Does anyone know the city's ruling on Impervious Coverage limits on remodels? (Austin: house)

[EnvisionMan]

I am trying to find out how the city handles remodels of older homes that exceed the 45% impervious coverage. I have been asked to help with the design of a remodel on a home that was built in the 60's. At first glance it appears the property is probably 60% to 70% covered with the house and stone pavers. It is a very hilly lot, and there are a lot of stone walls creating terraces (those walls count towards impervious). The front courtyard area is a huge motorcourt with garages on both sides... all paved.

The owners do not want to add anything to the impervious, but they want to add to the height of the house (turning some of the house from a 1-story to a 2-story). Since we are already over the 45% impervious, will the city allow things to stay the same? I cannot find where this is addressed on the city ordinance site.

Any help/guidance would be appreciated. Thanks!

[bridgebats]

There's the impervious cover, but there's also the floor-to-area ratio which limits the size of the house compared to the size of the lot. So, a two story home with 1000 sqft on each floor counts as 2000 sqft. Of course, this is only applies to a certain area of Austin. Also, does this hilly lot include any greenbelt? Many of the hilly lots are actually 1/3 acre+ because they include green space.

Before they changed the city's website, I could have easily found the link, but I can't seem to find it again. I suggest searching for the "McMansion Ordinance" and heading down to speak with them in person. They have worksheets available for you to calculate the limits of the buildings.