Weep holes are drainage holes left in the exterior wall of a cavity wall construction to allow water that has entered the cavity to freely drain back outside. To reduce the visual impact, minimise the entry risk of large nest building insects and remove the risk of unwanted pointing to a fully open perpendicular joint, it has been an industry norm to install proprietary wall weep ducts. Cavity wall weeps are to be installed at regular linear intervals in a masonry wall to allow drainage above ground level and fitted within dpc cavity trays in areas where a cavity has been bridged. Cavity wall weeps are positioned in perpendicular joints and bedded in mortar.