Why Clay Soil Shows Up on Guadalupe County Roofs
In northwestern Guadalupe County the Houston Black clay opens cracks a half inch to four inches wide at a foot down, and in most years those cracks stay open for 90 to 150 days. That one soil fact explains a lot of our calls here. A house that rides that shrink-swell cycle through enough summers ends up with sticking doors, drywall cracks and a roofline that no longer sits flat, so a roof call here often turns out to be a question about the ground too.
The county covers 713 square miles of flat to rolling ground. The northwest corner, where Schertz and Cibolo sit, is Blackland Prairie on that dark calcareous clay. The southeast runs to fine sandy loam, which drains better but still moves. When we inspect a roof on Guadalupe County clay, we look for that pattern, because a shifted frame opens flashing and ridge lines the same way it opens drywall. If the frame is still moving, we tell you and suggest a foundation specialist before the re-roof, so the new roof isn't fighting the house.










