Have 3 trees. One is upright. Other two are collapsing at the top and getting tangled.
It would be hard to say without photos. The problem is likely on the opposite end of growing too fast, though. Usually fungal infections are the cause of trees collapsing, but it can have other factors, such as too much shade, or even down to a lack of silica in the soil.
Please provide some photos, and I will be more than happy to help diagnose your tree.
In the meantime, this article will help you with the care of these trees: https://www.gardeningknowhow.com/ornamental/trees/oak/columnar-oak-trees.htm
We wish to plant a columnar oak, as my husband loves them. The location is about 16 feet from our house. Thank you for any information regarding the root system. Noreen Gibbs
They aren't known for it, but all trees have the potential to harm structures if planted close enough.
16 feet should suffice for foundations and structures. Since these trees aren't expansive above ground, you don't need to worry much about branch drop that far out. As long as you aren't planting close to a septic system or sewer lines, it shouldn't be an issue.
Here is an article that will give you more information on caring for the tree: https://www.gardeningknowhow.com/ornamental/trees/oak/columnar-oak-trees.htm
Here is an article that will give you examples of trees to avoid near structures and lines: https://www.gardeningknowhow.com/ornamental/trees/tgen/trees-with-invasive-roots.htm
My neighbor is notorious for overwatering, and I have a columnar oak that got stunted due to it. I planted two at the same time and the one that is stunted now was by far the better one at time of planting. The other one is now huge--probably at least 30 feet tall. The stunted one has not come out of it yet. I felt like the last couple years it has grown somewhat but then I think it is my imagination. It leafs out every year and seems to have put on some new growth. Will it ever catch up to the other one? I think we have the watering issue solved.
These trees typically grow slowly to moderately. Do you have them both in full sun? A little shade can make a difference.
I would suggest a soil test. There might be something amiss in the soil under the stunted tree. Then you will know what nutrients to supply.