The most off-putting thing about a hot tub is its obnoxiously loud motor. Every hot tub owner needs to soundproof their tub at some point in time.
How to soundproof a hot tub motor? Perhaps the best way would be to isolate the tub from the surface down below as you cannot possibly insulate a motor (would overheat!). The ideal approach is to dampen vibrations from the motor with a sound-absorbing material put on the shell’s underside and frame corners.
Another way is to create a noise-free enclosure around the hot tub! It could be done by building a brick or wooden enclosure around it, covering it with mass-loaded vinyl or placing the tub in the ground.
How Loud Is A Hot Tub, Exactly?
Your hot tub could sound a little too noisy for a ton of reasons, but how loud can they get?
For instance here, suppose your hot tub is about 15 feet from your room, you will hear more of your hot tub’s noise than of your neighbor mowing his lawn. This is because hot tubs make somewhere between 40 DBs and 67 DBs of noise!
To give it some context, a normal conversation is around 60 decibels, a quiet library will register about 30 decibels, and a jet taking off is about 100 decibels!
Many factors influence the hot tub humming noise, like its current or usual settings, brand, and model of the hot tub. Even the ones marketed as “silent” make noise, though at a lower decibel.
Now a conversation sounds pretty bearable but the hot tub’s hum is quite annoying and relentless although they both are at 60 decibels. This is because conversation DBs have peaks and troughs, unlike the noise from a hot tub motor that is constant and unsparing.
Why Are Hot Tubs Noisy?
Hot tubs have motors that power the pump to circulate water, with jets and heaters. It does a lot of work and while doing so make a LOT of noise!
There are several different possibilities your hot tub could be making noise in addition to the killer motor sound. Some common reasons are:
A hot tub motor is placed inside a casting with circuitry running off to the parts it gives power to. The vibrations from the motor transmit to the mount and other surfaces that the motor is in contact with. This is a classic example of impact noise.
You’ll receive most of the complaints regarding your hot tub motor’s noise from your neighbors. They are the ones who hear the constant deep bass humming noise. This hum is hardly noticeable when standing near to the tub or inside it, but is clearly heard and felt from a distance.
This is due to vibrations and waves from the pump in the cabinet of the tub. Vibrations mean small movements, and with time, these movements loosen the bolts that hold the pumps tight. You may also hear squealing noises from the pump that indicate worn-out bearings.
The vibration, reverberation, and humming are multiplied if the hot tub is placed at the wrong spot or decking.
If the tub is on top of a deck, it is bound to make noise! This is because the decking is hollow and acts as a sounding box. And just like acoustic guitars or violin, sound waves can reflect freely inside the hollow box and sound much louder than they are.
The motor’s casing is usually made of either wood or plastic, both of which are exceptionally good transmitters of sound waves.
The problem is that you cannot put too much insulation inside or around the motor housing. If you do so, it can insulate heat as well. This means the motor can easily overheat and catch fire!
The sound of bubbling, squishing, and moving water in the hot tub are all the water sounds. This, again, is a continuous sound just like humming that the motor creates when the tub is on. Imagine both these sounds together!
Seized Hot Tub
There are a few signs that clearly tell you that your hot tub has seized. Like the buzzing and humming sounds more than usual, or water in it isn’t getting hot, or the control panel shows DR, OH, FLO, or DRY, or the jets don’t start.
This usually happens when bearings wear out or some debris is trapped in them. A motor with bad bearings will make a loud screeching or grinding noise.
Obstructions force the pump to work harder and make more noise while doing so. In addition to the premature wear and tear, a loud pump will eventually stop working!
How To Soundproof A Hot Tub Motor?
There are some things you need to do before you get to soundproof the tub.
First, clean the filter! The pump has to work harder (and make more noise) to push water through a dirty cartridge filter. Remove the cartridge dump and hose it. You may also replace it if it’s worn out.
Secondly, you need to check if the pump mounting is secure. Loose mounting can cause the whole filtration unit, filter, motor, pipes, etc., to vibrate. Check all the mounting bolts with a spanner or socket wrench.
Before soundproofing a hot tub motor, make sure that the sounds it’s making are normal. Noise from the pump can indicate a bigger problem if it’s higher or stickier than usual.
Be careful about extra humming, grinding, or buzzing sounds or if the water isn’t heating up or moving around in the tub as it should. Fixing these issues before insulating the hot tub will save you from future breakdowns and extra costs of servicing it back to life.
Soundproofing Solutions For a Hot Tub
Here are some proven soundproofing solutions for a noisy hot tub!
Sound Deadening Mat
Mostly, sound deadening mats are used in vehicles to mitigate noises from the road, engine, and surrounding environment. They are composed of butyl rubber, which is an excellent sound insulator.
You need to isolate the bottom of the motor where it connects with the surface below it to minimize the transmission waves and vibrations. Line the bottom with a sound deadening mat or sit it on the mat if the housing isn’t fixed to the floor.
You must also line the outside of the housing as well. The reflective backing of the mat reflects away sun rays and prevents the motor from getting too hot. You can easily do it yourself! Simply measure the base of the motor casing, mark and cut them on the sound insulating sheet, peel, and stick!
A sound-deadening mat will soak up movements and reduce noise as a result.
