About & Contact

Lyons O'Neill /

Sweethaws Wood /

This one off house in its beautiful woodland setting required a 15m clear span at lower ground floor level as well as thin floor plates and board marked concrete finishes. The 15m clear span at lower ground floor level was achieved by designing part of the steel frame as a two-storey vierendeel truss. As well as providing floor-to-ceiling openings to the upper floors on the same elevation the frame allowed us to kept the floor zones within the required 200mm structural depth. A 3m wide verandah was also achieved using a series of stainless-steel tension rods, supported from high-level steel beams cantilevering over the vierendeel truss. This use of rods built in tolerance which allowed us to adjust the level of the exposed edge.


As the movement of the frame during construction was key to providing a straight elevation, predicted deflections were generated for each node of the frame which were monitored at salient points as the structure was loaded. Construction sequence sketches were produced at RIBA Stage 3 forming part of the tender documentation, illustrating the importance of the sequence and the stages at which deflection would be monitored.







Lyons O'Neill is a young company whose experience is grounded in some of the country's premier design-led practices. Our experience, both on site and in the design office allows us to approach each problem from both practical and theoretical view points.


We aim to identify the key issues or elements within a project at an early stage. Whether these issues are of a technical nature or Client/ Architect led, we strive to draw these out to develop the structural hierarchy.


The ability to draw and illustrate problems remains central to our design process. Sketching both design issues and building processes, enables us to both record and communicate key structural design decisions throughout the project.



5 Maidstone Mews

72-76 Borough High Street

London, SE1 1GN


tel 020 7223 7222

email info@lyonsoneill.co.uk



London Blackfriars Station, the Worlds largest solar bridge with 4,400 photovoltaic panels covering the roof of the station