MDF instead of drywall? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 18 Old 05-28-2013, 09:09 PM - Thread Starter
Member
 
audio4u2's Avatar
 
Join Date: Jul 2007
Posts: 76
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Guys,

Would there be any reason 3/4" MDF would not work as well as 5/8" drywall. I am working on remodeling an existing theater of mine just so happen to have a bunch of MDF left over from another project.

The material would be to add a second layer to all existing walls. The ceiling has already been treated with double sheet rock.

It would also act has great backer for now columns we will be adding.

Thank you

Tyler
audio4u2 is offline  
Sponsored Links
Advertisement
 
post #2 of 18 Old 05-28-2013, 09:28 PM
AVS Special Member
 
Elill's Avatar
 
Join Date: Dec 2007
Location: Sydney, Australia
Posts: 1,445
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 19
MDF doesn't like moisture of any kind, its not suited to this type of application. Whilst you'd be using it as a second layer I'd personally not do it.

Better off with a structural ply or OSB (as a first layer and drywall over the top).

Peter the Greek


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Redefining snail pace construction
"what is worth knowing is difficult to learn"

Elill is online now  
post #3 of 18 Old 05-29-2013, 01:46 AM
Senior Member
 
psychdoc's Avatar
 
Join Date: Jul 2005
Location: central Oahu, Hawaii
Posts: 453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 70
Just to throw out a different opinion..... when putting together my theater the engineers at Kinetics suggested using MDF instead of ply due to the better resonance profile. There is a reason why many speakers are often made of MDF. Check my thread out to see details of how I went crazy with MDF ( http://www.avsforum.com/t/1406831/hawaii-home-theater-construction/120 ). There are two downsides.... it hates water and should not be used as an outer layer that can possibly get wet and the dust when cutting it.... wear a mask! I used it everywhere and it worked perfectly for me. I used a billion screws to ensure no area was too stressed. Absolutely no downsides in my book and it works GREAT! Just make sure you do it right as this stuff will add serious mass to the soundproofing equation. You will likely get more opinions. Do your own research and decide what is best for you. Good luck! smile.gif


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
psychdoc is offline  
post #4 of 18 Old 05-29-2013, 08:50 AM
Advanced Member
 
BroncoSport's Avatar
 
Join Date: Feb 2005
Location: Wichita, KS
Posts: 757
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 20
....and MDF has NO fire protection (if that matters to you). I believe that this topic has been brushed before and it seems that the difference between 5/8" drywall and 3/4" MDF is very similar, but the ease of install, water resistance and shear weight makes the MDF a less than enjoyable option. IMO

My Build Thread:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
BroncoSport is offline  
post #5 of 18 Old 05-29-2013, 05:23 PM
Senior Member
 
acras13's Avatar
 
Join Date: Mar 2011
Location: Los Angeles , CA
Posts: 242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 13
Quote:
Originally Posted by BroncoSport View Post

....and MDF has NO fire protection (if that matters to you). I believe that this topic has been brushed before and it seems that the difference between 5/8" drywall and 3/4" MDF is very similar, but the ease of install, water resistance and shear weight makes the MDF a less than enjoyable option. IMO

While the cost and difficulty of installing MDF might offset any advantages it has over drywall , I can't believe that theres no real difference acoustically between MDF and 5/8" drywall . I don't have any scientific data , but how many speaker enclosures do you see made out of drywall ? Drywall has more flex than MDF and MDF is denser than gypsum .

“Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”---Mark Twain
acras13 is offline  
post #6 of 18 Old 05-29-2013, 05:49 PM
Senior Member
 
psychdoc's Avatar
 
Join Date: Jul 2005
Location: central Oahu, Hawaii
Posts: 453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 70
If I can follow up on acras, if I can install this stuff everywhere, the "difficulty" factor should be probably taken out of the equation. wink.gif I believe he is also correct regarding the soundproofing effect of MDF vs drywall. Having put up both 5/8" drywall AND MDF..... there is no way I believe the two are in the same league. Just the weight alone should say the two are not the same. For me, I'm glad I put both the MDF and drywall up.... my HT is like a blackhole for sound (nothing escapes). Just saying.....

