The Grantham based firm said it expects to reduce its workforce by 65 hourly-paid workers and 20 salaried staff which represents a 50% fall in staff numbers.
Bell & Webster has been working on three prison-building projects that are due for completion by the end of the year, but has suffered a reduction in orders because future prison-building projects have been stopped.
A spokesman told the Grantham Journal: “I can confirm that we are reducing the current workforce to match the current projected workload.
“Three custodial projects will have been completed by the end of this year and the company has a greatly reduced forward workload for the coming months.
“The forward workload means that the company has proposed to reduce 85 direct employees.
“These reductions will not affect the company’s ability to deliver current and future projects and mean it will be well positioned for the upturn in hotel and student accommodation markets.”
The company has entered a period of consultation with the GMB union and non-union staff.
GMB regional organiser Sian McClarence said the company intends to stagger the redundancies and that all 85 will take place within three months.