Trees are planted around my house for shading from the intense Texas sun. Since the house is on a small lot, the distances between trees and the foundation are 10'-15' (varies).

I remember reading that the roots are as wide as the tree. Does it mean if I diligently keep the tree trimmed (height and width), roots will be off the foundation?

Mature trees I have are possomhaw holly, Mexican pistachio, cherry laurel, fragrant honeysuckle, and rusty Blackhaw. I also have young Texas mountain laurel, evergreen sumac, crape myrtle, nandina, and yaupon holly. Thank you.

The premise that roots extend to about the ends of a tree's branches is a myth. Roots are opportunists; they grow where they get water, nutrients and where they can survive. Trees in the wild often will have roots extending twice the height of the tree or even more.

However, planted trees in yards may tend to have a relatively more compact root spread, because trees are sparsely planted (compared to a forest) and favorable conditions for root growth is lessened. They may tend to stay near to the tree canopy because of the shade it provides, keeping the ground cooler (and more moist) so roots can survive better. But no, they aren't "confined" to the tree's canopy spread, and trimming branches on one side won't stop their growth on that side.

Trimming the tree to keep it small, however, will correspondingly reduce the need for a large root system. I'm not too familiar with the trees you have and their ultimate size, as I am in the northern USA. If a tree wants to grow big, it's pretty hard to stop it.

Most of those sound like 'large shrubs' or multitrunked trees.
Crepe myrtle can get huge, but it depends on variety.

I think you'll just need to watch for problems, but not assume you will have them, or where. From what Luis said, I'd keep any irrigation away from the house (if not already doing that).

You have to water all sides of the tree or you may end up with one dead side. I don't think any of the trees on your list are known for cracking foundations.

My trees are all small and mostly native trees, and I am keeping them small. But your notes remind me of the foundation irrigation I have all around the house (because of expansive clay soil). Your notes tell me that the irrigation will attract roots, and I cannot win over the roots by just trimming the top.

Thank you. My conclusion: Once the trunk becomes big, I have to replace the tree with a younger plant.

10' is plenty far away for any of your trees. The biggest one is likely the Crepe Myrtle and they only need 4'. I've seen big ones in a 2' planter cutout in a sidewalk with no lifting issues.
The natives won't need any additional irrigation either.

I understand that crape myrtles are considered safe to plant near foundations. It is certainly done regularly around here where watering foundations is also recommended.

Rupertlee said: My conclusion: Once the trunk becomes big, I have to replace the tree with a younger plant.

None of the trees you mentioned will crack the foundation of your house.

Lucy68 said: None of the trees you mentioned will crack the foundation of your house.

Thank you. I feel safer and can enjoy the shades the trees provide.