Seeley Library at Cambridge University was designed by James Stirling. Completed in 1968, the library won an RIBA Gold Medal in 1970 and has been Listed by English Heritage. The building features an intricate angled glass structure creating a light and airy library with a partial glass roof overlooked by numerous meeting rooms, some of which are cantilevered with viewing galleries looking out across the Library. To afford students total peace and quiet the meeting rooms have been provided with secondary glazing but one room presented a significant challenge due to the many and varied shapes and angles used to create the viewing gallery. The existing glazing is a complex patent glazing roof construction with opposing pitches and multiple hips. The secondary glazing needed to run parallel and Selectaglaze used digital 3D mapping and modelling to perfect a solution that maintained the existing sight lines. The final result is both efficient and aesthetically pleasing. Since this project was completed the Series 30 has been superceeded by the Series 31 lift-out.