Maximum permissible thickness of sound-proofing material in ceiling

[avm]

Hi,

Can someone please advise the maximum permissible thickness of insulating material (e.g. sound dampening material) that can be located between the roof and the ceiling liner?

For maximum sound control, I am seeking to adhere to the underside of the roof a material having the following characteristics:

* Rigidity - Increasing the stiffness of the of roof's sheet metal to make it less prone to resonating and vibrating
* Mass - Adding mass to the roof to make it more resistant to vibrations from both outside (e.g. wind noise, vibrations transmitted through the body from drive train and suspension) and inside the cabin (i.e. any noises that are bouncing within the cabin)
* Absorption - The thicker the material, the deeper the pitch of frequencies that can be absorbed within the cabin

I am considering a range of ways to achieve these effects, ranging from installing a sandwich of different materials to creating one of those meta-materials that I have been reading about lately. Regardless, all this theory is useless without knowing how thick the material can be.

For the benefit of others on this forum, I am considering making before-and-after sound level measurements so as to be able to share them with forum members, especially if the approach that I take happens to be unique.

[Errol62]

Just remember to consider the weight factor, as well as insulation. I read recently on the EH EJ firum where someone had to remove a lot of expensive sound deadened to reduce the vehicle weight for engineering. I also read that optimum sound deadening panel cover is 60%.


FB ute fixer upper, EK van on rotisserie

[Blacky]

The hood bows sit hard up against the factory applied sound deadener which is only a few mm thick , I would imagine anything more than 5mm would affect the way the headliner sits - perhaps not an issue if you are retrimming the car but if you opt for something thicker than 5mm or so you may need to consider shortening the hood bows to compensate for the thickness of the insulating material

[62ekute]

I used this lightweight one in the EK .. no problems ... (see 'gimme 5 years' thread)

https://www.ebay.com.au/itm/Car-Builder ... 2749.l2649


and this one in the campervan to stop the long panels vibrating

https://www.jaycar.com.au/combination-b ... gJhTPD_BwE


P.S. don't go with the cheapest ... I've had trouble with one 'dripping' on another car (and even just sitting in the shed) ... okay on the floor but you don't want that up top or down the sides

deadener 2.jpg (58.77 KiB) Viewed 394 times

[avm]

Thank you.

[FbSTDwagon]

I lined my roof with UnderDog deadner off eBay.
Worked really well and I’d definitely use it again
I’d say it about 3-4 mm thick when rolled on.

I did Howe remove all of the factory roof lining which was a PITA as mine was on the rotisserie and I was pressure cleaning the body and it started to bubble.
I’d say if your roof insulation is stuck fast you can leave it and it’s absolutely fine, but if you put another layer on top it will e too thick like blacky mentioned.

My hood bows were tight AF to get in with the single layer of UnderDog.