How can I seal a chimney junction with liquid-applied waterproofing?

ALLESDICHT liquid-applied waterproofing can be used to seal the external chimney junction at roof level. Leaking chimney junctions are among the most common causes of moisture damage to roofs. The transition between the chimney masonry and the roof covering is continually subject to movement from wind loads, temperature changes and settlement; an elastic, crack-bridging rubber membrane accommodates these movements over time.

The rubber-based ALLESDICHT liquid-applied waterproofing adheres to typical chimney substrates, including brick, concrete, sheet metal and fibre cement. The substrate must be clean, dry and sound. At the junction between the chimney and the roof area, reinforcement fabric is embedded in the waterproofing to provide additional strength at this heavily stressed detail. The waterproofing is taken sufficiently high up the chimney and connected to the roof waterproofing.

The surface of the rubber-based ALLESDICHT waterproofing is resistant to temperatures of up to around 100 °C. With conventional combustion appliances, the external chimney surface generally remains well below this temperature, particularly in the upper section of the chimney. Waterproofing the junction in this area is therefore generally possible without difficulty. The actual surface temperature remains decisive; if in doubt, a chimney sweep can provide guidance.