Sealing Roof Drains and Vent Pipes

1. Worn-out drains

Around the old drains the material had rottedWood rotDecay of wood caused by fungi when it stays damp for a long time. Rotten wood goes soft, gives when pressed or crumbles, and can't be saved with paint. and rusted, so water was getting into the slab easily.

2. The opening in the parapet

In this corner the water leaves through an opening at the foot of the parapetParapetThe low wall around the edge of a flat roof or balcony. The joint between it and the floor is one of the most common places for leaks.. The area is cleaned before anything goes on.

3. First coat

The white waterproofingLiquid waterproofing membraneA waterproofing product applied as a liquid by roller, brush or spray. Once dry it forms one continuous, flexible membrane with no seams. is spread around the opening and carried inside it.

4. Reinforcing with fabric

Reinforcing fabricReinforcement meshA mesh or fabric, usually glass fibre or polyester, set into render, a coating or liquid waterproofing to hold it together and stop cracks from opening. is laid into the wet material, following the shape of the opening, so the coating does not crackCrackA split or gap in render, concrete, a wall, a coating or wood. Fine cracks are usually only on the surface; ones that grow, keep reopening or run diagonally need attention. at the corners.

5. The base of a vent

The base of the vent pipe is first closed with a piece of membrane.

6. Mesh around the pipe

Reinforcing mesh goes on top and wraps around the pipe.

7. Coating the pipe

The white material covers the base and runs up the pipe, so water cannot find a way in at the joint.

8. The vent finished

A white, reinforced base, bonded to the rest of the roof.