On the bright side, once the MDF goes up, getting attachment points everywhere and anywhere for screws is quite the convenience.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
psychdoc is offline  
post #7 of 18 Old 05-29-2013, 07:05 PM
AVS Special Member
 
Elill's Avatar
 
Join Date: Dec 2007
Location: Sydney, Australia
Posts: 1,445
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 19
Quote:
Originally Posted by psychdoc View Post

On the bright side, once the MDF goes up, getting attachment points everywhere and anywhere for screws is quite the convenience.

MDF doesn't like screws being done twice......just saying.

On the other stuff:

MDF (in Australia at any rate) is about 700kgs/m^3

The more dense fire rated dry wall sheets here are 1000kgs/m^3

Flex isn't a bad thing when it comes to walls either

IMO think you'd be insane to use mdf, I've renovated too many places that have used it for one reason or another and in a tropical (humid) environment it just acts like a sponge, even in "dry" well ventilated areas it can attract mould

Peter the Greek


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Redefining snail pace construction
"what is worth knowing is difficult to learn"

Elill is online now  
post #8 of 18 Old 05-29-2013, 09:16 PM
Senior Member
 
acras13's Avatar
 
Join Date: Mar 2011
Location: Los Angeles , CA
Posts: 242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 13
Quote:
Originally Posted by psychdoc View Post

If I can follow up on acras, if I can install this stuff everywhere, the "difficulty" factor should be probably taken out of the equation. wink.gif I believe he is also correct regarding the soundproofing effect of MDF vs drywall. Having put up both 5/8" drywall AND MDF..... there is no way I believe the two are in the same league. Just the weight alone should say the two are not the same. For me, I'm glad I put both the MDF and drywall up.... my HT is like a blackhole for sound (nothing escapes). Just saying.....

On the bright side, once the MDF goes up, getting attachment points everywhere and anywhere for screws is quite the convenience.

Looks like I'll be bugging you here too Psych. You said difficulty of installation should be taken out of the equation , then you mention the weight difference , didn't you mention in your build thread how much "fun" you had with the MDF on your ceiling?wink.gif The other factor is that you can measure and cut the drywall right where you are with a utility knife , the MDF needs a saw which for many DIY'ers greatly increases the difficulty , and danger . Not speaking about you of course , since I've seen the toys you're buying to start your cabinetry business when you retire from your day job...

Elil , mounting the MDF it won't matter how it takes screws as the screw's bite in the stud is what will be holding it in place , and if I was doing the installation , I would attach the drywall with correspondingly longer screws into the studs as well , not just into the MDF . As to you're density examples , I said I wasn't using science , so I utterly reject those strange characters you posted . My statement was based on the fact that I can dent drywall far easier than I can dent MDF , I believe that can be extrapolated into some sort of science but its beyond me. In a home theater I believe that the flex is a bad thing for soundproofing . From what I've read since sound is vibration , you add mass to try to minimize the vibration being transmitted through the structure . Psychdoc knows more about it than I do ( as do quite a lot of people) because he installed his MDF following a sound engineers specs . Of course your mass examples are interesting , if the products we have in the U.S. have similar mass then just based on mass , drywall would be superior , unless the structural rigidity factors into it , in which case ( again , no science) the MDF is superior. The damp weather performance to me is a draw , if you're not using water repellent drywall , both will be compromised by water and humidity and be subject to mold and mildew .

“Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”---Mark Twain
acras13 is offline  
post #9 of 18 Old 05-29-2013, 09:56 PM - Thread Starter
Member
 
audio4u2's Avatar
 
Join Date: Jul 2007
Posts: 76
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Thanks for the input. I am torn between still using the MDF. It does make a great base for my proposed columns. I will be building the columns out of MDF and by having MDF as the base I can glue the columns directly to the wall.

Also if I do my math right I can basically eliminate any drywall work in the room itself. The house is finished and drywall is messy.

Not worried about moisture or fire rating as the room is already complete, remember I am using this as my second layer. If I where building from scratch 2 layers of 5/8 drywall would be the only way to go.

Heck not sure what to do!!!

