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Author Topic: Door insulation  (Read 7208 times)

goblinsly

  • Guest
Door insulation
« on: June 26, 2013, 07:33:17 PM »

Hey everyone,
I have been working on my doors for a while now, trying to sound insulate them as well as possible against human speech ( loud talking ).

Base for my doors are 5 cm cheap hollow core doors and i attached on them:
- 5 cm rock wool ( very dense - DP8 )
- 2 cm wood panel
- 2 sheets of drywall
Together about 15 cm ( 5.9 inch )

As you can see the doors are very thick, yet the performance isnt't very well because there were many cracks on the sides - it didnt seal well soo even though the performance of the door was great, sound was still very well heard. Not to mention doors as wide aren't very practical.

I decided to do a project i had in my mind for quite a while, and that is, filling the hollow doors with material i already have at home. What i came up with was filling the doors with 2 sheets of drywall and putting between them 1 cm ( 0.4 inch ) of fiberglass, and the cracks were filled with a mixture of plaster and sand.

Doors weighted 13kg ( 28 pounds ) when they were hollow, now they weight 40kg ( 88 pounds ).





The next thing is to seal all the cracks and after i make the perfect fit, then the time will be for the next step which is putting more drywall on the door. I have several options here soo i want to know what do you think will give me the best result ( again, i only care about speech ). I was thinking of putting 1cm of fiberglass and then over it 2 sheets of drywall. Other options include extra sheet of drywall instead of fiberglass, putting 5cm of very dense rockwool and a sheet of drywall, etc. Right now i have only 2 hinges, i will add another one. I hope you can help me with the right combination of materials to put on the door to get the maximum effect.

The end result should be a bit like this:



On this picture you can see the door i am making right now ( red ) and i have in mind secondary sliding door ( green ), maybe a panel made from wood/drywall that will slide over the door area, hopefully acting like a second door. The gap between both doors wont be very big ( 5-10 cm ) but hopefully will be though to make a difference ( i read that if you divide the same mass of material into 2 doors it will insulate better then if you put all this material into 1 door )

johnbergstromslc

  • Guest
Re: Door insulation
« Reply #1 on: June 26, 2013, 10:35:32 PM »

If you have 88 lb doors, adding more mass is dumb.  They're heavy enough! 

Focus on the seals.

goblinsly

  • Guest
Re: Door insulation
« Reply #2 on: June 27, 2013, 04:38:58 PM »

 I will focus on the seals for now, but when i am done i am pretty sure i will need more mass ... my final goal is that if the person is talking on the other side of the door i won't hear them. I doubt i can do that though since i can hear neighbours talking even over the brick wall.

Randy S

  • Senior Soundproofing Technical Specialist
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Re: Door insulation
« Reply #3 on: June 27, 2013, 05:54:32 PM »

Your already past diminishing point of return on the mass of the door.
I agree with John, focus on the seals..after that the only improvement would be absorption foam on the door or go into a double door system.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

goblinsly

  • Guest
Re: Door insulation
« Reply #4 on: June 27, 2013, 08:45:19 PM »

As you can see on the picture there is a secondary door planed ( sliding door ).

goblinsly

  • Guest
Re: Door insulation
« Reply #5 on: June 27, 2013, 11:49:08 PM »

There is a secondary door ( sliding door ) planed, on the picture you can see it in color green. 

Could you tell me what you mean with diminishing point of return ? Does that mean that adding more drywall to this door won't do much and it would be better adding fiberglass/rockwool/foam for absorbtion ? But adding mass to this second sliding door will be good ? Give me as much info as you can since i will be doing on this doors for the next few days and i really don't want to do too many mistakes.

ps: a while ago i read somewhere that the rockwool must NOT be dense for it to absorb sound better. With this in mind, i really wonder why soo many ppl said that i should buy a high density rockwool ( 80 kg per cubic meter ) to put between 2 sheets of drywall, i mean i didn't add rockwool for mass but for absorbtion, it's mass per price compared to drywall is bad, i am thinking whether it would be better to just put another sheet of drywall there ...

jhbrandt

  • Guest
Re: Door insulation
« Reply #6 on: July 11, 2013, 06:26:24 AM »

Gob,

It depends on the purpose/use and position of the rock wool or absorption material as to what density will be of best effect. As already recommended, and I think I commented on your post in GS, you must make sure that the door seals - not well, but perfectly. ;) The 'aquarium' analogy is appropriate here.

