In what way is Henry built like a brick outhouse?

Readers don't get much of an explanation as to why Henry is described as a "brick outhouse." We actually get more narration about his nose than we do his build. The description is a slightly comical and good way to let us know that Henry is big and strong. He's also probably quite square-looking. He's broad-shouldered, and his body doesn't have many curves as it descends toward his feet. His big, strong frame is one of the reasons that the military is happy to have him. He is the kind of soldier who can be given some of the heaviest weapons and ammunition. Readers do get a little piece of information about Henry that tells us he knows he's big and strong. He and Lyman are posing for a picture, and we are told that Henry put his arm around Lyman "very carefully, as though it was heavy for him to lift and he didn't want to bring the weight down all at once." At a different point in the story, we are told of something that illustrates Henry's strength quite nicely. Susy lets down her hair, and Henry easily hoists her up on top of his shoulders so that her hair's full length can be shown.