Bouncy, Sagging Floors in an Older Home: What's Underneath

Most of what people call a foundation problem looks different depending on how the house was built. A slab house sits on concrete poured right on the ground. When a slab settles, you see cracks in the concrete, gaps at the baseboards and doors that stick, but the floor itself rarely feels soft.

A pier and beam house is built differently. Wood beams run across short piers in the crawl space, joists sit on the beams, and the subfloor sits on the joists. Every one of those parts can move a little on its own. That is why a pier and beam floor can feel bouncy or springy in one room and solid in the next. It is also why these houses are usually easier to bring back to level than people expect, because there is room to get underneath and work.

Plenty of older homes in our area were built this way. Census figures put the median year built for homes in Warrensburg at 1986 and in Holden at 1967 (Census Reporter, ACS table B25035). The houses near the downtown square and the older streets around UCM are a good deal older than that median, and a lot of them have a crawl space under at least part of the house.

We see the same few causes over and over. Usually more than one is at work.

Piers settling in wet clay. The soils across Johnson, Pettis and Henry Counties have a lot of clay in them. Clay swells in a wet spring and shrinks hard in a dry August. A pier sitting on clay that stays wet will slowly sink, and a pier on clay that dries and pulls away loses support. Either way, the beam above it drops and the floor follows.

Shims working loose. Between the top of a pier and the bottom of the beam there are usually wood or steel shims that hold everything tight. As the ground moves through the seasons, those shims can crack, shift or fall out. A beam with nothing pressing up on it will flex every time someone walks over it. That is the bounce you feel.

Rot at the sills, beams and joists. Wood that stays damp for years softens and loses strength. The first places to go are usually where wood touches masonry or sits close to wet ground: the sill plate along the outside wall, beam ends, and joists near a plumbing leak or a low spot where water collects. Soft wood sags even when the pier under it has not moved at all.

Spans that were always too long. Some older homes were framed with beams spanning farther than they should, or with piers spaced wide apart. Those floors may have had a little give from day one, and decades of moisture make it worse.

Almost every one of those causes traces back to water. Roof water dumped at the foundation, a yard that slopes toward the house, a crawl space vent that lets humid summer air settle on cool wood, or a slow leak under a bathroom. The clay under the piers stays wet, the wood above it stays damp, and the house slowly settles into it.

If the crawl space smells musty, or you can see standing water or white fuzz on the joists, start with our post on crawl space moisture in Missouri homes. It covers where that moisture comes from and how to tell when it is a real problem.

We fix the water first. Leveling a floor without dealing with the water that let it drop means doing the job twice.

Every house is a little different, but a repair on our pier and beam adjustment jobs follows the same four steps.

1. Inspect the crawl space. We measure how far the floor has moved and find which piers have settled, shifted or failed.
2. Lift the frame back toward level. Jacks raise the beams gradually so the floor above comes up without stressing the finishes in the rooms.
3. Replace or add piers. Failed piers are replaced, new ones are added where spans are too long, and everything is re-shimmed tight.
4. Repair the wood and the water. Rotted beams and joists are repaired, and we correct the drainage or ventilation that caused the moisture.

All of the work happens in the crawl space. You do not need to move out, and the only sign inside is a floor that is level again and doors that close the way they used to. A job like this usually takes one to three days, depending on how many piers are involved and how much wood needs replacing.

If the crawl space itself is damp, the floor repair holds up better when the space is dried out too. That can mean fixing the drainage, sealing the ground with a heavy vapor barrier and supporting weak framing, which is what our crawl space repair and encapsulation work covers.

Not every soft spot is an emergency, and we will tell you straight when it is not. A little give in an old floor, with no change you can measure over a season, no sticking doors and a dry crawl space, is often something to watch rather than fix right away.

Here is a simple way to keep an eye on it at home:

• Set a marble or a level in the same spot every few months and note what it does.
• Mark the top corners of any door that has started to stick, and see whether the gap keeps changing.
• Take a flashlight to the crawl space access after a heavy rain and look for standing water or damp soil.
• Watch for new cracks in drywall above doors and windows, or gaps opening between the floor and the baseboard.

If nothing changes and the crawl space stays dry, there is usually time to plan. If the floor keeps dropping, the cracks keep growing, or you find water down there, that is the time to have it looked at.

We cannot tell you what is happening under your house from a blog post, and nobody can tell you from a photo either. These are the signs that mean it is worth having someone crawl under and measure:

• A floor that has gotten noticeably bouncier or more sloped over the last year.
• Doors and windows that stick in one part of the house and not another.
• Leaning piers, loose or missing shims, or a beam that visibly dips between supports.
• Soft or crumbly wood at the sill plate or beam ends when you press on it.
• A musty smell that does not go away, or standing water in the crawl space.

When we come out, we measure the floor, look at the piers and framing in the crawl space, and trace where the water is coming from. Then you get a written scope and price. Nothing to sign on the spot, and no trip charge anywhere on our route through Warrensburg, Knob Noster, Sedalia, Clinton, Holden, Windsor and the farms in between. If the floor can wait, we will say so.

Floor feeling bouncy? Request a free inspection or call (816) 718-3385 and we will come take a look underneath.