You could build an entire village of log cabins with how many times they're referenced in "Shiloh," even though, as Norma Jean points out to Leroy, "They won't let you build a log cabin in any of the new subdivisions" (1.7). While it's clear throughout the story that Norma Jean isn't interested in living in a log cabin, Leroy has trouble giving up on the idea. When he's at a loss for what to do or say next, he tends to fall back on this fixed notion of building Norma Jean a home.
For Leroy, building a log house from a kit is an extension of his obsession with building other types of useless things from kits, which in a way represents his past—his childhood, to be specific—when little boys build make-believe structures out of blocks and…Lincoln Logs. That's how his preparations are described, in fact, as playing:
Leroy plays with his log house plans, practicing with a set of Lincoln Logs (5.9).
Leroy's log cabin symbolizes the importance of the idea of home for him, but at the same time, it's an unrealistic fantasy and another sign of his lack of maturity.
Mabel keeps bugging Leroy and Norma Jean to visit Shiloh because it's "so full of history" (5.30). You'd think that someone so taken with history would be on board with Leroy's idea to build a log cabin, right? Wrong. For Mabel, living in a log cabin isn't a fantasy as it is for Leroy; it was her reality:
You couldn't get me in a log cabin . . . I was raised in one, It's no picnic, let me tell you (5.15).
For Mabel, a log cabin symbolizes a negative image of home. It's a place of hardship, and she has absolutely no nostalgia for living in one.
Mabel tells Leroy and Norma Jean about "a log cabin at Shiloh" that "was there during the battle. There's bullet holes in it" (5.28). When Leroy and Norma Jean finally go to Shiloh, they drive past "the log cabin Mabel mentioned. It is surrounded by tourists looking for bullet holes" (7.1).
"That's not the kind of log house I've got in mind," says Leroy apologetically (7.2). Of course it's not. Leroy envisioned a log cabin that would provide a solid home for him and his wife—a place of safety and security.
By contrast, this log cabin got caught in the crossfire of the Civil War. It symbolizes the destruction of Leroy's home life. It's shortly after they see the log cabin that Norma Jean tells him that she plans to leave him, shooting all sorts of holes in his plans to build her a home. As he tries to come to terms with her bombshell, he has an epiphany:
He sees that building a log house is the dumbest idea he could have had. It was clumsy of him to think Norma Jean would want a log house. It was a crazy idea (7.30).
Sadly, this realization comes too late to save his marriage, and soon after, Norma Jean flies the coop—for real this time.