Thread: How to Install Carpet over Dynamat.

Originally Posted by Reads90

How do you come up with that. I can't see how it make a noticeable difference to noise if it is glued or lose lay the carpet

Noise is transmitted vibration. If you bond everything together, it transmits vibration (noise) quite well. Which defeats the purpose of the exercise.
If layed over and fastened at edges or at intervals it is far better at not transmitting noise.

Originally Posted by Reads90

And if you want to use closed cell foam then why bother with the dynamat.

Closed cell foam and dynamatt work in completely different ways. They are not interchangable for noise reduction.
Dynamat by itself is very poor at stopping noise. But combining a deadener (dynamat, roof-flashing tape etc) and an insulation layer (closed cell foam) with a top cover (carpet or rubber) you get a very good result.
The heavier the top cover, the better.
The layers also need to be able to move slightly to dampen vibration and the more layers the better. Two layers of 3mm foam are better than 1 layer of 6mm foam etc.

You are worried about overkill, but your original idea of gluing carpet to dynamatt is just wounding the noise and letting it die a miserable death somewhere inside.

For the next tip, deadeners (dynamat, roof-flashing tape etc) does not need to be full cover. You only attach enough to deaden the panel and stop it ringing.

If you are worried about the carpet bunching, I would glue it to something more solid (sheet of hard-board, HDPE plastic etc) that lays on top of the central floor. For the sides it'll support well being fastened at the edges.

I run similar marine carpet in the back of my work car. But it's not bonded to the floor.
The floor is steel deck, which has the factory tar deadener stuck on.
On top of that is 10mm closed cell foam.
On top of that is the factory vinyl flooring.
On top of that is the wooden organiser rack bolted down gently at the corners and covered in grey marine carpet.

This works very well, the factory deadener stops the floor ringing, the 10mm foam stops the higher frequencies and the rack on top stops the lot from drumming by providing more stiffness to the floor than dynamat/flashing tape can.

Thank you to everybody who contributed to this thread.
Since asking the question and due to the discussion on this thread I have undertaken further research.
Dougal you are correct in what you say for optimum noise reduction and Reads90 you are correct as far as "look " is concerned.
AS always a bit of a trade off.
Cheers
Tony