Why Floors Sag, Bounce and Squeak Over Time

There are many reasons why your floor may start to sag, bounce and squeak. It pays to inspect under the floor, if you have access via a basement or crawlspace. Problems arising from excess moisture, damage from water leaks or pest activity may need to be addressed.

More commonly, over time with dimensional lumber, the timber shrinks because of moisture or aging, which results in a floor that is bowing down or bowing up. Joists that are set at the maximum spanning distance for their weight, must support the extra weight. This stresses the floor joists, which is also a common contributing factor to why your floors may be sagging, bouncing and squeaking.

Here are some check points to consider and investigate before you look for the best strategy to repair your floor.

Check the Condition of Your Floor

Common Causes of Sagging, Bouncing and Squeaking:

·       Aging joists: Over time, wooden supports can bow or weaken and sag.

·       Inadequate support: Joists may be spaced too far apart or are undersized.

·       Foundation settling: Movement in the foundation can cause unevenness.

·       Moisture issues: Excess humidity or water damage can lead to rot.

·       Poor past repairs: Quick fixes may have made things worse.

Use a straightedge, level, or laser level to identify dips and bows to determine how much reinforcement is needed.

Methods to Reinforce the Joists

Option 1: Sister the Joists

This method involves attaching a new joist alongside the existing one to strengthen it. As you read below this can fix the issue but can be costly and time consuming.

How to Sister a Joist:

1.    Cut a new joist to match the existing one.

2.    Apply construction adhesive to the side of the old joist.

3.    Clamp the new joist tightly in place.

4.    Secure with structural screws or carriage bolts.

5.    Use a jack, if needed, to gently lift the old joist level before attaching.

 

This can substantially increase the strength of floor. However, it can also:

1: Be a more costly exercise for materials.

2: Gaining access to subfloor space with structural timber/lumber may not be possible.

3: Getting a full length of new joist into its load bearing position besides existing joist maybe impossible.

 

Option 2: Add Blocking or Bridging

If joists are spaced too far apart, blocking or bridging may help distribute weight more evenly. However, like sister joists this is time consuming and doesn’t always fix the problem, it can actually increase the amount of squeaks and unevenness of the floor

For Blocking:

1.    Cut wood pieces to fit snugly between joists.

2.    Place them every 4–6 feet in straight line.

3.    Nail or screw in place, flush with joist edges.

For Bridging: (sometimes referred as herringbone)

1.    Use 1x3 wood or metal bridging strips.

2.    Install diagonally in an X-pattern between joists.

3.    Fasten securely to minimize movement.

Blocking and Bridging can be a good method but, in my experience, will not achieves desired result for all the effort and money spent with this solution. These methods are usually done at the time of original build.

Option 3: Add Extra Support if Needed

If your floor has significant sagging, consider adding a beam and posts underneath for extra strength.

How to Install a Support Beam:

1.    Raise beam into the desired position (wood or steel) perpendicular to the joists.

2.    Install new post to support the beam and floor above

3.    Anchor it with post supports and secure it to the foundation.

This is especially helpful in older homes with long spans of unsupported flooring and is a great option, however this can also be;

1. Very costly 

2. If the room below is a family room or kitchen, you don’t want a beam and posts to change the floor space.

3. Will need contractors to install correctly.

Option 4: The Adjustable FloorLock System

The good news is that these common issues can easily be fixed without the expense of installing a steal beam under the sagging or bouncing floor space, yet the result is just as effective. And, if you’re a homeowner with a love for DIY, the Adjustable FloorLock Bracing (AFB) has got you covered.

See our DIY Installation Video 🎥  https://www.youtube.com/watch?v=SBOdPpfDjUE

Or read our other Blog Posts, such as:

·      DIY Installation Guide

·      How to Create a Temporary Support

·      Securing End Joist to Outer Wall Frame