Floors and doors

Soft Spots in Your Floor: What They Mean and What to Do

A spongy spot in the floor can be a loose subfloor or hidden water damage. Here's how to find the cause.

A floor that gives a little when you step on it is easy to ignore. But a soft spot in the floor is the house telling you something. Sometimes it's a loose sheet of subfloor. Sometimes it's water damage that's been going on for a while. Here's how to figure out which.

How a Floor Is Built

Most wood-framed floors have three layers:

• Joists: The wood beams running underneath that carry the weight.
• Subfloor: Plywood, OSB or, in older homes, wood planks nailed across the joists.
• Finished flooring: Vinyl, laminate, tile, hardwood or carpet on top.

A soft spot can come from any of these layers.

Common Causes

Water damage

The most common cause we see. Look for soft spots near:

• Toilets (a failed wax ring or slow supply line leak)
• Tubs and showers (bad caulk or grout)
• Kitchen and bathroom sinks
• Dishwashers, washing machines and water heaters
• Exterior doors, where rain blows in under the threshold

Water soaks the subfloor, and over time it delaminates or rots.

Loose or under-fastened subfloor

Subfloor can pull loose from the joists over time. Nails back out, glue fails, and the floor gets a bit of bounce or a squeak.

Gaps between subfloor seams

If two subfloor sheets meet between joists without support underneath, the edges can flex.

Damaged or undersized joists

A cracked, notched or sagging joist makes a bigger area feel bouncy. Plumbers and electricians sometimes cut joists to run pipes and wires, which can weaken them.

Crawl space moisture and pests

In homes with crawl spaces, high humidity can soften wood over time. Termites and other wood-boring pests can also damage joists and subfloor.

How to Check a Soft Spot

1. Mark the area. Walk around and outline the soft area with painter's tape.
2. Look for nearby water sources. Check for stains, loose tiles, peeling vinyl, swollen laminate or musty smells.
3. Check the toilet. If the soft spot is by the toilet, see if the toilet rocks. A rocking toilet can break the wax seal.
4. Look from below. If you have a basement or crawl space you can safely get into, look up at the spot with a flashlight. Look for dark stains, damp wood, mold, crumbly wood, or damage from pests.
5. Probe gently. From below, press a screwdriver into the subfloor and joists. Solid wood resists. Rotted wood is soft.

Crawl space safety

Crawl spaces can have exposed wiring, sharp nails, standing water, pests and poor air. Wear gloves and eye protection, bring a good light, tell someone you're going under, and don't touch any wiring.

What Fixes Look Like

• Loose subfloor: Screwing the subfloor down to the joists from above, or adding blocking from below, often firms it up.
• Unsupported seams: Adding wood blocking under the seam between joists.
• Water-damaged subfloor: Pulling up the finished floor, cutting out the bad subfloor back to solid wood, and putting in new subfloor before replacing the flooring.
• Damaged joists: Sistering (fastening a new board alongside the old joist) can help when damage is limited.

When It's More Than a Handyman Job

Be honest with yourself about what you're seeing. Call the right pro when:

• The leak is in the pipes, not the fixture. If water is coming from supply lines or drains inside the walls or floor, call a licensed plumber.
• Several joists are damaged or the floor is sagging across a room. That's a structural issue. A structural engineer or foundation contractor should look at it.
• You see signs of termites. Call a pest control company first.
• There's a lot of mold. A mold specialist may be needed.

How HLM Can Help

We handle flooring repair, including subfloor repair when the damage is limited, and fixture-level fixes like resetting a leaky toilet with our toilet repair service. If we open up the floor and find more than we should take on, we'll tell you and point you to the right kind of pro.

Many older homes around Hogansville and LaGrange have original plank subfloors and crawl spaces that need extra care. Our guide to older home repairs talks about what to expect. If the soft spot is by a toilet that also runs or wobbles, see running toilet causes.

Get It Checked

Text a photo of the area and tell us where it is in the house. Call or text (706) 594-5049, or use our free estimate form. Pricing depends on the job, and estimates are free.