Why East Valley Mobile Homes Go Out of Level After Monsoon Season

September 4, 2026

Every October the same call comes in from Apache Junction, east Mesa, and Gold Canyon: the doors stuck while we were gone. The home was fine in April. Nothing hit it. And now a door drags, the hallway has a lean, and on a doublewide the ceiling seam has opened a hair. The cause is under the floor, and it is the monsoon. A relevel fixes it for $450 to $800 on a singlewide or park model and $750 to $1,400 on a doublewide, takes a day, and the level check that tells you exactly what moved is free. Here is what actually happens under a home between June 15 and September 30, and why the desert, which is better ground than most of the country, still moves.

Start with the good news about the ground

A manufactured home carries its whole weight through a few dozen pier footings, each about a square foot, and under the East Valley those footings press into some of the best natural bearing ground in the United States.

The USDA soil survey of the eastern Maricopa and northern Pinal counties area describes the fans and terraces between Mesa and the Superstitions as deep, well-drained calcareous loams and gravelly sandy loams. The Laveen soils the survey says most of Mesa sits on are loam with more than 15 percent lime to 60 inches. On the terraces and the mountain-front fans, the Pinal and Cavelt series carry an indurated lime-cemented hardpan, caliche, at 4 to 20 inches, and the survey rates permeability through it as very slow. Dense, dry, lime-cemented alluvium does not compact and migrate under a pier the way Florida sand does. That is why a home set properly here goes many years between relevels, not three to five.

So why did the doors stick?

Reason one: the lot was never prepared

Most of the park stock along Apache Trail, US-60, and Main Street went in decades ago on ground that was raked flat. Arizona’s installation rules today require a home site to drain half an inch per foot for ten feet away from the home, and the soil under the home to be crowned so water runs out, not in. The state’s own installation FAQ still exempts park lots from the crowning requirement. On a lot like that, a monsoon burst puts water on the pads and it stays there until it soaks in or evaporates.

The soil survey’s descriptions tell you what happens next. On the sandy Antho ground the survey maps northeast of Mesa, and names as home sites, water moving through the sand under a concentrated load takes sand with it. On the gravelly loam above a hardpan, the water cannot go down through the pan, so the loose layer above it stays saturated for days, and a pad on it settles as it drains. On the excessively drained gravelly sand of the wash margins, the survey’s Alluvial land association, a running wash simply relocates the ground.

The NOAA 1991 to 2020 normals for the Apache Junction 5 NE station put 12.55 inches of rain a year at the foot of the mountains, 3.94 of it in July through September. That does not sound like much until you see how it arrives.

Reason two: the rain comes all at once

On July 28, 2022, the National Weather Service recorded one to three inches of rain in one to two hours on the Superstition and Goldfield Mountains. All of it ran downhill into Apache Junction. Weekes Wash and the other washes came out of their banks, inundated crossroads, closed and damaged roads across the city, and swept a car half a mile downstream before it caught on a box culvert. The city’s three watersheds, Weekes Wash at 8,021 acres, Siphon Draw at 27,632, and the Roosevelt Canal at 35,868, drain the mountain front straight through the neighborhoods and parks.

A pad that spends an hour under moving water comes out lower. A pad that spends a day under standing water on an ungraded lot comes out lower too, just more slowly. Multiply that by the eight or ten storm days a typical monsoon delivers and the quarter inch of settling at one end of the home is not mysterious.

Reason three: clay in the subsoil

Not all of the East Valley is sand and caliche. The survey maps the Mohall-Contine association, loams over clay-loam subsoils, across 29 percent of its area, mostly the flat old fans the subdivisions and many parks sit on. Clay loam swells when it is wet and shrinks when it dries. A pad on it rises a little in a wet winter, drops a little in June, and never quite comes back to where it was. The survey is blunt about the extreme case: on one clay soil in the area, Cashion, large cracks developed in the walls of homes built on it because of its high shrink-swell potential. A manufactured home on piers does not crack that way; its piers walk instead, a little each cycle, and the doors report it.

Reason four: heat on the shims

This one has nothing to do with rain. Between the pier cap and the steel beam, a manufactured home sits on hardwood shims: nominal 4 by 6 by 1 inch, in pairs, driven tight, no more than one inch of them, with a hardwood plate or a solid block filling any gap beyond that. That is the federal standard at 24 CFR 3285.304, and it is what a proper relevel installs.

Wood shrinks as it dries. The July normal high is 105.2 at Apache Junction 5 NE and 105.9 at east Mesa, and the crawl space under a home with the skirting closed and the vents blocked is hotter than the air outside. Four months of that dries and checks the shims and the lumber caps. A shim that was driven tight in March has clearance in September. A pier that has clearance is carrying nothing, and the piers beside it are carrying its share. Under the older park units, where the “shims” are a stack of scrap plywood and cedar that has been drying since the 1980s, this is often the whole story.

Reason five: nobody was home

A door that starts rubbing in July gets noticed in July if someone is living there. In this town the home is empty. The City of Apache Junction’s winter visitor survey estimated about 50,000 seasonal residents in town November through March, and the resorts empty out in April. The settling that would have been a phone call in July is a sticking door, a slack strap, a peeled skirting panel, and a rat in the belly by October, all at once.

What the fix involves

A relevel is a measured process, not a jack and a guess. The crew shoots every pier with a water level off a datum pier so the frame’s actual shape is a set of numbers before anything moves. Twenty-ton bottle jacks on solid cribbing lift the low sections in small increments at several stations, so the chassis returns to plane as a unit and the drywall stays put. Each low pier gets rebuilt to tight contact with fresh paired hardwood shims inside the federal allowance; any pier that cannot reach the beam inside that allowance is rebuilt at the right height, not stacked taller. The frame is re-shot to verify, the marriage line on a doublewide is confirmed closed, and the anchor straps, which went slack when the home settled, are re-tensioned. The full walkthrough is on the mobile home leveling page.

Most post-monsoon calls land in the base relevel range and finish in a day. Homes that have gone many summers without a check usually add some pier and pad work, priced per pier on the written survey. The pricing page has everything.

How to slow it down

The relevel fixes the elevation. It does not change the ground, and it does not stop next summer’s storms. Three things stretch the interval on this ground, and the survey report flags which ones apply to your lot:

• Move the water. A swale, a downspout extension, a regraded strip along the low side. Arizona’s half-inch-per-foot drainage rule is the target even where the park never met it.
• Vent the crawl space. Skirting vents open and clear so the ground under the home dries after a storm instead of steaming under a closed lid. Closed skirting on a wet lot is the worst of both.
• Fix the pads, not the shims. Where the survey finds a pad sunk into soft ground or sitting on the loose layer above the pan, rebuilding that pier on a proper pad, cut down to the hardpan where it is reachable, is the fix that lasts. Reshimming it is the fix that is back next October.

And check the straps. Every settlement leaves them slack, and the monsoon outflow that comes off the Superstitions at 55 to 65 mph in a normal event, and past 100 in the bad ones, is the wind the anchor system exists for. Arizona requires every mobile and manufactured home to have one.

The bottom line

The desert is good ground, and a home set right on it stays put for a long time. The homes that go out of level after the monsoon are the ones on lots that hold water, on sand or clay the survey mapped decades ago, or on shims that have been drying since the Reagan administration, and they go out of level while nobody is home to notice. The level check is free, it is the right first call the week you get back, and it comes back with a pier-by-pier map and a firm number instead of a pitch. Crews cover Apache Junction, Gold Canyon, east Mesa, San Tan Valley, and Florence.