a steep or wet roof. If a tree has hit the house, stay off until the structure has been checked. When in doubt, protect the inside and call a roofer.
Will my insurance cover emergency tarping?
Many home insurance policies cover reasonable emergency measures to prevent further damage, including tarping, but terms differ. Photograph the damage before and after, keep your receipts, and contact your insurer promptly. Ask what they will reimburse before you spend much, since policies vary in what they consider reasonable.
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This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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