17-19 High Street, Grantham: a disused building turned into nine apartments

The brief

An empty town centre building with nine homes inside it

17-19 High Street sits in the middle of Grantham, in the South Kesteven district. It was a disused building with a shop frontage and no residential use, and the scheme was to turn it into nine bright new apartments plus a pharmacy at street level. Probus Construction Ltd took the main contract and AJB Group took the entire carpentry package.

Conversions of this kind are harder than new build. There is no level datum you can trust, no square corner you can rely on, and every partition, joist and door lining has to be set out against a structure that was built for something else entirely. The carpentry package is also unusually broad, because it covers everything from the structural floors to the kitchen doors.

Phase one put the team on site for six weeks. The full package was scoped from the outset as:

• New external sash windows and doors
• New shop front windows and hoarding
• 72 internal fire doors and frames
• Two double winder staircases
• New internal joists and flooring
• Stud work partitions to all external walls
• Stud work layout for nine apartments
• Nine kitchens
• One pharmacy shop fit-out

What we did

Structure first: joists, studs and thermal walls

The building had to be given a sense of structure before it could be given a layout. That meant new internal joists and flooring throughout, stud work partitions to all external walls, and the stud work layout that defines all nine apartments. By April 2026 eight of the nine flats were formed, with internal and external thermal walls built around steels, and ceiling works run in between.

The window frontage and the half moon

One flat took a full timber window frontage, with a unique half moon window worked into the composition. AJB Group supplied the timber windows, provided the crane and did the lift itself, bright and early in Grantham town centre. Crane, carpenters and timber windows under one roof is what gives a client a single point of contact through a build rather than three suppliers pointing at each other.

72 fire doors

The 72 internal fire doors and frames arrived in a programmed 9am delivery ahead of the install, which then ran across the nine flats as a scheduled operation. Seventy two doors is not a job you improvise: each leaf has to go to the right opening, with the right frame, the right intumescent detail and the right ironmongery, and the schedule has to be tracked door by door or the fire strategy for the building does not hold up at handover.

Staircases, second fix and kitchens

Two double winder staircases were built into the scheme, which is how you fit a compliant flight into a narrow town centre footprint. Behind the doors came second fix carpentry and nine kitchens, starting in June, plus the pharmacy shop fit-out at ground level.