Stress-laminated bridge decks in Sweden are usually made of glulam beams of spruce and it is therefore crucial to avoid moisture as the wood has no impregnation that can protect it from decay. Typically the protection of the deck consists of a waterproof bitumen sheet under the asphalt layers on the top surface and of claddings along the edges. The aim of this work was to study the risk of damages and how to ensure the function of the deck plates. The adhesion of bitumen sheets and the effect of different primers was studied. The design at the edges was studied and an improved solution with a steel angle along the deck edge was developed and tested. The improved design should be robust and easy to install to always assure a correct performance. The new design has been developed within the European research project DuraTB - Durable Timber Bridges and is now included in general recommendations for timber bridges in Sweden.