As mentioned earlier, increased insulation standards necessitate the need for careful moisture management in the structure of buildings. Our Synergie Sd Variable membrane has the ability to change its water vapour performance (Sd value), ie. the membrane becomes more diffusion open depending on the relative humidity (RH) in the area surrounding the membrane. In the colder, winter months, the micropores of the membrane stay diffusion tight, preventing vapour from the warm interior of the building diffusing into the timber roof/wall structure or insulated layer. However, in the summer drying out months, the micropores of the membrane open, allowing any vapour/moisture trapped in the insulated material to escape back into the building interior and dry out/ventilate naturally. In the long run, over a few years, this ability to act as a barrier in winter and a breathable membrane in summer, helps to protect the building from structural damage caused by excessive moisture trapped in the building fabric.
The Synergie Sd Variable membrane is ideally suited to flat roof make-ups which are not adequately ventilated or diffusion tight towards the outside. The Sd Variable membrane is also suitable in new build where excessive moisture accumulation has occurred during the initial construction phase of the building process where timber elements and/or thermal insulation has suffered an unplanned wetting.
Synergie Sd 2/100 Vapour Control Layer
The Synergie Sd2 100 Membrane, with its optimum fixed Sd value, Sd2, is suitable for the underside of ceilings in most pitched roof applications, where breathable roofing membranes (with typical Sd values of Sd 0.02) are incorporated, as they are diffusion open to the outside. The Sd2 vapour control membrane allows for an ideal level of vapour control. The rule of thumb is that the Sd Value of the Internal membrane needs to be a minimum six times higher than the Sd Value of the External roofing membrane.