On 30 April Soane sent to Richards 15 working drawings for the house, including plans of the attic, the roof over the garrets, and the roof over the attic, as well as two sections of the roof, drawings of the paritions, and a plan and section of the flues (Journal N^o3). The set did not include drawings for the ground floor, suggesting that this part of the building was already completed.

Drawings 67 and 68 show the first and attic storeys of the house. Drawing 61 is for the first floor masonry and the arrangement of the flues, as well as the timber partitions between rooms. Each timber partition is numbered; some of these partitions are shown in section in drawings 69 to 74. Drawing 68 is of the ceiling timbers for the attic floor. Lanterns are included over the best staircase and the principal corridor (referred to as the tribune in Soane's drawings).

The versos of drawing 67, 68, and 72 show copies of a section through the house, with rough alterations showing a developing design for the tribune. The most preliminary design is on the verso of 72, and drawings 67 and 68 have variations, with Soane's rough pen alterations on drawing 68 dated January 1796. Soane's drawing shows alterations to the ceilings and the internal first-floor windows. The ground floor has a pendentive ceiling flanked by barrel-vaulted alcoves and the first floor has apsidal alcoves flanking the top-lit space and leading to narrow corridors lined with niches for displaying statues. By this time the building was already under construction and alterations had to be made to the built fabric. See drawings 97 to 99 and 106 to 109 for more tribune designs.

Drawings 69 and 74 correspond to drawing 68, showing the partitions in the first and attic storeys. These drawings are copies of those sent to the clerk of works, Mr Richards, at Tyringham for the roof construction. Drawing 70 shows the partitions near the skylight of the best staircase. The partitions are numbered 15 and 14. Partitions 2, 3 and 13 are shown in drawings 72 to 74.

The slates for the roof were delivered in September 1795, although on 29 September 1795 Mr Praed writes to Soane that the Slater has not yet arrived (drawing 104).