Good luck!

I think next time, you should think seriously about constructing a proper 'sand-filled' door with trunk rubber seals. :D
No bowing, no warp, rock solid.. and NO SOUND.

Cheers,
John

goblinsly

  • Guest
Re: Door insulation
« Reply #7 on: July 11, 2013, 11:42:47 AM »

Next time i will make proper rock solid doors for sure.

About warping, i know i cant completely remove it but maybe i can repair it at least a bit .. maybe with some metal plates across diagonal ? If i make an x with something solid, it should help a bit ....

goblinsly

  • Guest
Re: Door insulation
« Reply #8 on: July 15, 2013, 09:12:26 PM »

Any ideas on how to install the sliding doors ?

jhbrandt

  • Guest
Re: Door insulation
« Reply #9 on: July 15, 2013, 10:29:17 PM »

Gob,

I don't know. I design a lot of things, but I have never attempted to custom a slider. Manufacturers of normal, regular sliding glass doors go through hundreds of prototypes to get to a premium door with good seals.

If my client is insisting on having a slider, I will usually direct him to one of the premium sound-proof door companies that I know have good products. And, holy cow!, they're not cheap. LOL! - But there is a reason for that. These things have testing data and they are guaranteed to perform. That's the only way that I will specify them.

There are times when you can do a bit better by DIY, but often it will cost just as much if not more to obtain the same spec or quality of a professional purchase. DIY is fun because we learn something in the process and that experience is often priceless. This is one of those times that you really should make sure which it is. If it is only the cost / budget, then you would be better off purchasing a normal vinyl slider for patios. It will offer you more STL than a DIY effort. I can almost guarantee that. I think you can get them pretty cheap at HD or Lowes.

Good luck!

Cheers,
John

Randy S

  • Senior Soundproofing Technical Specialist
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Re: Door insulation
« Reply #10 on: July 15, 2013, 11:55:22 PM »

We normally just do a double slider with a 2" or greater air gap.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

goblinsly

  • Guest
Re: Door insulation
« Reply #11 on: July 16, 2013, 09:23:45 AM »

Thinking about it, maybe it would be easier to just make a normal door with hinges and 2 wings  .. i think it would be cheaper to make and would seal better ... i would put another layer of drywall on it and make sure it overlaps in the middle ..  This door would be as a backup since i already have the main door ... i would just use them when the need for insulation would be greater ...






This is how it would look like ... soo what do you think ? Should i go for this instead of the sliding doors ? I will have to move the light switches ... and offcourse the door wings wont be the same size as i only have about 30cm of space on the right since there is another door there.

goblinsly

  • Guest
Re: Door insulation
« Reply #12 on: July 29, 2013, 06:25:58 PM »

I decided to put some black hardwood over the door to make it look better and i have to say i am really happy with the result. The pictures dont do justice to the door, it really looks good.

goblinsly

  • Guest
Re: Door insulation
« Reply #13 on: August 25, 2013, 02:56:58 PM »

I will put 2 sheets of hardwood on the door, to make it more solid and to make it look prettier ... i think it would help with insulation also since hardwood is quite heavy. Now what i have been wondering is .... should i put that 2 sheets of hardwood directly on the door or should i put about 1 cm (0.4 inch) of fiberglass between them. Was thinking this would add some absorbtion and also somehow lessen the sound travel from door to the hardwood. Or would it be better to spend that extra 1cm on another sheet of drywall or something like that ..

ps: the reason i am asking you this is that if you ever saw the door in music schools, it has some kind of foam on both sides of the door. I dont think the reason for that is to make the sound better but to insulate. How much does that foam on doors help ? I guess it must help somewhat, why else would they put it on the solid doors ?

goblinsly

  • Guest
Re: Door insulation
« Reply #14 on: September 09, 2013, 02:50:55 PM »

Sealing is 50% done and i am happy with the result soo far. Here are some pictures of the work done today. It doesn't look good yet since soo far i was only doing on sound insulation, once that is done i will sand and repaint the whole thing ( and add hardwood floor :3 ).

Here are some pictures:














You can see where i added wood to the frame to make an extra seal between the door and the frame. If necesary i plan to make an extra seal or two. Usualy 1 seal would be enough but sadly the door and the frame isnt completely even soo this is the best that can be done. Please comment the work done soo far, advices also welcome. :)