Our home is 8 months old. As time goes on we notice more of a bounce and vibration in our floor. I know there is something known as deflection but could it be more than that. Our floor is engineered with 11 7/8 I joist 16"OC. On our floor plans it states that the length from support beam is 20' 7 1/2" on one end of our floor. It actually measures 20' 10 1/2". This is where our kitchen is and everything rattles when you walk through my kitchen. Current flooring is vinyl flooring. On the other end of the house where the living room and bedrooms are the span is 20' 10 1/2" and should be 20' 5 1/2". When my kids run across the floor my TV shakes in the entertainment center. The floor is L480. It has a live load 40psf and dead load of 10psf.

On the engineered floor layout from the company that designed the floor it states that the floor is not designed for brittle floor finish like ceramic tile and wood. I have tried to get answers from our builder and local building office. The only answer I get it meets code. I have talked to the company where the joists are made and they are within there measurements by 1". Is this common practice or am I just stuck with a bouncy floor? If I want to add support to this floor how do I do that? Any help would be great.

Leah

Is the underside of the joist covered? You may be able to improve the situation by adding X bracing between the joist.

The underside is unfinished. Our builder said X bracing will only cause squeaks and since it meets code they don't have to come look at the problem. We are in the process of trying to find a good framer to frame 2 bedrooms under our kitchen to see it that will help in that part of the house.

If interior walls are constructed up tight against the joist that will help. I don't see how X bracing could cause squeeking (builders will say ANYTHING). If you watch the bottom rail I think you will see it move slightly to one side. Since the top rail can't get shorter and the bottom rail can't get longer something has to move for the I joist to flex. The top rail can't move because its attached to the flooring so the bottom rail moves to the side slightly. The builder didn't do it because he wasn't made to. Doesn't mean you can't. Not likely to eliminate the problem completely but should improve it.

Hi Leah. The skinny on any floor joist is its rigidity of what it can handle in compression and lateral deflection. When either one of those are not is sync then the bounce effect will/can occur.

Quick history in home building, many homes in the 50s actually used 2x8 joist 16"oc. The undersizing of the joist were compensates by running a 3/4x4 tongue and groove " sub-floor at a 45 degree angel. What this changes in floor load "reaction" is its transferring that impact load to a sister joist further away from where you step and not directly to the joist beside the one you are stepping on, using a that joist that has Little load on it. The bottom of the joist were tied together with metal strapping, and many times wood cross bracing between the joist. Newer homes in the 70s etc had 2x10 joist 16" oc with 3/4 tongue and grove perpendicular to joist. The also were crossed braced between joist to stop lateral deflection. Now we got the basics out of the way.

I think you have a couple of problems going on. One is the sub floor is not glued to the top of the I joist with construction adhesive. The "Squeak". The joist will "rattle" easier ans shake more because its lacking full contact with the sub-floor. ( no adhesive) ( Not a gusset effect ) The "Up to specks may very well be true except the inspector can't and won't see if the liquid nail construction adhesive was used on laying down the sub-floor. I joist are less forgiving and actually more ridged then standard wood joist. The "Bounce effect.. When the gusset effect is lost in the I design then its a semi floating sub-floor on very ridged joist.

The other situation is the joists lower lateral deflection. This is normally solved by X braces between the joist. In your case I would go the extra and use 2x6s laid flat under the joist at a 45 degree angel. The 5" added span to the specks won't change the floors rigidity all that much

This is the physical science on any floor joist long or short, metal or wood. Its not an opinion. I could get deep on it but it gets boring..

Hi,Iam cap girls hubby.Sorry you are having trouble w/your new house. I have worked on a lot of older homes where the construction was post and beam. Where the span allowed for too much "bounce" we simply added more posts and/or beams. This is sometimes easier said than done. There is no reason you cannot have tile floors throughout your home. Perhaps your builder/contractor can clarify why this solution has not been proposed. Give me a shout back w/their answer:)

My builder flatly refuses to look at the problem and states it is deflection in his refusal email. I have so much bounce my pictures on the walls in the kitchen move. I have been in more homes that this builder has done recently and we were showed one home and it didn't bounce.

I have hired a structural engineer to come in and give us a true fix to this problem. I was looking on the plans and they state the span will be one length but it is actually longer when they built it. Is this normal to do? Do inspectors actual measure or follow the specs?

I am going to ask the building inspector to come and look at our home because if it meets code, then they need to see what code actually is and how it feels. Do inspectors come back out and look again? My vinyl in my bathroom has actually pulled away from my tube 1/4" and won't hold a seal. Normal?

Thanks for all you imput.

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Do inspectors actual measure

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Not too much unless it's a clearance for a boiler or hand rails steps. They really don't get into the structural plans and measure. They should but miss a lot there.

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am going to ask the building inspector to come and look at our home because if it meets code

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This situation isn't a "code" thing necessarily. The inspectors realize on the architect to do the loads and engineering BUT if it wasn't followed that's a different thing all together. There is where an inspector can miss it.

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I have hired a structural engineer to come in and give us a true fix to this problem.

