What is the marriage line on a manufactured home, and why does mine open up?

The marriage line — also called the mating line — is the seam where the two halves of a multi-section home join, and when it opens seasonally the cause is almost never the seam itself. It is the support system under the home. Here is the mechanism, and it is the defining northern-climate defect in manufactured housing. Piers, footings and anchors set above the local frost depth lift every winter as the ground freezes and drop every spring as it thaws. Because the two sections are supported independently, they move independently, and the seam between them opens and closes on an annual cycle. The symptoms buyers describe fit that exactly: doors that stick only in winter, a ceiling seam that gapes in January and closes in June, and cracked drywall running the length of the home along the line. What goes wrong at the line: missing marriage-line piers, which is the usual cause of a sagging seam; the gasket or weatherseal between sections missing, compressed or never installed; the line never sealed in the crawlspace or attic, leaving the two sections open to each other; missing or improperly installed ridge-beam and mating-wall structural connections; and water entry at the ridge, a classic source of long-run interior damage. If your floor is uneven or the seam keeps opening, call us about a manufactured home inspection, or use the free instant quote tool below.