Water on the fascia board or on the façade below the gutter does not always come from a leaking gutter system. The cause may be the arrangement of flashings at the eaves. Gutter aprons are intended to direct water into the gutter, but they must work together with the covering and the underlay. None of these elements works in isolation from the others. It is worth starting the inspection by establishing where the water actually flows. Most of the water runs off the outer surface of the covering. Moisture conveyed by the underlay may also appear beneath the metal sheet. Both routes must be taken into account in the eaves detail. How they connect to the gutter or are led out beyond the protective layer depends on the chosen solution.

Stains on the north wall do not point to a single cause. Water may come from a leak, the ground or humid air in the room. Less sunlight makes drying more difficult and encourages cooler surfaces. Before choosing insulation, establish the source of the problem. Covering the stain with a board may only hide further dampness. Observe the connection between the stains and rain and wind direction. Check gutters, flashings, window sills and cracks in the façade. A mark under the window may result from a leaking detail. Dampness at the floor may require an assessment of the insulation at ground level. However, the shape of the stain alone does not give a reliable diagnosis.