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Redo the waterproofing of a roof

Redo the waterproofing of a roof

Checking and maintaining the waterproofing of roofs is essential in the maintenance of a house. Above all, remember that working at height is dangerous and must be approached with great care.

Humidity, a danger!

A crack in a tile, slate or flashing seems harmless. However, it constitutes a water infiltration route and, in the long term, can lead to the degradation of structural members. It is therefore necessary to regularly check the condition of the cover. This monitoring is particularly important if the attic is insulated, because then the cover is not visible from the inside.

What is a flashing?

A strip of mortar or metal caulk the junction between two parts of the roof or of two planes, and in particular at the right of the chimney stumps. In old houses, the flashings were sometimes made of lead. Today, they are most often in mortar.

Safety first

The main repairs concern the replacement of roofing elements and the waterproofing of flashings. For these, there are many products that make intervention easy - without the need to remove the old mortar joint and redo it. The main difficulty of this work is the always perilous nature of tinkering on the roof.

Safety rules

• Whenever possible, access the roof by a skylight or a sitting dog rather than by the ladder.
Do not press the ladder directly on the gutter: use a spacer, that is to say an element adaptable on the ladder and allowing it to be pressed on the wall.
The ladder must have a sufficient inclination so that you can climb it without risking to fall back.
Place the ladder feet on a stable floor and block them.
Use roof ladders with hooks for attachment to the ridge. They have casters and the ladder must be turned over to slide it up to the ridge. Do not step on the cover elements.
Wear non-slip shoes.
Do not work on a wet roof.
Use a safety harness, but never hang on the chimney stack, especially if it is brick. Attach the harness to a securely secured ladder or, when possible, to a structural beam.
Do not carry heavy objects which could destabilize you.
Use a bucket and rope to raise and lower tools and materials. Do not load yourself to climb the ladder.
Only go up on the roof in full possession of your means - and especially not after a good meal.

On metal roof

• Check the condition of the welds and joint covers.
Brush the rusty parts and apply an anti-rust paint.
Clean with a high pressure device.
Seal open holes and joints with roofing putty.
If necessary, waterproof with a resin-based product.

Tools and materials

• Ladders with spreader
Safety harness
Carpenter's hammer
brushes
Waterproofing tape Savoir tout faire © La maison rustique - éditions Flammarion, 2005