Lime Street Station opened in August 1836 as a replacement for Liverpool & Manchester Railway's 1830 Crown Street Station. The original roof at Lime Street was formed of timber trusses on iron columns and arcades. An extension to Lime Street was authorised in 1832, engineered by George Stephenson assisted by Thomas Gooch, with alignment corrections by Joseph Locke.

The original roof was replaced in 1848. The new one (now gone) spanned 153ft 6in and was 374ft long. It cost £15,000, covered six tracks, three platforms and a roadway, and was designed by Locke, then Chief Engineer of the London & North Western Railway. The roof had 17 curved wrought iron trusses at 21ft 6in centres supported on one side by station buildings and on the other by cast iron columns. It was clad in wrought iron corrugated sheets and glass. The design was checked by William Fairbairn and John Kennedy, the contractor was Richard Turner of Hammersmith Iron Works, Dublin, and load testing on two bays was carried out by Locke.

In 1867-68 the station was lengthened in the direction of Manchester and widened. The northern-most bay of the roof that can be seen today was built at this time. Its engineer, William Baker, was then Chief Engineer of the L&NWR. The southern bay was added seven years later and is also by Baker.

The roofs are 645ft long, curved, tapering and cover most of the platform area. The spans of the north roof vary between 185ft and 215ft, with an average of 212ft. The spans of the south roof vary from 170ft to 195ft wide.

The structure of the roofs is similar. They have splayed trusses at 32ft centres, supported on walls at one side and on 20ft high cast iron columns in the centre of the station, which they share. The trusses are 44ft 9in in total height, 22ft 9in in depth and have a rise of 22ft. Their top chords are 'I' sections and the bottom chords are 6in x 1in plates. They use angle iron struts in a similar pattern to that of a Warren girder.

Research: PD