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Noisy 2nd floor

I'm in a 3-yr-old, 2-storey, 3200 sq ft house. 2 bath, 5 bedrooms/office upstairs. Hallway runs down most of middle of second floor. In Spring/Summer, when my wife and I are downstairs for several hours, or when we first get up in the morning, the wall in hallway makes huge noise, like a sharp cracking sound (i.e. not the more common subfloor "creaking" sound. Once we walk down the hallway, no more sounds, but returns as soon as nobody is walking around. Builder has been very helpful, although unless he's here in early morning or late evening, he hasn't been able to really hear the problem.

I don't think this is a load-bearing wall, even though it runs perpendiular to the attack joists. Builder has pulled carpeting and added screws to subfloor, and even doubled up the floor joists below the master bedroom (thinking, at that time that the problem was subfloor/joist movement). He also drove several wooden wedges under floor sill of the wall in question.

It appears to us to be a settling problem, with the wall acting as a large drum head, broadcasting movement between the floor and the wall or floor sill. We've had a building engineer look at this as well, but so far, no progress.

Could the wall be installed improperly, i.e. under too much pressure between the attic floor joists and the second floor? So that in Spring/Summer when the wood expands, the noise returns (this seems to definitely be related to temperature - we live in Boise, ID, were outside temps this past winter have been in the 20-40 range and now, with noise returning, moving up to 50-65. The key, I think, is that once we walk around the "settled" wall/floor, and as long as someone is walking around upstairs, the problem goes away. But once we go downstairs for awhile, it returns. Let me know what other info you need, but if anyone can solve this for us, we going to give you the key to Boise! Many thanks in advance for your suggestions.

Re: Noisy 2nd floor

I give it a try....

The load sharp cracking sound you hear definately indicates frame movement.

Based on the newness of the home it's likely the builder used engineered roof truses.
There is a phenomenom that can occur with these trusses which is well documented with builders across North America and has been labeled as "Truss Uplift".... although the cause is subject to speculation.

There are plenty of discussions between builders and suppliers regarding "Truss Uplift" .... here's the short of the long.

Truss uplift is a fairly recent discovery since modern homes are mainly built using pre-manufactured web trusses for the roof system. Usually the effects can be noises and/or gaps between the partition wall drywall and the ceiling drywall. Typically this gap will open and close with seasonal changes to the outside temperature.

There is still speculation as to the the cause of truss uplift and the actual mechanics are not fully known .... but it is believed to be due to the design of the trusses.

Modern trusses are designed to incorporate triangular webs that are built with dimensional lumber held together with metal plates. Using the properties of the wood , these triangles create very strong structural components which minimizes the overall weight of the trusses.

The most current and widely accepted theory is ...... the temperature and humidity changes in the attic during the winter months affect different sections of the truss differently.

The area of the truss above the insulation will be subject to different temperature and humidity levels than the bottom cord buried deep in the insulation. This difference causes the upper cords of the truss to expand and contract in the cool winter while the bottom cord remains fairly static. This results in an upward bowing of the bottom cord because it is securely connected to the top cords.

The result of this differential movement is the center section of the bottom cord moves upward pulling on the interior wall or simply separating the the drywall and leaving gaps where they join at the ceiling.

If the top plate of the wall is securely fastened to the truss it can raise and lower the entire wall during this movement of the truss. In this case you may experience the loud cracking or popping noise as the framing moves.

Here is a link :http://www.rushwood.ca/trussuplifting.html

Hopefully this makes sense and helps.:)

Re: Noisy 2nd floor

Canuck, Thanks very much for your reply and great information! What a coincidence that you sent the reply because what motivated me to make this posting was the "Ask This Old House" column in the latest TOH magazine (with your picture on page 116!).

I think you've given me what I need to go back to the builder, who is very helpful, but so far unable to find a fix. Now, I'll show him the info on Truss Uplift and I hope it's not to late to make repairs.

We haven't had any separation that I can see between the ceiling drywall and wall drywall, but this certainly sounds like our problem, i.e. no visible cracking, but a loud and definite cracking sound, at the subfloor-to-floor plate point, which radiates throughout the wall.

Many thanks again, and I'll let you know what happens after talking with the builder. This has been driving us crazy, and is so severe that it will create a real issue whenever we sell the house, so it has to be fixed.

