Buildings must withstand moisture – pay close attention to old buildings

Structures and materials need to be more moisture tolerant than ever. It pays to be vigilant in the case of old moisture engineering solutions in particular.

The waterproofing of residential wet rooms has markedly improved over the last couple of decades, and for good reason: wet rooms are now under much more pressure than a few decades ago.

“Moisture control is at a good level in the construction of new wet rooms," says Juha Vinha, Professor of Building Physics at the University of Tampere.

“More effort has been put into various structural solutions and working methods, training and certification have been developed, and their implementation is closely monitored,” he adds.

However, precision is particularly important when planning a wet room for an old building.

"For example, if you want a wet room built within cellar walls bordered by earth in an old building, it is worth paying attention to the humidity loads to which the structure is subjected from various directions, and to drying solutions," Vinha says.

When renovating old structures, it is also worth taking note of the risks associated with additional thermal insulation. Since internal thermal insulation weakens moisture control, it should be installed externally when possible. This makes conditions within an old structure drier and warmer. If internal thermal insulation is used, it should be thin in order to avoid over-cooling the old structure, while using sufficiently tight vapour and air barriers to prevent moisture in indoor air from condensing on the old building’s interior structures.