Featured Question for those that have sound deadened car doors to improve mid range woofer sound:

NorthFramingham said:

I have a 2024 Subaru BRZ. I already sound deadened my trunk area and rear seat area. I am adding the sound deadening to improve the sound of my door (2ohm 6.75") mid range woofers; not necessarily doing it to reduce road noise or outside noise. I am keeping my factory head unit and speakers for now.

The products that I have on hand "so far" are Canopus 80mil (about 24-26 square feet) sound deadener, 1/4 inch closed cell foam, 1/8 inch closed cell foam, Butyl Tape and rollers.

My Question is:

What did you choose to cover the large access holes in the doors and why???

1). Crutchfield recommended just going over it with the butyl backed sound deadening. (A.I. recommended against this)

2). I have read some D.I.Y.'s used Closed Cell Foam by itself. (A.I. recommended against this too)

3). Some pro installers use 1/4 hard plastic, cut to size and either attached with self tapping
screws; it would have a bead of butyl rubber tape underneath the edges to seal it.

4). Some pro installers recommend Aluminum sheet Metal installed in the same manner as the hard plastic
that I just listed.

5). Two D.I.Y.'s that I talked to; went with making a new vapor barrier out of 6mil polyethylene sheeting
(basically the same material used by the factory for a new vapor barrier).

Most people say that when you remove the factory vapor barrier it really should not be re-used; because it won't be as effective. Additionally I have read that the factory vapor barrier is usually damaged when its removed.

Admittedly I am a novice... and just want to make the best choice.

I don't want to do anything that will harm the car in the long run.

This is a picture of a car door that is the same as mine.

Click to expand...

It sounds like you're making great progress on your sound system upgrade! Regarding the access holes in your doors, each option you mentioned has its pros and cons. Here’s a summary to help you decide:

1. Butyl Backed Sound Deadening: While this method can reduce vibrations, it may not seal the access hole as effectively as some other options since it doesn’t provide a solid barrier.

2. Closed Cell Foam: This option is generally used for acoustic treatment rather than as a main barrier. It may not provide enough protection against moisture and outside noise if used alone.

3. Hard Plastic (1/4"): This option provides a good rigid barrier against unwanted sound while allowing you to secure it tightly, which helps with sealing. The butyl tape underneath can enhance the seal.

4. Aluminum Sheet Metal: Similar benefits to hard plastic but may be heavier. It provides a solid barrier and can be effectively sealed.

5. 6mil Polyethylene Sheeting: Replacing the vapor barrier with this material can help maintain moisture protection while being a lightweight solution. Just ensure it's properly secured to avoid rattling.

### Recommendation:
The combination of hard plastic or aluminum sheet metal with butyl tape is likely the best choice. It provides a solid barrier against sound and moisture while ensuring a tight seal. If you're concerned about moisture damage, you might consider adding a polyethylene sheet as an additional vapor barrier before applying the hard plastic or aluminum.

### Final Thoughts:
As a novice, it's great that you're considering the long-term implications. Be sure to carefully measure and cut your materials to ensure a snug fit, and take your time during installation for the best results.