Intermittent Popping sounds in Roof Structure 2

[msquared48]

I have a project where the client is hearing periodic popping sounds in his plant manyfactured roof structure after 30 years, He has the original owner and has structural drawings that I am studying. Two locations are involved, one at a major girder truss location, and the other near a hip master. Of what I could observe in the attic space, the truss structure looked good. There is no outside evidence of any sliding or rotational settlement, no Sheetrock cracking and do impaired doors.

I am mystified, with no overload conditions in the recent past, why two different locations would be acting up after 30 years of silence.

Anyone ever run into a similar situation? The client is really disconcerted and looking for answers.

Mike McCann, PE, SE (WA)

 

[WesternJeb]

Skyscrapers have had this happen when there are short-slotted connections that are snug tight end eventually "slip" into place, then make a very loud "pop" as they bolt hits the end of the slotted hole in the shear tab. This has been noted to happen anywhere from one year to multiple years down the road. This could be developed from a loss of friction between the bolt/nut/plate over time due to various reasons, which could explain what causes it to happen so far down the road versus specifically with high loading or high temperature stresses.

I am not sure the applicability to your situation, that is just one of the instances I have heard of this "popping" in structures.

 

[Eng16080]

Have there been recent abnormalities in the weather (very hot or cold or extreme humidity) or similar changes in the internal environment?

 

[phamENG]

I have a 35 year old site built home, all stick framed. Late fall and mid spring, when we get daytime temps in the 70s and 80s and night time temps down into the 40s or occasionally 30s, it sounds like a kid playing with pop rocks in my attic. Okay, that's an exaggeration, but there's plenty of shifting and popping.

After 30 years of cycling stresses, maybe something just isn't quite as snug as it once was and is starting to make some noise.

 

[bones206]

If the noises are happening around the same time on a cyclical daily basis, that would suggest thermal movement.

 

[3DDave]

Try a look with a thermal camera to see if anything is a notably different temperature - only a few degrees is required.

 

[StrucPatholgst]

This is the time of year that the heat is cranked and the framing is drying out and contracting. Could be that the attic framing is adjusting to the contraction in the of the wood in the lower floors, which may have gotten wet from a recent leak (roof, plumbing, etc.).

 

[LittleInch]

Mike,

Wood? steel?

Type of connections?

Any drawings?, pictures?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rb1957]

could be a bunch of teenagers in the attic, cracking tinnies ...

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[msquared48]

The space for the trusses is unheated, so temperature fluctuation is very suspect, but taking 30 years to present is odd to me.

I have no idea on the type of truss end connectors that may have been used, if any, yet.

No roof leaks either, old or new. The house is very well maintained.

The only concern I saw stemmed from the original construction involving the connection of the main floor joists to the back concrete basement wall. All I saw was toenailing which would be inadequate for retaining 8 feet of soil. The house is cut into a bank with a water view, and I suspect some of the foundation is on fill on the downhill side. Settling is not an issue as there is no indication of that in the foundation itself. Moreover, as previously mentioned, there is no interior Sheetrock cracking anywhere, and no door issues.

The more I consider this, the more I think this is temperature related with the truss attachment to the frame finally allowing movement after 30 years. To me, that is the most likely and reasonable answer.

Mike McCann, PE, SE (WA)

 

[dvd]

Has this house been re-roofed? Any other maintenance or repair activities?

Suspecting wind pressure variations may be involved.

 

[msquared48]

DVD:

No roofing or repair issues.

As for the wind, it is exposed to a southeast open water situation with probably a high Kzt factor, but the noise is not associated timewise with any wind gusts.

Mike McCann, PE, SE (WA)

 

[msquared48]

Thanks for the comments…

Mike McCann, PE, SE (WA)