5/8 gypsum board vs MDF

I cannot find the answer to this question. Maybe someone here can help... Are there any advantages to using MDF in conjunction with sheetrock when building an acoustical wall other than these materials having different resonant frequencies? An example would be: MDF > Greenglue > 5/8 sheetrock. Would this maybe give me a higher STC rating than if I just used 2 layers of the sheetrock with the greenglue? What do you guys think of MDF overall? thanks, Tony

The real downside to MDF is it can't be cut as easily as Gypsum. And with the extensive use of electric saws comes the increased mess and dust inhalation risks...

I agree but is it sonically valid- or better yet does it improve things (in the case of my application)

I agree but is it sonically valid- or better yet does it improve things (in the case of my application)

it depends on the thickness of the mdf panel. a 3/4 inch mdf panel is far heavier than a 5/8th gypsum, so it would yield better results. remember that mdf is flammable, so it would best be sandwiched in between gypsum layers.

PhilR wrote:

The real downside to MDF is it can't be cut as easily as Gypsum. And with the extensive use of electric saws comes the increased mess and dust inhalation risks...

What? :) I disagree, the real downside of medium density fiber is that a 3/4 inch 4X8 sheet is so heavy, when I picked one up once, I lost two inches in height and my arms gained an inch!

3/4" MDF is about 3.25lb/sqft. 5/8" drywall is about 2.2lb/sqft - depending on where you live one or the other may be cheaper... if you can double up the 5/8" you have more density... for example, by me, MDF is about $23 per panel whereas a pair of paperless 5/8" drywall is $13 and regular 5/8 is about $10 a pair so I can get way more density per $ with drywall (except labor cost...) MDF or drywall dust (like most dust) isn't great to inhale... http://www.usg.com/USG_Marketing_Conten ... 00-001.pdf http://www.flakeboard.com/msds/Flakeboa ... F_MSDS.pdf

Right as rain you are Glenn. Properly suited to work with this product, safety glasses w/side shields and personal dust respirator on....work with a full sheet or two by yerself and tell me which one causes you the most distress the quickest:)

For me (personally) The only reason I would substitute MDF as a sub layer is it would make it simpler to screw and attach acoustic treatments wherever you wanted as opposed to finding studs under an 1.25 of sheetrock.

xSpace wrote:

I disagree, the real downside of medium density fiber is that a 3/4 inch 4X8 sheet is so heavy, when I picked one up once, I lost two inches in height and my arms gained an inch!

:mrgreen: LOL Brien, how many MDF boards did you pick up already? Trying to picture how you look like now. :twisted: There is another species with these kind of ratios as well. +++++++++++++++++++++++++++++++++++++++++++++++ Just theoretically: Normally Gypsum board is somewhat better than fibre board with the same mass, since the latter has a broader coincidence area (insulation plateau). But it's not that important that one shouldn't use MDF in combination with gypsum board for practical purposes (hanging, screwing stuff).

what is the holding power of MDF versus plywood where you're using it as a backing to screw into.

Eric_Desart wrote:

xSpace wrote:

I disagree, the real downside of medium density fiber is that a 3/4 inch 4X8 sheet is so heavy, when I picked one up once, I lost two inches in height and my arms gained an inch!

:mrgreen: LOL Brien, how many MDF boards did you pick up already? Trying to picture how you look like now. :twisted: There is another species with these kind of ratios as well.

That mental snapshot does seem to be the view many have of the construction trade:) Or is that just me,

Guys, Quick question: Round here I'm thinking what we used to call "particle board" is actually MDF? Is this the same stuff? We used to make bass and pa cabs with it years ago. It's also used for countertops etc. Thanks

No sir, they are two separate building products. Wiki: Particle board Wiki: Medium Density fiber

Ah-ha! Thank you for the clarification. I'm familiar with that stuff too but I think we just called it plain old fiberboard. Medium Density FIBERBOARD...Duh!

Thank you all for the responses. I can get 3/4 MDF 4x8 sheets for about $12.00 through a friend of mine that has a cabinet making business. Yes- MDF is more of a pain to work with due to its weight and yes it would be better in the sense of not dealing with studs etc… for panels and such. My question is--- SONICALLY does MDF have any advantages over 5/8 sheetrock?

The question has allready been answered - but (to save you the trouble of looking up the answer on the previous page) here: If you can buy it cheap enough to compare with drywall - then you get added mass - and from that perspective it will increase (very slightly) the TL value of your wall assembly. Rod

Thanks for clarifying for me Rod. Tony