Door Improvement Question

I installed a 1 3/4" thick door made out of MDF with a birch veneer. I installed a seal kit including drop-down seal from Zero International. The space between the door frame and rough opening is insulated and well caulked. I achieved an improvement of about 30 dB which I THINK is close to par for this setup. I was a little disappointed though once I was able to hear what a 30 dB drop actually SOUNDS like. I would like to achieve more. I have plans in the future to install a second door about a foot away. However, in the meantime I would like to see if I can improve what I have. Here is what I am wondering: I have some 1 lb/sq ftMLV. I was thinking of putting the MLV on the outside of the door and then maybe a thin sheet of wood over that. However, because of the door seals I will not be able to install the MLV all the way to the edges. In other words there will be a thin strip (maybe 1/8th inch) around the edges of the door that will not be covered. Will this improve my door at all or is it a complete waste of time? Keeping in mind that the door and seals are already installed does anyone have any better suggestions? Aside from the MLV I also have a couple of tubes of Green Glue I could use for door improvement.

bdurst wrote:

Keeping in mind that the door and seals are already installed does anyone have any better suggestions? Aside from the MLV I also have a couple of tubes of Green Glue I could use for door improvement.

BD, green glue will help more than the MLV - 8 pound lead would be even better yet.......... BUT - you are going to have to add another level of weatherstripping or it isn't rsally going to amount to a whole lot.......... although the door is a weak point - the weakest points are the seals - I don't see where there's a problem - let the doo seals not just like it does - add 3/" to the inner face (plus GG - and then add - over and inside of the existing weatherstripping - another run of eweaktherstripping/ Relocate the drop seal to the inside face of the new plywoiod......... what's so difficult about that? Sincerely, Rod

I'm in a similar boat, except I haven't put in any door seals yet, and I have 2 doors seperated by about 8-9 inches. The reduction in sound is not terrific. It's pretty clear in my installation that high frequency is getting around from the lack of seals...an easy fix. But low frequencies are getting through I think because of a coincidence dip, and the lack of insulation in the door cavities. My plan is to install an MDF sheet to each inner door face (sandwiched to the door w green glue in between), and attach 2" 703 (fabric wrapped) to the MDF. My hope is that the additional mass will improve TL, and that the 703 will damp the cavity resonance. I strongly beleive that you need insulation between the doors to improve the STC and TL. Cheers Kris

I am coming to the end of my build and I too had the "That door still lets a lot of sound out" feeling.... BUT I added two VERY thin layers (4-5mm) of wood.. brazilian something - hard wood ply..) with 70%+ of green glue between both layers.. I also added some standards (cost £7.50) rubber draught stops (screwed to the inner side of the door) and the difference was MASSIVE! I think that the combination of green glue and more seals is a winner... Cheers Geoff

Thanks all for your ideas. They are much appreciated.