Leaky roof? How to find the leak and seal the roof yourself

A leaking roof is almost always discovered too late. The water appears as a spot in the ceiling in a completely different place than where it penetrates, and by that time the moisture has already had a hold on the insulation and rafters for a while. Here you will get an overview of how to find the leak and how to seal the roof yourself without tearing it all down.

How to find the leak

Start from the inside. Follow the stain on the ceiling or rafters upwards, because water runs across the substrate before dripping down. The leak is therefore almost always higher up than where you see the damage.

Then go up to the roof on a dry day and look for:

• Cracks and dents in the roofing felt, especially in overlaps and joints
• Loose or open edges at flashings, chimneys and vents
• Water that remains after rain is a sign of a low point.
• Moss and algae that retain moisture and draw in the surface
• Nails and screws that have worked their way up

Where the roof most often leaks

On flat roofs and roofs with a low slope, things rarely go wrong in the middle of the surface. It's the joints that fail. Overlaps in the roofing felt, the transition to the cornice, flashings around chimneys and skylights, and all the places where two materials meet each other and work differently in heat and cold.

The same applies to eternit roofs, slate roofs and roofs with zinc cladding. The material itself lasts a long time, but the transitions become leaky first.

How to seal your roof yourself

A liquid roofing membrane is applied as one continuous layer over the entire surface, including the joints. There are no new overlaps to watch out for afterwards, and you don't have to tear off the old roofing felt.

The procedure is the same regardless of whether it is a garage roof, a carport or a flat roof on the house:

1. Clean the roof. Remove moss, dirt and loose particles. The surface must be dry and firm, otherwise the membrane will not adhere properly.
2. Repair the rough. Dents and holes should be filled first. Large cracks should be reinforced with fabric.
3. Roll up the membrane. Use a brush on edges and around flashings, and roll on large surfaces. One coat is enough.
4. Let it harden. Avoid rain for the first few hours. After that, the roof is sealed.

A single layer Luna Roof liquid roof membrane covers up to 13.3 m² per 20 kg bucket and lasts up to 40 years. It is seamless and elastic, so it follows when the roof expands in the summer heat and contracts in the winter.

When should you contact a professional?

If the surface feels soft when you step on it, or you can see that the insulation is wet, then there is more to the problem than just a leaky surface. In this case, the structure must be opened and dried out first. The same applies if the roof has been hanging and collecting water for a long time.

If, on the other hand, the roof is just worn, cracked or leaking at the joints, you can easily fix it yourself in a weekend.

In short

Find the leak higher than the stain. Check joints and flashings before looking at the surface. Clean thoroughly and apply a liquid membrane over the entire area instead of patching in individual spots. This will keep the roof sealed for many years to come.

If you want to see what it looks like on real roofs, we have collected before and after pictures below. our cases.