Hi, i was speaking to a guy today who recommended using polyurethane spray on liner in my van to act as a sound deadner. Obviously being a commercial vehical there is alot of bare panels just waiting to be energised. I was advised that the spray is applied 4mm thick and by adding mass will limit issues with panels resonating. He also mentioned that there would be a considerable improvement from road and engine noise also? I was quoted approx $1200-1600 to do the full interior i.e. walls, floor, roof and tailgate. I was also quoted another $240 to apply 20mm thick rubber to the floor, then coated with the polyurethane spray? I was wanting to know if anyone had any experience with polyurethane as use as a deadner?I was told the spray on liner works better then the Dynamat original, and fuses/seals all the panels to the structure of the vehicle adding increased regidity. I am very queries on peoples thoughts, especially those with knowledge on the subject.

I have read the countles threads, obviously still trying to understand the principles of deadening and blocking and which medium would be best suited to each application. I am hoping to achieve a decrease in road noise combined with limiting the resonating frequencies within the vehicle, with a few to seriously enjoying my tunes whilst embarking on weekends away with the misses.

I am obviously a little dubious about spending that much money on a product which may not be suitable for what i am trying to achieve. Any feedback would be much appreciated, or other options? I have included a few links for peoples interest.


Links:

http://www.infolink.com.au/c/Polyguard/Sou...lyguard-n769387

http://www.polyguard.com.au/

for that much you could buy a lot of dynamat extreme

id doubt it would be better

I have had a little of experience with the poly lining of tanks/cells, but have never thought about using it for Deadening purposes.

It could potentially work. It is a spray on process that requires a special primer before application, this could get messy inside a vehicle.

We used a 4mm thick layer of poly insde the tanks we had made and had them spark tested after aplication to ensure a good application.

For that much you could get up to 6-7 bulk packs of dynamat, you could just about double layer the whole car with it. Dynamat is tried and tested and well known to work wonders on a audio setup. Id just go dynamat mate

The clue here is "adding mass" to the panels, I don't doubt the polyurethane would work as good if not better than Dynamat, purely because it's adding mass with superior adhesion and rigidity. It will also double as a good protective surface. The Polyurethane gets my vote as Dynamat can only serve ONE purpose in this application.

Yeh, but thats too much money to pay to add mass IMO.

urgh.

If that was the sole purpose of the application maybe I'd have to agree with you BUT Dynamat is not an impact resistant medium for the load space of a commercial van. There could be more than one reason for the application of polyurethane where Dynamat has limitations. I'd take a guess and say the coverage would be comparable. Would the same amount of money spent on Dynamat cover the same amount of area at the same density? It would be close.

P.S. Is there a substantial difference in weight between the Polyurethane & Dynamat, that would be something to consider given it's a commercial vehicle, doing many Km's per day.

Mate of mines done his ENTIRE patrol in this stuff and its cut back road noise substancially. its still not as quiet as mine with dynamat (and mines not quiet) but for a DX with vinyl floors and NO underlay at all its fairly quiet.
The added bonus is he can chuck crap in his car and hose it out afterwards

Im with the others that say thats too much money for what your getting.

However, can I offer a different way of looking at it. How about Isolating the cabin from the rear. A well sealed cabin will minimise the amount of noise transfering from the back to the front. It will also let your A/C work better etc. Then you can concentrate on deaning and sound insulating smaller areas like doors, roof over the cabin, wheel guards on the inside, etc. This will cost less due to less materials being needed too.
I think this would go along way to achieving what you need with out the expence on the back of the van which is really not needed.
For sealing the cabin, i suggest a perspex sheet with a foam seal, siliconed in place. Or even painted/treated MDF one. Basically anything that will split the rear of van from the front. The better you do this the better it will work. Sound is carried by air. So if you can reduce the amount of air coming from the back into the front you have halved your battle.
The other area that is noisy in vans is the engine compartment, which is ussually accesed under the front seats. So look closely at how you can improve that. Rubber backed Carpets (ie like an old set of cheap floor mats) and deadning products (like Dynamat) combined, can work really well.
I hope that helps, as I know how fustratingly noise Vans can be on the open hi-way. Good luck.

Maybe so if looking at it from only an audio instal point of view, but from the "commercial" angle it may be the going rate to provide a hard wearing surface to the storage area.....in that respect the sound deadening is then a bonus by-product. I think Syds recommendation is certainly more economical as well as being possibly the best option.........seal the cabin from the storage area.

Thanks all for the feedback, I have been umming and arring for quite some time whilst gathering all the gear for the install. I really like the idea of isolating the cabin form the rear of the vehicle, but thought i would still be required to apply deadening to the rear to avoid nasty rattles/ resonating panels due to the sub? Unfortunately the battery and reseviour are situated behind the drivers seat and acess to the motor is via lifting the passenger seat, which limits placement of the sub. I suppose the work around would be to try and incorporate the sub into the dividing wall along with the amps? Maybe the wall would enable the sub to be run free air? or a seperate sub enclosure woud have to be designed which could be incorporated into the wall?
Would having the amps close to the motor increase the chances of unwanted electrical/ engine noise being added into the audio path?

I had come to the conclusion that even after having the polyurethane applied i would still need to apply some form of decoupler which again would bump up the cost associated with the poly liner. This would also add price if applying dynamat.

Adding a divider definitely seems more cost effective and would most likely produce the best results, but somethings i would need to take into consideration if building a divider would be the need to alter the roof lining e.g cut a section out to ensure a good seal. I suppose i don't have a problem with this? The other issue is the lack of ventillation to the rear of the vehicle for the dog, especially in summer? Would having a perspects window defeat the purpose?

Second thoughts, some of the added expense re the Polyurethane came from the need to prep the vehicle e.g pull out roof linings, mask up the interior etc. It maybe possible to reduce those expenses by building a wall, taking out the roof lining to the rear of the vehicle and only having the rear of the vehicle sprayed up to the wall which would give an air tight seal as suggested?

I cart quite alot of gear, Drum kits, Band gear, motor bikes (not so much anymore) mountain bikes and general stuff in the rear of the van and love the idea of being able to take a hose to the vehicle to clean it. I will get nother quote to see how much this would set me back. Can anyone see any potential issues sound wise re having a more confined space for audio upfront?

No issues, only bonuses. How much space rearward are you prepared to lose?. Build the dividing wall thick enough to house your sub (forward firing) and amps. Include a window for rearward viewing but for ventilation get a roof vent (whirlybird).

Would i need to look at deadening the rear of the vehicle to avoid resonating panels? or would deadening the roof above the cabin and sealing the wall air tight surfice? I am prepared to deaden the rear, but if i dont need to that money could be better spent elsewhere. Thanks again for the input.

Unfortunately I can only assume that sealing the cabin from the rear will isolate most of the resonating panels to the the rear only. As most of it will be road noise I don't believe it will become audible in the cabin, unsecured payload rolling around in the back may be another matter................

poor dog... has to put up with 30-80Hz of sub frequencies... lol