Underneath the sloped roof next to the side window in the ridge of our house het schuin wasps have found a proper place to built their nest. Assumedly they are German wasps (Vesupula germanica)  judging on the increased presence of hunting and foraging specimen of this species in the garden.
They collect wood pulp to convert into paper for nest construction. They find this on the older bee hotel nest blocks and on fences like this female. She uses her mandibles to gnaw the top layer from the wood and returns to the nest with the collected material rolled up into a ball between her jaws and legs.
References1 Nederlands Soortenregister