Cheers

Tyler
audio4u2 is offline  
post #10 of 18 Old 05-29-2013, 11:02 PM
AVS Special Member
 
Elill's Avatar
 
Join Date: Dec 2007
Location: Sydney, Australia
Posts: 1,445
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 19
Quote:
Originally Posted by acras13 View Post

As to you're density examples , I said I wasn't using science , so I utterly reject those strange characters you posted .

Its widely accepted that you want:
- isolation (clips and channel or room in room)
- mass (heaviest board you can put on a wall)
- damping (green glue etc)

Drywall is heavier per cubic meter than mdf i.e. has more mass per the same size sheet than mdf
Quote:
Originally Posted by acras13 View Post

In a home theater I believe that the flex is a bad thing for soundproofing .

If you're isolated it doesn't matter i.e. the vibrations aren't being transferred into another part of the building. Flex is good - think about why people people dont just build block concrete walls, floor and ceiling and just stick some speakers in it - the bass will be horrid. A flexible wall provides some (albeit limited) bass trapping

Peter the Greek


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Redefining snail pace construction
"what is worth knowing is difficult to learn"

Elill is online now  
post #11 of 18 Old 05-29-2013, 11:04 PM
Senior Member
 
acras13's Avatar
 
Join Date: Mar 2011
Location: Los Angeles , CA
Posts: 242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 13
That does change things a bit . How are you planning on finishing the room out ? What are your plans for all the joints , just leave them as is , or smoothing/ filling the joints then painting? All those cuts are going to have to be pretty precise or things are going to be looking sloppy , and I don't know if drywall mud will work very well in this application to fill the imperfections , I'd be afraid that there wasn't enough " bite" on the MDF. Having said that , GO FOR IT !!! Just remember to take a lot of pictures of your progress , I want to see how it works out .

“Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”---Mark Twain
acras13 is offline  
post #12 of 18 Old 05-30-2013, 12:35 AM
Senior Member
 
psychdoc's Avatar
 
Join Date: Jul 2005
Location: central Oahu, Hawaii
Posts: 453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 70
Elill... you didn't mention one item that changes the equation. Drywall might be more dense per any cubic measurement but with MDF you'll likely buy a 3/4" sheet. So, in that respect you are talking apples to oranges. A piece of 5/8" drywall is not better than 3/4" MDF. The weight difference alone is somewhere around 30% which directly impacts the "mass" portion of the equation. If, however, you want to buy 5/8" MDF then I am in agreement with you.... just stay with drywall.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
psychdoc is offline  
post #13 of 18 Old 05-30-2013, 05:54 AM
Member
 
xjagox's Avatar
 
Join Date: Aug 2005
Location: Maryland
Posts: 183
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 13
3/4 MDF is about 3x the cost of 5/8 DW around here. One 3/4 MDF+5/8 DW (1.375" total) would be ~$45 per 4x8. Triple 5/8 DW (1.875" total) would be ~ $30 and would be thicker, more mass, and easier to work with.

I just can't see the point in using MDF given the downsides.
Daniel Smith likes this.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
xjagox is offline  
post #14 of 18 Old 05-30-2013, 05:58 AM
AVS Special Member
 
Trepidati0n's Avatar
 
Join Date: Nov 2003
Posts: 1,090
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 91
You could sell the MDF at a profit and get drywall?

I must be guilty because people say I am guilty because they chose to call me guilty because they refuse to see the truth. Much easier to be part of the mob..
Trepidati0n is offline  
post #15 of 18 Old 05-30-2013, 08:02 AM
Senior Member
 
acras13's Avatar
 
Join Date: Mar 2011
Location: Los Angeles , CA
Posts: 242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 13
Quote:
Originally Posted by xjagox View Post

3/4 MDF is about 3x the cost of 5/8 DW around here. One 3/4 MDF+5/8 DW (1.375" total) would be ~$45 per 4x8. Triple 5/8 DW (1.875" total) would be ~ $30 and would be thicker, more mass, and easier to work with.

I just can't see the point in using MDF given the downsides.


You're forgetting that he already has the mdf from previous projects so the cost isn't a factor for him.

Quote:
Originally Posted by Trepidati0n View Post

You could sell the MDF at a profit and get drywall?

