Noise Sources: 
Wheel / Tire
Air Turbulence / Wind
Panel Resonance

A door is complicated enough that we have to break it down into components for discussion. As with most things related to vehicles, inner, outer, front, rear, left and right are relative to a seated driver.

Outer Door Skin

Honda Civic Front Door Outer Skin

The outer door skin is the painted exterior of the door. It's often one of the vehicle's most resonant panels because of its size. It is a primary entry point for traffic noise. It can also carry engine and front wheel noise entering from its front edge and rear wheel noise entering from the rear edge. 

Inner Door Skin

Ford Mustang Cobra SVT - Inner Door Skin

This is the surface to which the trim panel is attached. It is the ideal place in the door for barrier layers (CCF/MLV).

Trim Panel

Saturn Sky Trim Panel

You will know more about your trim panels when this project is done than you ever imagined was to be known.


  1. Control resonance in sheet metal and plastic panels. Resonance creates its own noise and facilitates the transmission of sound through vehicle panels.
  2. Block sound inside the door from entering the passenger compartment.
  3. Improve tactile experience. Happy side effect of numbers 1 and 2. Doors feel more solid and open and close with a much nicer sound.

The Most Important Piece

Tesla S Inner Door Skin MLV/CCF Barrier in Place

This is what we want. A barrier on the inner door skin, trimmed to allow the door to function and the trim panel to be replaced without having to throw your shoulder into it. I've used this treatment, or variations of it, on dozens of vehicles. Customers have used it for hundreds more.

It might be easier to list the vehicles I know won't work: Some 2005-2010 Volkswagens and modern Minis. Late model Mazdas make it difficult but it can be done. Restoration from the '60s and before will probably have flat backed trim panels with no space behind them. Some vehicles have no trim panels at all. Most luxury cars will not respond well to this treatment. They will have already used the space we are counting on. Think of this as retrofitting luxury car characteristics to the doors.

It's not the end of the world if you can't hang the barrier on the inner door skin. Next best option is the outer door skin. Outer skin placement won't get the noise coming in through the doors edges but will still help with traffic noise.

Remove the Trim Panel

Dodge Ram Inner Door Skin Vapor Barrier
Mazda Protege 5 Inner Door Skin Vapor Barrier

The first thing you should see is the factory vapor barrier, usually plastic sheeting, attached to the door with some very gooey butyl adhesive. You will need to remove the vapor barrier to get to the outer door skin.  It's a good idea to clean up the messy adhesive before moving on. Tear off a small piece of Extruded Butyl Rope and use it to dab at the factory adhesive. Most of it should come off. Mineral spirits will remove any remaining residue. If possible, you will want to replace the factory vapor barrier when you're done with the door. A thin bead of Extruded Butyl Rope will work perfectly in place of the original adhesive. Both CCF and MLV are impervious to moisture and can function as a vapor barrier if you can't replace the factory vapor barrier.

Some Doors Have Styrofoam Blocks on the Ouyter Door Skin

Mazda Protege 5 Door
Saturn Sky Door

These blocks are there to stabilize the window glass. You want to keep them. They are usually attached with clips. It can be easier to work on the outer skin if you remove them before you install the CLD Tiles™. Worth considering putting a CLD Tile™ behind them. Don't forget to reinstall teh blocks before you move on to the inner door skin. Not a good feeling to get the trim panel back on and seeing this things lying in a corner.

Press Extruded Butyl Rope into the Gap between the Side Impact Beam and Outer Door Skin if it is not Already Filled

Mazda Protege 5 Side Impact Beam
Mazda Protege 5 Side Impact Beam with Extruded Butyl Rope
Ford Mustang Cobra SVT Side Impact Beam Extruded Butyl Rope and Aluminum Foil

Modern vehicles have a structure running horizontally along the outer door skin in place to protect the vehicle's occupants in a side impact accident. Sometimes the space between this structure and the outer skin is filled with something from the factory. Many times it is not. Since the side impact protection structure usually runs along the flimsiest part of the door, pressing Extruded Butyl Rope ino the gap will create a vibration damper in place, where it's most needed. Leave an inch gap every few inches to allow water to pass through unobstructed. I press a strip of aluminum foil into the exposed section of the Extruded Butyl Rope to prevent it from collecting dirt. Also helps to protect the adhesive. A piece of non-stick paper is included with every roll of EBR for pressing it into gaps wihtout sticking to your fingers and pulling itself out.

Apply CLD Tiles™ to the Outer Door Skin

Dodge Ram Door - CLD Tiles™
Dodge Ram Door - Speaker Hole - CLD Tiles™
Pontiac Solstice Door - CLD Tile™
Toyota Prius Plugin Doors - CLD Tiles™

Take a look at How to Apply CLD Tiles™, if you haven't worked with a constrained layer vibration damper before. If you are working from a quote, just use the number of CLD Tiles™ allocated for the outer door skin. If not, height * width of the sheet metal / 240 will give you the number of CLD Tiles™ needed for 25% coverage. As always, weight coverage toward the center of the panel(s).

