Taking possession of a Texas rat snake (Pantherophis obselota lindheimeri) is much easier than acquiring appropriate housing for one. A number of approaches to caging will work, as long as you provide enough space the proper furnishings. Airflow, temperature regulation and security are crucial factors.
Snakes are excellent escape artists. If your enclosure isn't 100 percent escape-proof, you will eventually come to feed an empty cage. Most commercially produced snake cages are well-designed to prohibit snake escape. Cages with bypass glass doors are usually escape-proof for all but the smallest captive snakes. If young children will be present, include locks to prevent unauthorized access. Multipurpose aquariums with aftermarket or custom-built lids deserve extra scrutiny but can be made secure. Lidless rack systems such as those that professional breeders use are secure but are not feasible for most hobbyists.
Many keepers and breeders suggest that snakes become stressed in large cages, but this is not necessarily true. While snakes do spend extended periods of time curled up in small hiding spaces, they still need to be able to exercise, stretch out and thermoregulate. Zoo standards state that a cage must be tall enough to accommodate an irregular branch for climbing and that the minimum perimeter for the cage should be 1 1/2 times the length of the snake. An adult Texas rat snake of 6 feet, as such, needs a cage with a perimeter or circumference of at least 9 feet.
Texas rat snakes require ventilation, but not a lot of it, which would affect humidity and temperature adversely. The proper airflow strategy depends on cage type. In most cases, commercially produced cages or aquariums with screened lids will have adequate ventilation. As long as your snake isn't showing signs of dehydration or bad shedding, ventilation is likely appropriate. Reduce ventilation by using acrylic or plastic pieces to cover portions of the screen.
A Texas rat snake prefers temperatures that vary between 65 and 90 degrees Fahrenheit -- he needs some hot and some not-so-hot. Provide it with a basking spot created by a heat lamp, heat pad or radiant heat panel, at one end of the enclosure. With a temperature gradient between the two ends of the habitat, the snake can access a preferred temperature at any time. Ensure the temperature at the basking spot stays around 90 degrees Fahrenheit, and ensure that the temperature in the habitat falls the farther away from the heat source you go.
Furnishing the habitat is an important part of caring for Texas rat snakes. A hide box is imperative; two are preferred, one placed at each end of the thermal gradient. Hide boxes should barely fit the snake; the top of the hide box should touch the snake's back when the snake is inside. In addition to a large water dish, include an irregular branch or two for climbing. Texas rat snakes are avid climbers. Use aspen shavings, cypress mulch or newspaper as substrate.