A local architect says the city's new rule that high-rise buildings downtown can't be any taller than the Niagara Escarpment is flawed and absurd.

Bill Curran of Thier+Curran Architetcs Inc. in a letter to council is urging councillors to drop the rule when it comes up for ratification at city council tonight.

The letter reflects the position of the Hamilton and Burlington Society of Architects (HBSA), which has argued against the height restriction, saying building heights should be determined by design criteria.

While Curran sent the letter on the letterhead of the society, it says the contents reflect Curran's views and should be attributed only to him.

CBC is seeking comment from Curran.

If approved, the new rules limiting height come into effect in June.

"This seems an absurd requirement, added late in the process with little consideration or consultation," the letter reads.

"We do not see the world in two dimensions as the staff explanatory diagram shows, we see the world in 3 dimensional 'perspective,' which means that objects that are farther away appear much smaller and closer to the horizon.

"As such one and two storey houses obstruct views of the Escarpment. This planning 'principle' is based on a flawed view analysis."

Essentially, the letter says, smaller buildings that exist downtown already "appear" to be higher than the top of the escarpment due to perspective.

With this in mind, a three-storey building that stands right in front of a person in downtown Hamilton could appear to dwarf the much larger Escarpment in the distance.

It says it also has concerns about a lack of research on existing and proposed views in the city, and on if taller pre-existing buildings have had any impact.

It also says this proposal is "unclear, unwieldy," and will create many disputes among planners and the city. It also argues it will have an impact on taxes.

"This latest requirement, if approved, will further unnecessarily restrict appropriate height and density, and thereby walkability, affordability, sustainability and tax assessment," the letter reads.

The new downtown secondary plan, approved by city council's planning committee last week, says that at the lowest elevations designated for taller buildings, high rises can only be about 30 stories tall.

Hamilton has no current rule around this. In fact, three downtown buildings standing right now — Landmark Place, the Stelco tower and the Olympia apartments building — would be too tall to fit those criteria.

"We heard loud and clear from Hamiltonians that the escarpment was the height limit they perceived to be appropriate," said Alissa Mahood, senior program manager, last week.

Limiting buildings to escarpment height keeps lake views intact, she said. And the city can meet its targets for building up the downtown without taller buildings.

It's also not unusual to use a natural feature in this way, Mahood said. In Halifax, planning rules prevent buildings from blocking views of the harbour. Montreal uses Mount Royal as a height limit.