Noise Disturbance - Exhaust Fans not built to code

[WesternHemisphere]

Hello,

Have an interesting dilemma with a neighbor. We moved in a year ago into a neighborhood on a hillside. Months ago we noticed a pulsing noise resinating through our house from the neighboring property (the increase in sound I believe is due to a failing exhaust fan increasing the noise from before).

In short, they have a large house with a massive crawl space, 16' ceiling which they have the entire area being vented directly at our house. The issue is four 17" attic fans individually being vented through two 8" pipes each. Each set of two fans are in two separate areas. The fans are oversized and vented unproperly creating a pulsing noise within their crawl space. The two fans in tandem are bouncing air off their cinder block wall creating this low pulsing/rumbling sound. The noise is heard in my kids room, my office, the other side of the house in our bedroom and it's heard throughout our property outside. Basically everywhere.

I offered to help and initially was welcome into their home. We also had an HVAC tech go to their house and recommend smaller fans to be inline with the 8" pipes. I offered to pay half. I even bought fans we agreed to install together. They were struggling with bigger fans means more air getting moved. Well, that was about 4-5 months ago and during that time things have gone south.

I filed a complaint with the City. The City is stating that the noise is not over the disturbance level by decibels. Moreover, they are assuming the fans were permitted during construction in 2005 and stated that they are unsure if the fans even require a building permit. Currently, I have an email back to the City stating that a building permit cannot be based on "assumption" and these fans are not built to code. Requesting a reply back before we escalate this with the City further.

We don't have much neighbor support because everything is vented toward our house.

Well, we will do everything possible to fix this. The neighbors are now unpleasant and won't return our correspondence. The City said to file a police report. Personally, I believe the City Building Department is responsible. Also, I'd prefer not to hire an attorney; perhaps this is the route we need to go.

Any advice is welcome on the best path forward to resolution.

 

[ICE]

I believe is due to a failing exhaust fan

Does the noise stop when the fans stop? Have they tried dropping out the fans one at a time to see if the noise stops? Do the neighbors notice the noise?

We also had an HVAC tech go to their house and recommend smaller fans to be inline with the 8" pipes.

Did the HVAC tech offer an opinion on the cause of the noise?

these fans are not built to code

What do you base that statement on?

The City said to file a police report.

Bad Idea. The police won’t know what to do for you.

I believe the City Building Department is responsible.

I believe that the city has no responsibility for this.

Did this problem happen suddenly? Has anyone checked the fans to see if one is out of balance?

 

[WesternHemisphere]

Does the noise stop when the fans stop? Have they tried dropping out the fans one at a time to see if the noise stops? Do the neighbors notice the noise?

Yes. When things were going okay. We figured out that one fan was the major culprit...turning it off reduced the issue by more than 50%. They said that it was getting "musty" in their basement unit over the crawl space so they turned both back on. Which is really the big problem...two fans in tandem bouncing air off the wall because all the air does not escape to the outside. Only one other neighbor notices but he is lower and the impact is not the same to our household/property.

Did the HVAC tech offer an opinion on the cause of the noise?

Yes. The oversized fans. The opinion/quote was to change the fans out with a size in line with the 8" pipe. Which would eliminate the pulsing sound issue.

What do you base that statement on?

Looking at manufacturer installation guides. Some state to build a box around the fan when there is obstruction to the fan diameter. The issue is air bouncing off the cinder block wall and the two fans bouncing the noise off each other. I'm a planner and not a building code expert. I need to contact my building official friend to see if there is international building code guidance. To me it does not make sense to install an exhaust fan that has obstructions in front of it...and it causing a noise disturbance. My it's a guess at this point other than the installation guides.

Bad Idea. The police won’t know what to do for you.

This was the suggestion by the City code enforcement official after he took his decibel reading. He said the noise disturbances to property need to go through the police department. I agree with you which is why I've held off. It will increase tension for certain. It's probably better to hire an attorney which is what we are trying to avoid.

I believe that the city has no responsibility for this.

Did this problem happen suddenly? Has anyone checked the fans to see if one is out of balance?

I've always noticed the exhaust fan noise. But it has got worse over time and perhaps they did not have all the fans on as they work on a humidistat.

Truly appreciate your input.

* Today unfortunately they fixed one of their broken fans. Now the sound is even worse. This is such an odd set-up...and unfortunately these neighbors don't care as they don't hear anything....everything vents to our property. When you walk past their property line and the noise is not there.

 

[ICE]

Did the HVAC tech offer an opinion on the cause of the noise?

Yes. The oversized fans. The opinion/quote was to change the fans out with a size in line with the 8" pipe. Which would eliminate the pulsing sound issue.

Does the noise stop when the fans stop? Have they tried dropping out the fans one at a time to see if the noise stops? Do the neighbors notice the noise?

Yes. When things were going okay. We figured out that one fan was the major culprit...turning it off reduced the issue by more than 50%. They said that it was getting "musty" in their basement unit over the crawl space so they turned both back on. Which is really the big problem...two fans in tandem bouncing air off the wall because all the air does not escape to the outside. Only one other neighbor notices but he is lower and the impact is not the same to our household/property.

Fans are not all created equal. Some are noisier than others. Removing one fan reduced the noise by 50%...an estimate.
It certainly seems odd that the occupants of the humming house are either not aware of, or are resigned to the noise.
The configuration that you describe ... 17" diameter fans with two 8" round vents is not complete without pictures and or a drawing with dimensions.

Worth noting is that attic fans are always located at an exterior wall with a full sized vent. You make it sound as though the fans are some ways into the crawlspace with pipes for venting. Just a thought but that would be next to worthless.

The ventilation layout is germane in that the four 17" fans are trying to expel a lot a of air. There's a need for makeup air.

They said that it was getting "musty" in their basement unit over the crawl space so they turned both back on.

Code compliant ventilation should be sufficient to avoid a moisture problem. If there is an issue with moisture, an increase in the ventilation would be a start. In addition to everything else is the idea that one properly installed fan should be all that's needed. It not like they are flying a kite. They're just trying to slowly replace the air.

It’s the weekend and come Monday plenty of smart people will see your OP and hopefully someone with the answer will chime in.

 

[e hilton]

Several loudspeakers pointed at their house playing Lawrence Welk music. Anna one anna two.

 

[ICE]

It’s the weekend and come Monday plenty of smart people will see your OP and hopefully someone with the answer will chime in.

Looking for answers. Hopefully there is settled science on the phenomena exemplified by the OP’s dilemma.

 

[BN4537]

I would use a properly sized dehumidifier in the crawlspace area, and close off the openings to the exterior. Eliminate the fans altogether. See R408.3,2 in the 2021 IRC.

 

[klarenbeek]

Sounds like extremely large fans to ventilate a crawlspace, even a large one. With the amount of air those are probably capable of moving, if there's not provisions for fresh makeup air to enter the crawlspace that could also be a cause of the noise. The fans are starved for air to move so they will make more noise. My air mattress for camping has a built in fan for inflating and deflating. When the air is all sucked out the fans noise is a higher and much louder pitch, and this is a tiny little 3" plastic fan. It would also explain why they still have musty problems even with oversized fans.

Unfortunately, barring a noise ordinance violation there's probably not much you can do to force them to fix anything. Unless there's an active permit the building department may not be able to do much without hard proof there are code violations.

Without any other options I would build a privacy wall on my property to bounce the sound back at them.

 

[bill1952]

OK, I'm confused. Are the fans directly exhausting the crawl space or the attic?

Definitely sounds like lack of make up air whichever and some cavitation.