When we take the leaky wet areas into account there has been a stand out underlying factor. Timber framed substrates make up approx. 70% of failed wet areas over concrete slabs. Timber frames are built to allow the house to move without failing but this constant movement leaves the screeds to cracking the frame is not engineered enough to have a solid platform (balcony or shower) sit on them and withstand the constant micro movements of the frame below. What do you think of the below suggestions: Should spacing in the frame be reduced to as little as 200mm centers for wet areas? Should we use pond liners that are not fixed to the substrate for waterproofing so that when the substrate moves it does not negatively impact the waterproofing integrity of the balcony? Have another idea please share?