Modular Home Button-up Procedures

Some customers hire a general contractor who is unfamiliar with the correct modular home button-up procedures. Other customers take on the challenge themselves with even less experience, since they’ve never built any kind of home before.

What Can Happen When Your Contractors Don’t Know the Correct Modular Home Button-Up Procedures

One of my customers, who hired an independent GC, called me four years after he moved into his home. He’d found a bulging drywall seam in the vaulted foyer of his two-story modular home. A carpenter friend of his had already fixed the seam three years in a row, but it had reappeared that winter. He wanted to know what was wrong with his home.

Cross section detail showing the modular home button-up procedures for joining the two floors of a vaulted foyer
Illustration A shows the modular home button-up procedures for joining the two stories of a vaulted foyer when the second-story floor joists sit directly on the first-story ceiling joists. Illustration B shows the modular home button-up procedures when the floor joists are spaced several inches above the ceiling joists.

When we removed the drywall at our inspection, we found a ¼” gap between the framing of the first-story ceiling and the second-story floor. The GC had failed to put any shims into the gap. This meant there was nothing to stop the modules from moving up and down in the winter when the heat was drying the framing out or in the summer when the humidity was causing the framing to expand. Since my customer completed his previous repairs to the foyer in the summer when the wood had already expanded, it was not surprising that the problem reoccurred in the winter when the materials were shrinking. As the second-story floor pressed down on the first-story ceiling, it buckled the band of drywall. Drywall is too brittle to resist that kind of compression. We explained to the customer what the correct procedure was and even helped him complete some of the work. When I spoke to him the following spring, he was very happy to report that the problem had not reappeared.
If you hire an independent GC without prior modular experience, make sure he is learns the correct modular home button-up procedures. Your dealer should be able to help with his education.
For more information about modular home button-up procedures, see Selecting a General Contractor and The General Contractor’s Responsibilities for Building a Modular Home in my book The Modular Home.