Aren't we excluded because of the building's age?

It has been 20 years that I have been a member of group of shareholders for an old building in Texas. I am one of the board directors of the co-op building. The building is 45 years old and has never had a wheelchair ramp. One of our shareholders wants a ramp at the front of the building. Nevertheless, our garage is at the ground level entering the building from there; it requires going up only a very small incline. This has proved satisfactory up until now. One of our directors says Fair Housing Act would require us to accommodate a shareholder if a ramp were requested. Is there such rule like that? Aren't we excluded because of the building's age?