I'm looking at a home which will require an addition downstairs. What's the best way to ball-park estimate the impervious cover I can add?

Asked by Chuck, Austin, TX Sun Jan 30, 2011

I realize an engineer is needed for an exact answer, but I'm hoping to find a quick-and-dirty way to estimate by using the survey, local codes and a calculator. I just need a method. thanks

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Les Sherman,…, Agent, Austin, TX
Mon Jan 31, 2011
The quickest and most accurate way, if the property is in Austin, would be to call or go by the planning and zoning office at 505 Barton Springs Road, off of S. 1st St. and Barton Springs and ask for a planner. They can pull up overlays on their computer that will tell you exactly what impervious coverage is allowed on your particular lot and can tell you if there are any specific restrictions within your neighborhood plan, Call 974-2000 and ask for Residential Building or Development Assistance and then ask for a planner.
3 votes
John Crowe, Agent, Austin, TX
Mon Jan 31, 2011
I second Les' recommendation. Try Christopher Johnson – 974-2769.
Web Reference:  http://www.crowehomes.com
1 vote
Pelin Guzel, Agent, Dallas, TX
Mon Jan 31, 2011
I think it is very hard to estimate these important information, If you work with a Realtor, your Realtor will give you the best advice.
Good Luck!
0 votes
James Pounds, Agent, Austin, TX
Mon Jan 31, 2011
Les is right. It will be specific to your zoning -- SF-3, SF-4, etc -- and any amendments to that zoning by your neighborhood group.

Then you can use your survey and a scale to calc what % of total area you currently have, and how much (if any) you can add. Remember, there are two criteria to meet: % of impervious cover AND % of building cover.

James Pounds
Coldwell Banker - United, Westlake
0 votes
Charles Fisk,…, , Austin, TX
Mon Jan 31, 2011
Typically, the total impervious coverage can not exceed 45% of the total lot size of a lot zoned for single family. This area includes the building footprint, driveways and sidewalks. If you are considering an addition in the central city, the McMansion ordinance may affect your addition as well.
0 votes
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