In existent buildings, rising damp is particularly diffi cult to treat, due
to the thickness and heterogeneity of the walls. Traditional methods of dealing
with this problem (chemical or physical barriers, electro-osmosis and so on)
have proved somewhat ineffective. In recent years, numerical and experimental
research into the validation of a new technique: wall base ventilation system, to
reduce the level of rising damp, conducted at the Building Physics Laboratory,
Faculty of Engineering, University of Porto, has yielded interesting results. This
article describes and analyses the results obtained following the implementation
of hygro-regulable wall base ventilation systems in laboratory and in churches in
Portugal. It was defi ned with criterions to avoid condensation problems inside the
system and crystallizations / dissolutions problems at the walls.

• Wall base ventilation system as a new technique to treat rising damp in existent buildings