If you feel like sending contact info to my Yahoo address ([email protected]) I'd like to send you something from Boise as a small token of our appreciation for your help. If you saw the 2007 Fiesta Bowl where our Boise State U Broncos gave us one of the best college games ever, maybe you'd like something from BSU.


Brian T.

Re: Noisy 2nd floor

Brian ... you're welcome and I hope it helps to resolve the issue.

Please do keep us updated ... the feedback is appreciated. :)

Re: Noisy 2nd floor


A follow-up posting, prior to meeting with my builder next week: the insulation that is in my attic, above the wall in question is about 16" thick, covering the bottom chord splice of the truss (ref your illustration), so as you said, during seasonal temperature changes, this chord will be much warmer than other parts of the truss. the span of the truss is about 32 feet, and the wall is approximately 4 feet from the center of the span, i.e. at the 12 foot point.

Reading about one of the solutions for truss uplift, the L-bracket that allows truss movement above the top plate of the wall, I wanted to see how my wall is attached to the truss. I found that the builder toe-nailed each truss to wall plate, usually just one nail was used. So, truss movement is under strain as seasonal temperatures change. NOTE: during our Idaho winters, we have no noise problem, or very little. Now that summer is close, the noise has returned, dramatically.

Here's my question: everything I've read, since you alerted me to truss uplift, indicates that the problem shows up as a crack between the sheetrock on the ceiling, where it joins the wall sheetrock. We have NO cracking like that. Our problem (forgive the layman discription) is a loud cracking SOUND that seems to be at the intersection of the wall and floor, and is transmitted thoughout the wall..my drumhead analogy. Is it possible that the way the non-load-bearing wall, the runs perpendicular to the trusses, was built, during the spring/summer time when the bottom chord would not be flexed upward, it puts presssure/strain on the wall, "jamming" it toward the floor, and we get the noise. Also please note that the noise is not constant. When we downstairs for several hours, it seems like the wall "loads" and when we then walk down the hallway, the load is released. The noise is very loud but once we've released it, as long as we continue to walk around, it is gone.

I'm hoping you, or others, can tell me if truss loading, or the way the builder toe-nailed the top wall plate to the truss, is still the source of my problem, even though I don't have the more common ceiling-to-wall sheetrock cracking. Thanks again for your help.

Re: Noisy 2nd floor

A clarification to my last posting...the home was built during the fall and winter.

Re: Noisy 2nd floor

Britan ... thanks for the feedback.

It could still be influence from truss movement.... considering the wall seems to be located approximately center of the truss span.

Even though there isn't one of the usual signs ( separation of the wall/ceiling drywall) there seems to be the other indication ... noise ( sharp crack or pop).

As you describe the wall structure is somewhat rigidily fastened to the truss lower cord without any type of slip connection.

As the truss moves downward it would exert a force on the wall and the floor structure creating a noise.

The same could happen as the truss moves upward ... pulling up on the wall structure and sliding on the fasteners in the bottom ( sole) wall plate.

As structure is stressed it will create noises ... whether it's the wood itself or the noise from the wood sliding on the fasteners.

Mostly the noises I've encountered have been when walls are located between floor joists ( running parallel) and merely resting on the sub floor ... though in your case the wall runs perpindicular to the floor joists .... I'm guessing.

It's possible when you are walking around upstairs you are loading the floor structure downward which might be allowing the wall structre to release some of the compression it's under.

When the opposite condition of the wall being pulled upward may be pulling on the floor until you walk on it creating the downward force .... relieving the tension being exerted.

The time frame of when the home was built may indeed have some impact .... as well as when the trusses were made , also the quality of lumber the truss maker uses.
Moisture content of the lumber at the time of construction would influence this.

Another area .... would be the integrity of the vapor barrier at that specific area.

If this vapor barrier is compromised then changes in humidity along that bottom cord of the truss would be occuring.

Of course this is sight unseen over the internet and is a best guess situation.

Side note ..... something that's worth mentioning.

You indicate your builder has been very helpful and cooperative in trying to resolve the issue 3 years later .... it sounds as though you are fortunate they care about their homes and if they are comitted to resolving the issue .... they deserve a giant pat on the back.... good for them.

Just some thoughts. :)

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