The current invention relate to a ventilation valve, comprising a main body with passage that extends through with means for attaching the main body to a ventilation opening of structure; a base with means for attaching to the base to the main body at a distance to the main body such that an airflow passage extends between them; and an airflow controller to vary the airflow through the airflow passage. The ventilation valve also comprises a cover to prevent access to the exterior side. The cover is detachably connected to the base so that the relative position between the airflow controller and the base is adjusted while the base is attached to the main body. The base is detachably connected to the main body, so that the base and airflow controller is removed from the main body while they are held in place in the relative position between the airflow controller and the base.