The rear of the van is probably the best it will be and only suffers from occasional resonance due to it still being a large empty space. The addition of furniture, soft furnishings and other items in the rear will reduce the expanse of flat panels which should reduce noise generation and reverberation substantially. I also plan to have a fitted but removable carpet made with integrated underlay.
So, the focus at present turns to the front of the van and at this point, the front doors. Doing a simple tap resonance test tells me that the current doors are going to be highly active and, given their large flat nature, will be pretty efficient at transmitting any vibration input that they have. I decided to put a stop to this with a 2 step approach
1. Increase the mass of the panel to put the resonant frequency out of range and to employ the use of a material that will absorb some of the energy in the process (Bitumen flashing tape!)
2. Provide heat and sound insulation by using a synthetic wool (loft insulation)
This is a pretty easy job to do the only tools you will need is a torx driver, philips screwdriver and trim removal tool. First thing to do is to remove the door trim.
1. Pull up and off the handle cover
2. Unscrew the 2 philips screws holding the handle assembly to the door frame (no need to remove the handle)
3. Undo the 4 torx screws (1 in the middle of the door and 3 at the bottom of the door)
4. Remove the window winder by popping the spacer in the opposite direction of the handle
5. Prize carefully the pop fixings and then lift the door card up and off (Remember to unhook the door catch and disconnect any wiring you may have)
Next step was to attach the wool to the door so that I could sandwich it between the door card and the door. I used a very sticky waterproof clear tape used for repairing roofs to attach the wool.
The difference is clear and I only have the cab floor, bonnet and behind the dashboard to do to make my T5 the quietest there is!