Soft or bouncy floor: a lost pier, or a wet subfloor

A floor that gives underfoot is one of the two things people notice first in a settled manufactured home, the other being a door that has started to stick. It has two very different causes and they feel the same from above.

The two causes

A lost pier. The floor over that spot is no longer being supported. The footing pressed into wet ground, or on the clay side of the county the ground shrank away from under it in a dry summer, the pier went slack, the load it was carrying moved to the neighboring piers, and the floor between them flexes. You feel it as a springy patch in one area.

A wet subfloor. Water has reached the decking from a torn underbelly, a plumbing leak, or a roof leak. The state’s own installation rule describes the result: water build-up leads to “delamination of floor decking.” This one feels spongy rather than springy, and it keeps getting worse in the same spot.

Often both. A torn belly lets water at the ground under the piers as well as at the subfloor, so one water problem produces both symptoms.

If the home is a site-built pier-and-beam house, a soft floor is usually a sagged or rotted joist rather than a block pier, and the house leveling page covers that.

Narrowing it down from inside

1. Walk the area and map it. One spot between two points, or a whole strip along one side of the room?
2. Do the marble test in three rooms. Consistent direction everywhere means the frame is low on that side. One room going its own way points at a local pier or a soft patch.
3. Press it hard and listen. Springy with bounce-back tends to be support. Spongy, with the vinyl or laminate feeling detached, tends to be decking.
4. Look for water clues. Staining, a musty smell, cupped flooring, a tub or toilet nearby, a ceiling stain above.
5. Check nearby doors. Sticking doors in the same area point at frame movement. See doors and windows sticking.

Then look underneath, or have somebody look, because that is where the answer is.

What we look for from below

Under a lost pier: a visible gap between the cap and the I-beam, a leaning or cracked block, a footing pressed into the soil, or a pier you can rattle by hand. A pier you can move is carrying nothing, and its load went to the pier next door, which is how failures spread.

Under a wet subfloor: a torn, sagging, or missing underbelly, insulation hanging down, staining on the decking, damp material, and often signs of animals, because a torn belly is an invitation.

Why homes do this here

Where the home sits in Hidalgo County decides which version you are likely to have.

On the loam uplands around Edinburg, north McAllen, and north Mission, the ground is Hidalgo sandy clay loam, well drained and low in shrink-swell. Piers there lose bearing when the crawl floods. The June 2018 storm put 18.31 inches on a gauge west of Mission and an estimated 2,700 homes and businesses in Mission and McAllen took water; Hanna in July 2020 dropped 14.40 inches northwest of Mission and left 18 inches to four feet standing east of Edinburg. A footing on ground that wet presses in, and the soft floor shows up months later after the water is forgotten.

South of Business 83, under Pharr, Alamo, San Juan, Donna, and Weslaco, the ground is Harlingen, Mercedes, Raymondville, and Runn clay. Harlingen clay runs 60 to 75 percent clay and its cracks stay open 150 to 210 days a year. When it shrinks through a 99.6-degree August it pulls away from under a footing, and when September’s 4.61 inches arrives it swells back, but not evenly. A pier on that ground can be carrying nothing in summer and everything in fall. The soft spot comes and goes with it.

Both kinds of ground put water against the belly when they flood, which is why the wet-subfloor version follows every big storm year. The water under the home page covers that side.

Do not jack it yourself

A bottle jack under a soft spot loads the frame in a place that may not be designed to carry a point load, and lifting one point on a home that is already out of level pushes stress into walls, plumbing, and the chassis. Cracked drywall and broken drain lines are the common outcomes; a slipped jack under an occupied home is the uncommon one.

In Texas this is licensed installation work: Occupations Code section 1201.003(13) puts “supporting, blocking, leveling” inside the definition of installation, and the installer licensing page covers how to verify a licence before anyone puts a jack under your home.

What it costs

Published on the pricing page, and the cost calculator prices leveling work from those numbers.

While somebody is under there

A lost pier means the home has moved, and a home that has moved has slack anchor straps. Re-tensioning is included with a relevel. If the belly is open for a subfloor repair, that is the moment to replace the vapor retarder section rather than patch around it.

What to expect on the call

Where the soft area is, how big it is, whether it is getting worse, whether there is any water history nearby, what the marble test showed, and whether any doors have started sticking. The level check is free and includes getting underneath, which is where this question actually gets answered.

We cover Edinburg, McAllen, Mission, Pharr, San Juan, Alamo, Donna, and Weslaco.