I purchased a house built in 1960 and like other people have mentioned the terrible bounce, I got the same exact situation.

I'm thinking of installing blocking to strengthen the floor. The 7 joists are spaced 14½ However, since they're all buckled at the lower part of the joist, ranging from 14⅛ - 14⅞ I wanted to know if it's safe to wedge between 14½ blocks forcing them to move back that extra space. (see below picture)

I also so wanted to know if this load sharing would cause to much weight on other parts of floor beams.

enter image description here

  • It looks like you have 2x12’s (1 5/8” x 11 5/8”) floor joists at 16” on center. Can you confirm this? AND what is the span of these joists (face of support to face of support).
    – Lee Sam
    Dec 10, 2018 at 2:15
  • It's 2x10 spaced 15 in I don't understand the the rest of what you're asking me to check
    – Joseph Wit
    Dec 10, 2018 at 3:03
  • What is the distance the 2x10’s span from support to support? (I’m guessing it’s about 16 feet or so?)
    – Lee Sam
    Dec 10, 2018 at 3:11
  • Yup it's 16 feet
    – Joseph Wit
    Dec 10, 2018 at 3:30
  • I reconstructed my question and concern
    – Joseph Wit
    Dec 17, 2018 at 5:28

1 Answer 1


Bouncy floors are caused from too much deflection in the floor. Too much deflection is caused by “undersized” floor joists for the load and span.

Depending on the species and grade of your floor joists, they should only span about 14’-15’ or so. When your five year old runs across the floor it “pounds” (impacts) the floor supports. Because the floor joists are already overloaded, those little feet can cause the bouncy floor problem.

To correct the situation, you’ll need to 1) increase the size of the joists or 2) decrease the span.

  1. You can increase the size of your supports by adding a “sister joist” or adding a joist between each existing joist.

  2. You can decreas the span by adding a support beam under the joists with new footings, etc.

It’s complicated and expensive. But the good news: When he turns into a teenager, that bouncy floor will seem trivial.

  • Are any of the three options going to work for my floor see link below
    – Joseph Wit
    Dec 10, 2018 at 18:18
  • I’ve never heard of adding bridging to solve deflection problems. I doubt if it works, but I like the third option: add a support to decrease the span.
    – Lee Sam
    Dec 10, 2018 at 19:56
  • Can I use this Simpson Strong-Tie 22-Gauge Tension Bridging
    – Joseph Wit
    Dec 13, 2018 at 19:27
  • Or this 3/4 in. x 10 ft. Galvanized Steel Hanger Strap
    – Joseph Wit
    Dec 13, 2018 at 19:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.