They are designed to be thermal insulators, so all you need to be careful about is not to line the insides of the casing. If you do, it’d trap too much heat and overheat!
The surface your hot tub sits on makes a huge difference in the amount of noise it makes.
A wooden deck sure looks exquisite but is probably the worst choice for hot tub noise! When you turn on a hot tub that’s placed on a deck, the loose slats will vibrate easily and almost vigorously with the motor. And as aforementioned, the empty space underneath will amplify the sound waves.
A concrete or brick base is perhaps the best surface to put a hot tub on. The more solid your base is, the less vibrations it can transmit.
Another effective solution is to put some anti-vibration mats on the surface the tub sits on. These mats promise at least 95% noise reduction with bolt-isolation rubber grommets. These grommets control noise from screws and bolts.
Setting the base strong will also address other concerns, like noise and reverb coming from the heater, pump, and jets!
Casing for Motor
As we have established, a hot tub motor is the main culprit for most of the hot tub noise.
Only the most expensive of hot tubs come with insulated motors. However, you can easily cut down the noise decibels to quite an acceptable level by insulating the area around your hot tub’s motor.
You have multiple options for materials and ways you can soundproof a hot tub motor. Some commonly used are:
- Fiberglass insulation; When dealing with fiberglass, make sure you wear gloves, a mask and full sleeves as it can easily irritate the skin.
- Foam Insulation; Foam could either be from a spray can or solid pieces cut and attached to the walls of the casing.
- Cover that embraces the motor from all sides.
- Sound Deadening Material; preferably mass loaded vinyl (MLV)
- Acoustic Caulks and Foam.
If your hot tub motor is fitted inside the main body, it might be impossible to create an enclosure around it . The best you can do is put a soundproofing sheet under the motor. While in other cases, the hot tub motor is screwed into the base.
To soundproof a hot tub motor, line an adhesive soundproof sheet beneath the motor case or housing. It’s an easy process where you start by measuring the base after you open the casing from the base.
After marking the measurements of the base of the motor’s case on the backside of the sheet, cut and peel it. Apply the sticky part to the walls of the case and smooth it out with a smoothing tool. Let it dry and fasten the screws back to it.
A better approach here is to make an enclosure box for the motor. Where you measure the motor and add a few more inches to it to incorporate ventilation space. It is usually done with a medium-density fiberboard. MDF is cut to fit each side and the lid as well.
You’d need to cut two holes for ventilation, one at the back and one for the lid. Adding more holes will of course enhance ventilation but will reduce soundproofing ability. You can also glue a layer of acoustic foam on it and seal edges with acoustic caulk. Sit the box on the motor and you’re done!
Hot Tub Enclosure
If your hot tub is just sitting on a bare surface without any enclosure around it, there’s nothing that can stop noise from escaping it!
A hot tub enclosure is created from a soundproofing material to effectively reduce the transmission of sound from the sides and below. The biggest advantage of doing so is that you won’t need to focus too much on the motor separately and risk “too much insulation” there.
If it is possible, consider sinking the hot tub into the ground. This means you’ll be enclosing the tub into the earth, which is an excellent barrier to sound transmission. This can drastically absorb grinding, buzzing, and screeching sounds from the tub.
Alternatively, you can build a case or enclosure around the tub with paving slabs, bricks, or concrete and keep it above the ground. If you wish to build a case out of wood (though it isn’t recommended), line it with mass-loaded vinyl or any other dense material to increase the mass.
Surrounding the tub inside a full barrier will not only control sounds but will also effectively maintain the temperature of the hot tub. It can prevent a significant amount of heat from escaping the tub.
Placement Of The Tub
You, and everybody around you, can enjoy more of a hot tub if it is placed at a great location. That means placing the hot tub as far from the property line as possible. You can also place the hot tub in a way that the motor, which is the loudest part, is not facing any of your neighbors!
Moreover, you should avoid putting the tub far away from your own building into the open air. Keep it as close to trees or parts of your building to avoid exposure to wind. Wind can blow a significant amount of noise from your tub to the people living nearby.
Fill Gaps With Spray Foam
Spray foam or spray polyurethane foam is a widely used plastic insulation material and is applied with a spray. It has proven to seal cracks or gaps to insulate buildings and make them more energy-efficient.
You can seal the deep crevices that surround every component of a hot tub. There’s only one thing you need to be very careful about when spraying. That is to make sure you don’t close the air vents when spraying the internal components.
Spray foam is not only fun but is the easiest way of insulating the small parts that might collide to create noise or create hollow spaces to amplify it. Make sure that the inner side of the hot tub box is free from any debris and rust.
Connect the dispenser with an insulation can and spray uniformly. Avoid any metal or copper ventilation pipes or components you see. Let the foam inflate and put the panels back to close the casing.
Every hot tub is going to make some decent amount of sound when it operates. As long as you keep realistic soundproofing goals regarding your hot tub, these tips will help you.
If by “how can you soundproof a hot tub motor” you mean a way to get a 100% noise-free hot tub, you will be disappointed. Especially if it’s more than one person using the tub, as the sounds of water gushing and moving will make people interact in a louder voice.
To summarize it all, hot tub noise is mostly from the motor or could be from a hollow or weak base creating more vibrations than it should. Ensuring all nuts and bolts are tight and using soundproofing material under the tub, on the motor case, and around the enclosure will help!