A total of 50 objections have been made against the proposals for Kepwick House which the developers Benchmark say will offer "magnificent" sea views.
Several residents at the site – which was built in 2008 as part of The Sands development – have complained the proposed expansion is "purely about profit" and disregards those who will be directly impacted.
They also said the "inadequate" site parking already causes problems and that the expansion would lead to more disruption.
One resident said in a letter to Scarborough Borough Council: "It would be unwise to deliberately exacerbate this problem, especially for apartments that are marketed as five-star quality."
Planning permission for three apartments on the roof was previously granted on appeal in 2015, however, these plans never came forward.
The latest proposals for nine penthouses have been recommended for approval by Scarborough Borough Council's planning department ahead of a meeting on Thursday.
In a report to the meeting, a council officer said the design and appearance of the proposed extension is considered to be "acceptable".
The report said: "It is recognised that quite a number of existing residents oppose the scheme and that building an additional storey while it is occupied would cause disruption.
"However, the local planning authority is not able to refuse the application due to this or some of the other concerns raised.
"In respect of other matters falling within the planning domain, including the impact on residential amenity, fire risk and parking, the application has been carefully examined and is considered to satisfy relevant policies and guidelines."