The new left-hand turning leading from Berkshire Way underneath the railway bridge, and the newly created right-hand lane coming out of Downshire Way onto the roundabout will be closed.
This will be in force for 24 hours a day from tomorrow, Saturday, until Friday, June 6.
Bracknell Forest Council said: “A major high pressure gas main that supplies Bracknell needs to be moved and replaced as part of a series of ongoing improvements at the junction.
“Originally, National Grid assured the council that the work would only require off-peak road works but unexpected engineering difficulties have led to longer closures being needed.”
The council added it had secured an agreement from National Grid - which are carrying out the work - for longer working days to minimise disruption.