How do you put a tarpaulin on a roof?

1Why fixing a tarp is a roofer's job

A tarp looks like the simplest repair there is. In practice it asks someone to climb a slope that is usually wet, often windy and sometimes missing tiles, then to handle a large sheet of plastic that behaves like a sail. One gust can fill the sheet and pull the person holding it off balance.

The roof itself is part of the risk. Slipped or cracked tiles shift under a boot, slate is slick when damp, and a flat roof that has been leaking may have soft boards beneath the covering. Ladder and roof falls hurt householders who go up expecting a ten-minute task.

A roofer brings proper access, a harness or scaffold where needed, and the experience to know where the structure will take a fixing. If you cannot see a safe way to reach the damage from the ground, leave it to someone who can. Our page on who fixes a leaking roof explains who to ring first.

2Battens, overlaps and how the sheet is held

A tarp that stays put is fixed to the roof, not laid on it. The usual method runs the sheet from well above the damage, over the ridge if that is the nearest high point, and down past the damaged area, so rain sheds onto the existing covering rather than behind the plastic. Water must always run over the cover, never under it.

Battens are the strips of timber that make this work. The edge of the sheet is folded round a batten, or a batten is laid on the folded edge, and the batten is then screwed through to a rafter or an existing roof batten. That spreads the pull along the whole edge, instead of concentrating it at a few holes where a gale tears the plastic.

Nailing straight through bare sheet at a handful of points is the usual reason a tarp is found in the garden by morning. The fold, the batten and a fixing into the structure are what hold it.

3Bricks, sandbags and buckets do not work

It is tempting to throw a tarp over the damage and hold it down with bricks, sandbags or buckets of water. On a pitched slope that cannot work. Anything heavy placed on the sheet slides, and as it slides it drags the plastic, rips it, or drops the weight onto people or a car below.

Wind makes it worse. Air gets under a loose edge and lifts it, and once one corner goes the rest follows quickly. A flapping sheet also chafes against the tiles and can crack more of them.

Weights have a place only on a flat roof, and only as a short-term way to stop a sheet blowing away until a roofer arrives. They are not a repair, and a pool of water gathering on the tarp adds load to a roof that may already be weakened.

If you are tempted to go up yourself, what to do about a roof leak sets out safer steps first.

4What you can usefully do while you wait

Your work is indoors and on the ground. Move furniture and valuables clear of the wet patch, and put a bucket or washing-up bowl under any drip. If a ceiling is holding water, do not ignore it; it needs a controlled release, and the page on a bulging ceiling covers how.

Photograph the damage from the garden, from a window if you can reach one, and from inside the loft with a torch. Note the date, the weather and the moment you first noticed it. These records are worth having if you make an insurance claim later.

Tell the roofer what you can see and what the roof is covered with, so they bring suitable materials. Keep children and pets out of the area below the damage, and keep clear of any tiles that still look loose above you. If the roof is flat or low enough to see from an upstairs window, describe it rather than going out onto it.

5A tarp is a pause, not a repair

Even a well-fixed tarp is temporary cover. It keeps the next shower out while the cause is found, and it needs checking after strong wind because fixings loosen and sheets stretch. How long one can stay on depends on the weather and the fixing, so no fixed number of weeks can be promised. Sun and flapping wear the plastic down, and a sheet that has gone slack lets rain pool in the folds, which is when it starts to leak at the fixings.

The permanent repair follows the survey. We trace where the water has been entering, send photographs of the roof itself, and put one total price in writing. The cost of the emergency visit is covered on the emergency roof repair cost page.

If you are claiming, mention the tarp to your insurer at the outset. The storm definition guide and the loss adjuster page explain what comes next, and the main emergency roof repairs page lists the other faults we cover.