I can't imagine the fun of dealing with the screwballs that would respond to the craigslist add for MDF. I've sold 5 vehicle in the last 6 months or so and every one of my posts has gotten dozens of people asking if I would take 1/8 - 1/2 of my asking price before I get someone sane. I'm imagining people offering 5 cents a sheet, or trying to charge to remove it from his place. Then the guy that says he'll pay your price will show up on a bicycle to haul it home because he didn't think about how to carry it.

“Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”---Mark Twain
acras13 is offline  
post #16 of 18 Old 05-30-2013, 09:02 AM - Thread Starter
Member
 
audio4u2's Avatar
 
Join Date: Jul 2007
Posts: 76
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by acras13 View Post

That does change things a bit . How are you planning on finishing the room out ? What are your plans for all the joints , just leave them as is , or smoothing/ filling the joints then painting? All those cuts are going to have to be pretty precise or things are going to be looking sloppy , and I don't know if drywall mud will work very well in this application to fill the imperfections , I'd be afraid that there wasn't enough " bite" on the MDF. Having said that , GO FOR IT !!! Just remember to take a lot of pictures of your progress , I want to see how it works out .

The joints could be placed behind the columns or at the chair rail height. Drywall mud does not work well with MDF, Autobody filler does!!

Thanks,

Tyler
audio4u2 is offline  
post #17 of 18 Old 05-30-2013, 09:03 AM - Thread Starter
Member
 
audio4u2's Avatar
 
Join Date: Jul 2007
Posts: 76
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by acras13 View Post

You're forgetting that he already has the mdf from previous projects so the cost isn't a factor for him.
I can't imagine the fun of dealing with the screwballs that would respond to the craigslist add for MDF. I've sold 5 vehicle in the last 6 months or so and every one of my posts has gotten dozens of people asking if I would take 1/8 - 1/2 of my asking price before I get someone sane. I'm imagining people offering 5 cents a sheet, or trying to charge to remove it from his place. Then the guy that says he'll pay your price will show up on a bicycle to haul it home because he didn't think about how to carry it.

This is to funny. I sell on Craiglist and so true. I also ride bikes so got a good chuckle out of that!

Thanks,

Tyler
audio4u2 is offline  
post #18 of 18 Old 05-30-2013, 10:37 AM
Senior Member
 
acras13's Avatar
 
Join Date: Mar 2011
Location: Los Angeles , CA
Posts: 242
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 13
Quote:
Originally Posted by audio4u2 View Post

This is to funny. I sell on Craiglist and so true. I also ride bikes so got a good chuckle out of that!

Thanks,

Tyler

This is for you Tyler I'm sure you'll get a kick out of it. I had this listed a while back, unfortunately I deleted the responses, but I literally had people reply with " I'll pay $250. AND... Pick it up!! Because normally delivery comes with low balling someone on their item.
(This is for amusement only, the item has been sold, I am not advertising AT ALL!!)

2004 Foes Fly - $1200 (Redondo Beach)
I have a 2004 Foes fly frame is XL size (I'm 6'4 ,perfect fit , can probably work for 5'10" up)
It has adjustable rear travel 6.75" -8" , adjustable head angle , floating rear brake
Truvativ hussfelt cranks , 2 ring and bash guard
E thirteen chainguide
Azonic pedals
Shimano dual piston xt hyd. brakes w/dangerboy 2 finger levers and braided stainless steel lines
Fox vanilla rc shock w/600x2.8 spring
telescoping seatpost , 2 piece , allows better range of adjustment with the interrupted seatpost design
Brand new Marzocchi 55 rv fork , never ridden off road
Sram x 9 shifters , front and rear
Sram x9 rear derailler
Sram x7 front
Nokian nbx 2.5 tires
Power tools wheelset , no fancy name , but these have held up better than some $1500 wheelsets
asking $1200 firm . Cash , no paypal , no third party checks , no offers of your grandmother baking me a lifetime of cookies , just cash . Thanks for looking
Location: Redondo Beach
it's NOT ok to contact this poster with services or other commercial interests


Great idea hiding all the joints behind trim, and thanks for the bondo tip.

“Loyalty to country ALWAYS. Loyalty to government, when it deserves it.”---Mark Twain
acras13 is offline  
Reply Dedicated Theater Design & Construction

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off