H+R were instructed to undertake detailed timber condition investigations of large trussed lantern roof structures forming part of an historic market. Following on from these surveys, and working alongside a conservation accredited engineer, we were to produce a Contractor Design Portion submission (CDP) ‘palette’ of remedial repair details that could be applied throughout all eight of the lantern roofs, where decayed timber interfaced with sound timber.
Initially H+R undertook detailed timber condition surveys of all the lantern roofs so as to determine the extent of timber decay and identify similar defects that could be included in the CDP palette of repairs. Concurrently, accurate measurements of representative elements including the full trusses to enable modelling using CAD software. Lengths of decay, moisture content readings, residual cross-section, and dimensions were all taken during the survey, with decayed timber elements spray painted for easy identification
How we solved the problem
After collating the condition survey data, it was decided that a total of seven remedial repair details were required to encompass all the areas and types of decay affecting the trusses and the associated timbers. These were drawn up in CAD as construction drawings, and accompanied by supporting structural calculations. These were subsequently passed to the Principal Contractor for review and implementation.