The Old Castletown Road will shut near the Nunnery next month.
The route will be shut from 9.30am until 3.30pm on Friday, May 24.
It's as workers fell large dead Ash trees near the main gates of the facility.
Ramsey company Manx Roots, which is doing the work, says it needs to close the road because the work couldn't be done safely with traffic controls.
Car falls down steep bank on Mountain Road
Panic over - Mcdonald's reopens at 11am tomorrow
Police say beat it to cars illegally parked during MJ tribute act
No dedicated prostate cancer screening programme, despite over 1,200 referrals
Minister says GP waiting times have improved, but delays still impact A&E
Crash closes section of the Mountain Road
Island's prison nears full capacity
Beach hut owner praises youngsters for owning up to break-in