Building work on a new £2.2m refectory at Wisbech Grammar School is set to start on Monday.
The project, which is being carried out by RG Carter, is expected to be completed by January 2015.
Access to the site for the company's vehicles will be via Barton Road and not North Brink.
Headmaster Nicholas Hammond said: 'Whilst we will endeavour to ensure as little disruption to traffic flow around this area of Wisbech as possible, there could be some. We hope to minimise inconvenience.'
The new dining block will offer panoramic views of Wisbech Grammar School's 25-acre site, which was bequeathed by the Peckover family to establish the girls' high school more than a century ago. The present dining hall will be converted into a library.
Mr Hammond said: 'This is an exciting development for the school. It is affirming our confidence in the school and enhancing our facilities here.
'It links very nicely with the expansion in terms of our fields.'
He added the mix of buildings on the site reflected the school's individuality and its evolving history. The new refectory would allow members of the school community, as well as visitors, to appreciate the grounds in which the school is set.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here