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That's the perfect step here and then you have the numbers. I'm sure he will pick on the cross bracing and other things.

Get back and let us know how it went

21 boat,
Can you tell me what this means? This EWP system has NOT been designed to carry interior roof loads of any kind, For a brittle floor finish and for any unique or special present or future loading condition.

I'm not sure what all this means.

Can I suggest for the framing of the walls in the basement if you are going to go that route
To strengthen the floor have the framer run the top plate and bottom plate and "stick" frame the wall that means cutting each stud to fit it's the only way to get a tight fit for support

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This EWP system has NOT been designed to carry interior roof loads of any kind, For a brittle floor finish and for any unique or special present or future loading condition.

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What that basically means is it's a light floor when it comes to any dead loads as opposed to live loads. A dead load is a bearing load. Live is temporary loads. Walking etc.

In other words any load bearing (dead load) on that floor is to be transferred in and thorough the floor to by pass the floor itself to carry the load called upon for structural support other then what the "Floor" was intended for its specked use. A "Floor" to walk on period

Here's the general specks on that flooring system
Nordic EWP Floor Construction Details - Bowers Lumber & Components, LLC.

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Originally Posted by Leah4

Our home is 8 months old. As time goes on we notice more of a bounce and vibration in our floor. I know there is something known as deflection but could it be more than that. Our floor is engineered with 11 7/8 I joist 16"OC. On our floor plans it states that the length from support beam is 20' 7 1/2" on one end of our floor. It actually measures 20' 10 1/2". This is where our kitchen is and everything rattles when you walk through my kitchen. Current flooring is vinyl flooring. On the other end of the house where the living room and bedrooms are the span is 20' 10 1/2" and should be 20' 5 1/2". When my kids run across the floor my TV shakes in the entertainment center. The floor is L480.

Leah

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L/480 is the minimum code required floor stiffness. If your floors are designed to this then you have the worst floor that code will allow you to build. I don't think your 12" joists should be spanning more than 12 to 16 feet. For Boise Cascade BCI 5000 I joists, the span tables for the 4 star rated system (L/980 I believe) is < 12'.

Following the code minimums will yield hallways that feel narrow, noisy drains, and as you have learned, bouncy floors. The up side to following the code required minimums is that you have lower construction costs than if you would if choosing to exceed the minimums.

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Originally Posted by Zeaos

L/480 is the minimum code required floor stiffness. If your floors are designed to this then you have the worst floor that code will allow you to build. I don't think your 12" joists should be spanning more than 12 to 16 feet. For Boise Cascade BCI 5000 i joists, the span tables for the 4 star rated system (L/980 i believe) is < 12'.

Following the code minimums will yeild hallways that feel narrow, noisy drains, and as you have learned, bouncy floors. The up side to following the code required minimums is that you have lower construction costs than if you would if choosing to exceed the minimums.

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One more thing: To explain the term deflection- The L/480 is the length of the joist divided by 480 and will give you the amount of deflection in inches. For your 20 foot span, this would be 12'*12 = 240"/480 = 1/2" deflection. This is the amount your floor will deflect (how much it will sag under load). With multiple spans it can create an uplift force on the other side of the intermediate bearing. Kind of like a teeter-totter.

Leah,

Hi I am a contractor in Oregon. I have read your questions and the related solutions that have been offered and I agree that your floor system is NOT built to code. There is no way that such a floor system can meet code and rattle your pictures as you walk across it. The span of the joist maybe close enough to "code" but the other consideration is how far apart these joists are. Your floor joists can span a greater distance by having more floor joists closer together. For example if you have your joists closer together say 12" apart versus 16" apart will make a huge difference on how your floor feels. Your contractor may have gotten the right lengths, but did not verify the correct spacing as manufacturers do require certain spacings to make various spans.

Some states require a builder to have a home warranty with each new home that is built. This is primarily because there is always some settling that occurs with in the first year of a home. Here are a few of my recommendations for what they are worth: 1) Do not try to fix the problem at this point! 2) Contact the lumber supplier who delivered the floor joists to your home and request that the factory rep from the manufacturer contact you to inspect your job. Trust me they do not want bad press. He or she will evaluate the situation and be more than happy to document the problem for you. Now that you have the factory rep's evaluation, you can now proceed with getting the solution solved. 3) Attempt to contact the contractor once more and if he fails to respond, then you have rights and you need to talk with your state's contractor licensing board. They will set up an arbitration meeting with your builder and you can then explain to both the builder and the contractor board what the rep has said. 4) If at this point your builder still does not respond to correct the problem you will have the contractors board on your side. They will either issue a judgement against him and force him to fix the issue or submit a claim with his contractors insurance policy to have someone else fix it.

Now if you did not hire a licensed contractor, your only recourse to seek legal advice from an attorney and getting a judgement in your favor may be a little more difficult and you got what you paid for. Hope this helps.

Bryan

So I have the same problem. I see this is about a year old so I'm hoping to find out what was done to fix it. My contractor did my one year walk through, told me things would get fix and then never returned. So I want to fix it myself. What was done to fix your floor?