If you have installed Extruded Butyl Rope or there is a factory treatment joining the side impact beam to the outer skin, consider the areas above and below the side impact beam to be separate panels. Do not use any sort of "tap test" to determine how many CLD Tiles™ to install. Follow the plan. Tap before and after installation to hear the difference.

Go over the CLD Tiles™ with a roller to be sure there are no air bubbles between the adhesive and sheet metal. Gentle pressure is sufficient. Press too hard and you can distort or even crease the sheet metal.

Honda Civic Door Outer Skin - CLD Tile™ Placement

This is what CLD Tile™ placement would look like if the outr door skin was trans[partent and the CLD Tiles™ were yellow. The black areas are steel structures inside the door. The blue patch is the only stock vibration damper on the outer door skin. This is plenty to take the sheet metal from steel drum to non-resonant and solid.

CLD Tile™ on the Inner Door Skin

Dodge Ram Inner Door Skin - CLD Tiles™ 

For most doors I expect a single CLD Tile™, cut into smaller pieces, to be enough vibration damper. Hit the largest areas of sheet metal that isn't reinforced by bends, welds or having something mounted on it.

Barrier built from MLV and CCF on the Inner Door Skin

Dodge Ram Door - Barrier Installed
Honda Civic Door - Barrier Installed
Saturn Sky Door - Barrier Installed
Tesla S Doors - Barrier Installed
Toyota Prius Door - Barrier Installed

Examples of finished inner door skin barriers, ready to have the trim panels reinstalled. There are openings for the trim panel clips and anything else that needs to be flush against the sheet metal. When there is no foam, or other decoupler in the trim panel, CCF has been added to the MLV where it and the trim panel would otherwise make loose contact. As always, any openings in the barrier should be as small as possible.

Critical Points

  • The areas of the trim panel that were in direct contact with the inner skin before treatment should be in direct contact with the inner skin after treatment. 
  • Moving parts must be able to move unimpeded. If there is an actuator rod for the lock knob, make sure it is clear in both positions (gets me all the time).
  • Fit the MLV first. It will not compress. Do not add CCF until the trim panel will fit back on with the MLV in place. If it takes more than a couple of test fittings, consider removing the clips and test fit without them, to avoid wearing out the clips.
  • Be patient. The first door on any car can drive you crazy. Always make that first door one on the passenger side. When you have it fitted, flip it over and see how it lines up with its counterpart on the driver's side. There's a very good chance you'll be able to use the first as a template for the second, with just slight modifications.

You Have to Start Somewhere

Honda Civic Front Door Trim Panel
Trace the Trim Panel onto the MLV
MLV Rough Cut

Tracing the outline of the trim panel is the fastest way to start. It will always give you a starting piece that's a little bigger than you need. A metallic Sharpie or soft pencil are the best options for marking MLV. The blue tape is there to protect the trim panel.


Estimating Materials

Door Measurements

Two sets of measurements should give you all you need to estimate what you’ll need.

You really want to measure the smallest rectangle that will fully enclose the outer skin or trim panel. Many doors aren’t rectangular but it doesn’t pay to estimate that. The area cut away isn’t large enough to be worth much and you do not want to seam pieces of MLV together for the doors – space is tight enough already.

Assuming all measurements are in inches:

Outer skin height * width / 240 gives you the number of tiles needed to cover 25% of the area.

Add 1 or 2 CLD Tiles (depending on size and inner skin configuration), to be cut into smaller pieces, for the inner skin.

Add 1 CLD Tile, to be cut into smaller pieces for the trim panel.

If you’ll be hanging the barrier layers on the inner skin, trim panel height * width / 144 gives you the number of square feet of MLV you’ll need for one door. This number should be pretty good for 3/4" Hydrophobic Melamine Foam as well, depending on the amount of empty, concave space. Use this area, or 1.5 times this area if you will be adding it to the trim panel side of the MLV, for CCF.

If you’ll be hanging the barrier layers on the outer skin, outer skin height * width / 144 is the area for both CCF and MLV.

Allow 2.5 or 3 Velcro® Strips for inner skin barrier layer placement. You’ll want to use somewhat more for outer skin placement.

One roll of Extruded Butyl Rope will be enough for everything but very large vehicles.

If you will just be treating the doors, don’t forget an 8 oz can of HH-66 Vinyl Contact Cement.

Just Treating Your Doors?

It's really important to start with a single piece of MLV for each door. The project is tricky enough when you don't have to worry about seams. MLV comes on a 54" wide roll. I can cut any length (in even inches) you need.

Build Logs for Doors