Ask Mr. Smarty Plants

Mr. Smarty Plants is a bit confused. In the first sentence you tell me you are “building a house where the HOA requires two live oaks in the front yard.” In the next sentence you say that “The trees are large and one is already touching the house----”. This sounds to me like the house is already built, and the oak trees are already planted. Then you ask “How far apart should these live oaks be planted---?”

Never the less, I will try to provide you with some information to answer your questions.

The Texas Tree Planting Guide  is an interactive guide that has lots of information and is fun to use.  From the guide we learn that the live oak Quercus virginiana (Coastal live oak)  is considered a large tree with a mature height of 40 to 80 feet, and approximately the same width. The minimum space requirement would be 180 square ft. Trees should be no closer that 40 to 50 ft. The roots are going to extend out from the trunk to reach the drip line at least, and perhaps even farther.
This guide from the Houston Parks and Recreation Department  recommends  that a tree this size should be no closer than 15 - 20 ft to a structure.

Since you are planting live oaks in Harris county, I am including several links about oak wilt that you and your HOA should be aware of.

Texas Forest Service

Natural Resources Conservation Service

Texas Forest Service

I’m suggesting that given the situation you describe, Live Oaks may not be the tree for you. To look for other possibilities, lets go to our Native Plant Data Base.

Scroll down to our Recommend Species Lists and click on View Recommend Species page. Click on Central Texas on the map, and you will get a list of 156 commercially available native plant species suitable for planned landscapes in Central Texas. This is too many for now, so go to the Narrow Your Search box on the right side of the screen and select Texas under State, tree under Habit, and perennial under Duration. Check sun under Light requirement and dry under Soil moisture. Click on the Narrow your Search button, and you will get a  list of 19 native trees for Texas landscapes. Clicking  on the scientific name of each plant will bring up its NPIN page which contains a description of the plant, its growth characteristics and requirements, and in most cases images. As you check out each plant, you can note its size and other features.

Hopefully, using this and the Texas Tree Planting Guide, you can find a tree that you and your HOA can agree on.