Land hunting can be a daunting experience. There are myriads of considerations ranging from school districts, commute times, views to construction feasibility, codes, exposure and more. Purchasing a property is a huge investment and it is important that you understand what you can do with the land once you have entered into that contract. Every city and county have individual requirements, restrictions and codes – a licensed professional can help you look into the codes in your area, this entry looks at Austin, Texas and residential construction in particular. The concepts can be quite complicated so we have decided to break this post up into a series with the following entries: Part I – Setbacks, Part II – McMansion , FAR & Impervious Coverages, Part III – Overlay districts & Zoning. Licensed Architects can help you understand how to make your dream home plausible while navigating through this maze but hopefully these entries will help you understand what all is involved in a residential feasibility study for a lot purchase. To see more about working with an architect see this post.
Part I: Setbacks
Most city jurisdictions have prescribed lot setbacks where construction is not permitted. In Austin the typical setbacks for a typical lot are 5′ from the side yard property lines, 10′ from the rear property line and roughly 25′ from the front. In Austin the front yard setback is actually determined by averaging the distance of 5 closest houses from the front property line, if none exist then 25′ is used. If the lot is a corner, fronting two streets the city requires a 15′ side yard setback from the side yard that fronts the street. Typically, corner lots are larger anyway.
Another setback that is particular to Austin and can sneak up on people is due to a tree ordinance that is in place to protect old growth trees. While large trees can be considered an amenity for many reasons, if that beautiful tree is smack in the middle of the lot, it may make the lot very difficult to build on. Tree’s that are “protected” are defined as a tree over 19″ in diameter measured at 4’6″ above ground. The setback limits what you can do within a foot of radius per inch of tree diameter. Yes it is slightly confusing, let me break this down some with an example, if a tree is 24″ in diameter then the “Critical Root Zone” (CRZ) is 24′. The CRZ is the area that must be protected during construction and more importantly the city will not permit you to excavate more than 4″ within 50% of this area (the 50%CRZ) for our 24″ diameter tree example this would mean that no excavation can take place within 12′ of the tree. Pier and beam construction is generally the way to go when large trees are in the area and steel structure can help cantilever the structure over the CRZ if required. In addition to the roots the city protects the canopy – the ordinance does not permit you to cut more than 30% of the tree’s canopy. Any requests for an exception for a tree between the sizes of 24″-28″ can be handled with the city administratively. If you need to request an exception involving a tree that is over 28″ in diameter the city requires that you partake in a public hearing. See the city’s page for further information here.
Another setback to be aware of is a National Electric Code requirement. The NEC requires a 7′-6″ setback from electrical lines. This is measured from the center of the pole and is a required setback nationally. This only applies to overhead lines.
Please note that in Austin, there are overlay districts that have different setback requirements, the above setbacks are typical but are not the only setbacks in place currently.