MDF For Wall Layers

Besides being heavy and harder to cut, any advantages/disadvantages to using MDF instead of Drywall? Would I get better STC with MDF?

Well is way expensive.

MDF is actually quite soft... especially when it gets wet. I'd use MDF/Plywood or OSB as a base layer behind gypsum. (actually, I used OSB in my build.) But if it's an either/or situation... used the gypsum for cost factor... LOTS cheaper mass for the money.

Yes it is more expensive, but would be worth it if a higher STC would result. Anyone have the STC ratings for MDF and plywood compared to gypsum? I can't seem to find any. The only reason I'm considering this is that I had a room about 10 years ago that we constructed using a sandwich of MDF/soundboard/MDF/T&G pine that worked excellently. We mainly used it as we needed something we could disassemble at a later date, but it ended up being a great sounding room with excellent isolation. Since I'm building in a space that has offices above me, I'm looking for the best possible isolation bang for the buck. If it's just as good to use an extra gypsum layer (3) I'd definitely opt for that.

The sound isolation difference between MDF and gypsum is not very significant. The advantage of MDF as part of a wall sandwich is that it permits you nail or screw in anywhere on teh wall for hanging objects. Andre

What Andre and Max said......... no advantage. You could have acheived everything you did in the other room just by using drywall - the sound board is virtually useless for isolation as well, especially in the middle of a sandwich. You might gain a tiny TINY bit by placing it directly over the studs - but nothing in between sheets of structural boards. There is no tested data that I am aware of for determining the value of the sound board. Thre fact that the company makes a claim and then stead-fastly refuses to post any test data makes me very sure that posted test results would NOT be in their favor - yet if they did not test they have no basis for making a claim that the product has value. Smoke and Mirrors - it's all Smoke and Mirrors. Rod

rod gervais wrote:

There is no tested data that I am aware of for determining the value of the sound board. Thre fact that the company makes a claim and then stead-fastly refuses to post any test data makes me very sure that posted test results would NOT be in their favor - yet if they did not test they have no basis for making a claim that the product has value.

Aside from seeing no acoustical reason why soundboard would be better, the lack of data on the makers' websites makes me even more leary of the product. The only testing that I am aware that might be soundboard is teh series of wall assemblies in IR 761 using "fibre board." Unfortunately soundboard is a tradename, and I am not certain if soundbaord is the same as fibre board. FYI the test results are on pdf pages 252 and 253. Andre

Very good then, drywall it is! Much easier to work with especially overhead. I'll not bother with the soundboard this time around either. Thanks for the info.

We tested soundboard many times. At least one manufacturer recommends installing the drywall with screws into the soundboard and not the stud... Like installing to cardboard. When screws are set through the soundboard into studs, the performance is very mediocre. Too dense to decouple (screws notwithstanding) and too dense for any beneficial absorption. Not bad as an underlayment. I'd suggest as other have to use a base layer of plywood or OSB, then layers of drywall.

AVare wrote:

The sound isolation difference between MDF and gypsum is not very significant. The advantage of MDF as part of a wall sandwich is that it permits you nail or screw in anywhere on teh wall for hanging objects. Andre

New thoughts on the MDF subject. Andre - I saw your Gearslutz post and links to Malcolm Chisholm's Studio Design pages. This series of articles that appeared in Mix Magazine some years ago was instrumental in designs I implemented in the construction of a mixing/tracking room I built back in the 90's. http://malcolm.bignoisybug.com/rsdp/control.txt One of the things I garnered from this article was the idea to use dense, stiff wall materials such as his suggestion of using particle board. I'm sure as has been stated here, the STC figures are similar to gypsum, but in re-reading the articles on his site he points out that STC ratings are an average rating across the frequency spectrum. If I'm correct in my understanding, he points out that there is a big performance difference with particle board in transmission loss of lower bass frequencies. Just thought I'd see what other comments you and others might have regarding Malcolm's design. I'm not a studio designer per say, but I've built 4 of them for myself with varying results. My last two both worked really well, one that had serious isolation issues where I used particle board and another that didn't where I used multi gypsum layers. My new rooms are in a commercial building where isolation, especially from second floor offices is a big concern. Since the main room I will be building out is a proposed tracking space where I'll be recording all kinds of instruments from drums to vocals and strings, I need to really focus on the isolation issues, especially the bass. Obviously, I want to come up with the best solutions within my budget and space limitations. Hence my MDF questions. Thanks BTW for those links to Malcolm's site. I got a lot of great info out of his articles with the re-read as I did back in the 90's when they first surfaced.

It's really about the mass, not so much the densities. Particleboard is dense, and so tends to build nice massive partitions. MDF does as well, as does drywall. Personally, if I was looking to have a nail base in a wall or ceiling I'd be looking at plywood or OSB. They hold screws much better than particleboard or MDF

specialkm wrote:

AVare wrote:

The sound isolation difference between MDF and gypsum is not very significant. The advantage of MDF as part of a wall sandwich is that it permits you nail or screw in anywhere on teh wall for hanging objects. Andre

New thoughts on the MDF subject. Andre - I saw your Gear Page post and links to Malcolm Chisholm's Studio Design pages. This series of articles that appeared in Mix Magazine some years ago was instrumental in designs I implemented in the construction of a mixing/tracking room I built back in the 90's. I'm sure as has been stated here, the STC figures are similar to gypsum, but in re-reading the articles on his site he points out that STC ratings are an average rating across the frequency spectrum. If I'm correct in my understanding, he points out that there is a big performance difference with particle board in transmission loss of lower bass frequencies. Just thought I'd see what other comments you and others might have regarding Malcolm's design.

You are welcome for the links to Malcolm's great writings. STC is innapropriate for studios, especially in the low end. Since Malcolm wrote those articles, thanks to the miracle of the internet, test data on partitions for TL down to 50 HZ is readily available. The NRC-IRC 1R761 and similar documents with test data for HUNDREDS of partitions is available. Those combined with physics and price guide the advice given by professional acoustics people. Keep absorbing the knowledge and you will end up a fantastic facility for your budget and restraints. Read Naethoven;s thread at gearsluyz as an example of what can be done with minimal budget and great knowledge. Andre

Ted White wrote:

It's really about the mass, not so much the densities. Particleboard is dense, and so tends to build nice massive partitions. MDF does as well, as does drywall. Personally, if I was looking to have a nail base in a wall or ceiling I'd be looking at plywood or OSB. They hold screws much better than particleboard or MDF

I may be in error, but aren't MDF and particleboard basically the same thing? If not, I may erroneously referring to my use of particleboard as MDF.

AVare wrote:

specialkm wrote:

AVare wrote:

Read Naethoven;s thread at gearsluyz as an example of what can be done with minimal budget and great knowledge. Andre

Thanks, I'll search that out. km

Particleboard and MDF are similar. Finer lumber particles in MDF. Smoother when cut. Particleboard has larger visible particles. Not as smooth when cut and sanded. Both can hold screws but more care needs to be taken, such as pre-drilling