H+R were asked and required to investigate structures at the fascinating Ragged School in North London prior to a large scale planned refurbishment. Originally built in 1841 from charitable funds in order to educate the most destitute of London, this building was reputedly to go on and influence Charles Dickens and his seminal work Oliver Twist. The building featured a remarkable large arch braced truss hall/gymnasium at second floor level.
H+R were appointed to complete multiple packages of investigation on the property. Including investigations of lintel structures, roof finishes and lead work, timber roofs and floors, historic plaster and lath as well as a comprehensive damp evaluation. Floor timbers were also subject to visual strength grading analysis so that a probable strength class could be determined and calculations of loadings achieved by the structural Engineer. An essential exercise when the use of an historic structure alters significantly from a private or civic building to a commercial or corporate one.
How we solved the problem
H+Rs wides range and specialism in material science analysis and condition investigation was utilised to determine the properties construction and condition. Subsequent recommendations could then be made to help inform design decisions. The timber packages included vulnerable and representative timbers being resistance drilled and deep probed to determine the presence of decay and deep moisture contents/risk to further decay. Constructional details such as jointing, service notching, pugging and build-up were noted and marked-up onto CAD drawings. Damp investigations included a comprehensive moisture profiling package whereby masonry samples were taken back to the laboratory and gravimetrically weighed before being heated at a sustained temperature and then weighed again to determine the quantity of hygroscopic moisture and available salt content. A full proof damp package could then be actioned.