[Solved!] Why Does My Floor Shake When I Walk: 5 Common Causes

Bouncy and spongy floors are rarely a problem. However, there is no serious structural problem underlying the problem. Why does my floor shake when I walk if this is not a serious structural problem?

Generally, when subfloors are nailed instead of installed with wood screws and construction adhesive, they can loosen over time. Consequently, certain types of movement may cause the floor to vibrate.

It is possible to experience vibrations when running a washing machine or walking across a floor with a loose subfloor. Furthermore, homeowners get used to springy floors very quickly. Because of this, most of them are unlikely to consider it seriously. Nevertheless, visitors will notice immediately that your floor is bouncy or shaking when they enter your home.

Resolving the problem requires getting to the root of the problem. Before searching for a solution, it is essential to understand what causes the problem. Although hiring a professional to resolve this issue is recommended, a capable DIY enthusiast can also reduce vibrations by repairing suspect areas themselves.

Read the complete guide below to learn why your floor shakes when you walk.

5 Common causes of bouncy floors

Do you ever wonder what makes your floor bouncy or spongy? The following reasons will help you understand why.

Subfloor Damage Caused by Water

A plywood floor is built out of OSB boards and plywood, and both are secured together with glue. Consequently, long-term exposure to water causes the adhesive to break.

You may experience bouncy floors if you have standing water inside your crawl space or a plumbing problem. According to Low Country Foundation Repair, excess water can cause high humidity levels, which can warp wood, weaken your floor joists, and reduce their load-bearing capabilities.

The presence of moisture stains on the floor can indicate a leak or moisture problem. Inspect the baseboards and lower portions of the wall for stains as well. In most cases, dark discolorations indicate moisture, which leads to mold and mildew. Another sign of mold or mildew is musty odors.

Also See: Can Mold Grow Under Vinyl Plank Flooring? (Answered)

Construction Damage Caused by Snow and Rain

A building’s subfloor, which consists of plywood or OSB board, gets wet during construction. The structural strength of the subfloor is reduced if these materials remain wet for an extended period.

Homes constructed during the monsoon season are more likely to suffer from this issue. In addition to poorly wrapped and roofed houses, the problem is expected to affect poorly insulated homes. 

Also See: Cork vs. Foam Underlayment: Which is Right for Me?

Trusts or Joists That are Cracked

Damaged floor trusts and damaged joists weaken the support that holds the subfloor up. A weakening reduces stiffness but does not eliminate sponginess. The damage is more severe when multiple framing members lie adjacent.

There can be many reasons why cracks form. These implements are usually worn out when they are subjected to excessive weight. There is a possibility that such damage can occur when a building contractor places a heavy pellet of tiles towards the center of the floor.

Termites Might Ruin Floor Trusses or Joists.

It is common for termites to use wood as a source of food, but they also tend to take away the strength of the wood. The phenomenon may continue as long as the wood’s power is not compromised.

Eventually, the floor will flex and appear spongy due to this damage. As soon as possible, this issue should be addressed to prevent the floor from failing.

A Lack of Cross-Bracing or Blocking in Critical Areas

There may be a need to increase blocking and cross-bracing between trusses and joists. The floor load is transferred to the adjacent beam or truss if cross-bracing and blocking are performed. Additionally, it will minimize the bouncy ness or sponginess of the floor. 

A Step-by-Step Guide to Fix Floor Vibrations

The guide below will provide you with the most effective method for resolving the issue of floor shaking. Following the steps may fix your problem permanently. However, hiring an engineer or contractor to handle this job would be advisable. A professional would be able to resolve the issue straightforwardly.

Step 1: Supplies Needed

To complete the DIY process, the first step is collecting all the necessary equipment. Make sure you have every piece of equipment you need before you begin; otherwise, you might end up destroying the entire flooring, which would not be a good thing.

• Ladder
• Measurement tape
• A stud finder
• Crayons for marking
• Dust mask and safety glasses
• Cutting saws or reciprocating saws for drywall
• Framing lumber is 2 by 6 inches
• Handsaw or circular saw
• Connectors for framing, 2-by-3 inches, 90 degrees
• Joist hanger nails of 1 1/4 inches
• A hammer
• Construction adhesive

Step 2: Locate the Problem Area

Repairing a floor begins with identifying areas that need to be repaired. The most simple way to identify vibrations is to mark them if you know where they occur roughly. In order to fix the vibration problem, an assessment of the underfloor will be required after locating the problem area.

In case you cannot find the area that needs to be repaired, run or hop around the area until you hear the vibrations of the floor. Alternatively, you can place a half glass of water on a table, walk or hop on the floor, and see where the water vibrates the most. By doing this, you can determine which part of a room needs to be repaired.

Step 3: Make Sure You Take the Proper Safety Precautions

Make sure you wear safety glasses and a dust mask before starting the DIY project. Install support blocks between the joists by cutting out sections large enough. The spacing between joists should be 16 inches apart, so cut 12-inch wide sections between them.

Step 4: Cut the Blocks Based on Your Measurements

When placing blocks between floor joists, measure the distance between them. When installing blocks between two exposed joists under the first floor, each joist must be marked with a joist number. In the case of larger areas, more blocks are installed. Cut the blocks out of 2-by-6 framing lumber using a circular saw or handsaw.

Step 5: Attach the Framing Connectors

The 6-inch-wide side of each block should be facing up when placed flat. Install framing connectors measuring 2-by-3 inches. Their outside corners must be aligned for the connectors to align with the ends of the blocks.

For attachment to a joist, one of the 4-inch sides should extend upward from the face of the block. Use a hammer to drive one 1/4-inch joist-hanger nail into each machined hole on opposite sides of the connectors and the block faces.

Step 6: Glue the Blocks Together

To ensure a smooth installation, install the blocks one by one between the joists. Using a generous amount of construction adhesive, attach the upper edge of a block to the underside of the subfloor by applying it along one of the 2-inch-wide edges.

Then, with a hammer, drive the lower edge of the block upward, so the upper edge is tight against the subfloor. Use hanger nails to attach each end of a block to each of the 90-degree joint holes in floor joists.

FAQs: Why Does My Floor Shake When I Walk?

To Conclude

Several factors cause spongy floors. Every homeowner should know what they are. By doing so, they can determine if further investigation is needed.

Possibly the floor has become bouncy or spongy on the second story. Upon further inspection, you discover that the first floor’s ceiling, right underneath the problem area, has cracked plaster or damaged plasterboard.

Most homeowners would do little more than monitor the problem if the floor is slightly spongy and there are no other warning signs.

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