Sash Windows Northumberland Sash windows are one of the best features of any property as they stand out in a positive way and add value to any home. Over time they lose their ability to perform to high standards and start to let more and more noise through. The primary features of letting the light in and not allowing the heat to escape can also be affected by aged windows. David Humble offers sash window renovation services that are a much cheaper alternative to replacement, that will give you the same incredible results. He is pleased to offer services to the whole of Northumberland, Tyne and Wear and County Durham.