The National Trust has applied to the Lake District National Park Authority for consent to place a rail on steps at the 18th century Bridge House.
The trust said the rail would allow safe access to the first floor of the Grade One listed building and preserve its cultural heritage.
But Michael Johnson, clerk to Lakes Parish Council, which has unanimously recommended the plan for refusal, disagreed.
“We strongly oppose anything that will disturb this ancient building,” he said. “If they were to put this adornment up it would be sacrilege.
“The building has been there all these years without the requirement for this health and safety. I am quite sure it could be dealt with by a discreet sign.”
Built in 1723 by the Braithwaite family, Bridge House has been used as a counting house, an apple shop, a tea room, a weaving shop, a cobblers, a chair makers and, at one time, a home to a family of eight.
Straddling Stock Beck, thousands of tourists have flocked from all over the world to to see it while artists such as John Ruskin, William Turner and Kurt Schwitters have drawn inspiration from its quirkiness.
In 1926 it was bought by a group of local people for £425 and passed into the care of the National Trust in 1928.
Fiona Green, who is leading the project for the trust, said: “We’d like to be able to reflect those different periods of its history, which we know people are very interested in, but without imposing too much on the building’s natural characteristics.
“The installation of a handrail will mean people can safely visit the upstairs and quietly reflect on how a space can adapt and change, while remaining a special place.”
But Harry Manning, chairman of Ambleside Civic Trust, said the appeal of the historic house was its exterior.
“The importance of Bridge House is its visual appearance not making it into an indoor tourist attraction,” he said.
The plan, likely to go before planners next month, has received support from the Society for the Protection of Ancient Buildings.