Building Homes or Extensions/Loud booming noise in office building
QUESTION: Hello Bruce,
For the past 6 months in the office building that I work at on the second floor corner. There is a loud bang which sounds like someone drop 50,000 tons of weight on the building. When you are inside the tenants space where you can hear the loud sound you will also feel as if someone used a hammer and banged it underneath your feet. I have had 2 strucutural engineers, plumbing company, hvac companies come out to check the building and they cannot figure out were this noise is coming from or why it is happening. The building engineer onsite drain the entire water system with the plumbers on a weekend and the noise came back on Monday. I have been documenting the noises and you do not know when or what time it is going to happen but it just happens when you least expect it. I noticed this week that we had the sound for 2 days while it was a sunny weather. Last week we did not have any sun and there was no loud banging noise at all which is surprising until yesterday and today. This has to be a structural issue but the structural engineer cannot figure out what is causing the noise and both companies were surprised when they heard the noise that they have never heard of it before.
ANSWER: Hi Lori, very interesting! Before I can really venture a guess I would like a little more information. Is the building a two story building or are there other floors above you? Did this noise come on suddenly out of the blue? Has the air conditioning and or the ductwork been looked at? Over the years I have found that most loud annoying noises in large commercial type buildings are related to ductwork. Why? Because most duct work is sheet metal and sheet metal can expand and contract..large ducts expanding can pop or thunder under the right circumstances. If there is a roof top a/c unit nearby, and if that unit is ducted into a sheet metal plenum before it goes into the building it is possible that somehow the plenum got a big dent in it..that dent can pop in and out and make noise. I'm just speculating here so bear with me. Is there an open door, window, or other opening that could be slamming around with a gust of wind? It might be left open, slam shut when a gust hits it. When the noise is investigated. The door or window is shut so it is not suspected. But if you could give me some more info about the layout of the building and how big it is, whether or not it has an elevator, a roof top access door, anything that might help. Please write again..sincerely Bruce Johnson. Bejohnsonconsulting.com
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QUESTION: Yes the noise suddenly came out the blue and this building was built in 1982. The building is a 2 story and the noise is above me so when it happens it sounds as if the ceiling is going to collapse and when you are on the second floor you feel the flooring is going to collapse because it shakes and or vibrates. The roof top a/c is not located on that side of the building and the elevators are located on the opposite of the building as well. The windows cannot be open from inside/outside the tenant space and the entrance doors are not located near the noise. The hvac company stated the blower runs all day and it does not start or stop but it does stop after 6pm. We hear the noise during the day while the air condition is running.
Hi again Lori, I am intrigued by this. It's quite possible that something structural is going on here. If the building is constructed with steel bar joists maybe a weld has popped loose and when the weather is warmer or the roof heats up under direct sun, the joist expands and moves around on its seat. It's also possible that if there are steel columns with beams bolted to them or sitting on them, something has come loose. Steel decking over bar joists is welded to the joists. Too much movement in the bar joist may cause the deck welds to break causing a sudden release of tension. You say two structural engineers have looked at the problem though..one would think that they would have examined the connections. It would take a thorough step by step forensic investigation to isolate these types of issues, however, this noise and rumblings could very well be signs of imminent structural failure..I would recommend a ground up evaluation..
Start at the foundation and look for signs of settling, shifting footings, cracked slabs, doors or window openings out of square, that sort of thing. Then I would move to the floor system. I assume you have suspended ceilings..tiles can be removed and each joist (starting in the area where the noise seems to be emanating from. Check for separations between decking and joists. Check all joist ends and bearing points with a flashlight and look for cracked or broken welds, rust, water, rotten wood, loose bolts, missing bolts, broken bar joist webs or struts..I mentioned water because a leak over time can cause rust or wood rot and eventually bring on structural failure of some sort. So there may be signs of moisture penetration on or near the problem.
The same for roof joist inspections, look for all of the above in the roof structure.
I would eventually look at the walls outside if all else came up negative and look for siding or masonry issues.
It may sound stupid, but have you considered that you are experiencing sonic booms from jet planes passing nearby? Is there a military base or airport in the vicinity?
Just a thought..anyways..if you have any more information as to the actual structural makeup of the building I can possibly come up with other scenarios. Sincerely Bruce Johnson...bejohnsonconsulting.com