Will this floor work?

[j0nas]

Hi,

I have a question about floor design for my new (first) home studio. The studio will be built in a basement. And as with all basements (at least here in Sweden), they very often have humidity problems. If I put wood (battens?) directly against the concrete basement floor, it'll get mouldy;-(

I found a type of floor, Nivell System (see link below), which is designed for building basement sub floors. It lets the concrete to "breathe" by a layer of air (see below link for pictures).

Will this layer of air between the basement floor and the sub floor cause resonance?

Links:
http://www.nivellsystem.com/engelsk/

More pictures (swedish text):
http://www.nivellsystem.se/sv_komponenter.htm
http://www.nivellsystem.se/sv_montering.htm


Thanks,
Jonas Sundgren

[laptoppop]

Originally posted by j0nas

Will this layer of air between the basement floor and the sub floor cause resonance?

Sorry, but I think the answer is yes. Chamber with air pretty much always equals some resonance, unless it is seperated from the studio with something else that absorbs/blocks the sound transmission.

Now, of course, the question becomes what the frequency of resonance would be, and if that frequency would affect your recording. My intuition says that it could be very problemmatic, but I don't know for sure.

-lee-

[ola]

Not necessarily. It'll just be a floated floor, used in many studia. What you need is insulation below the floor and narrow spacing between the jousts to stop the floor from resonating. Check this out

If you ensure good ventilation below the floor, you should be fine. However, if your humidity problems are that big, consult with a proffesional builder before you go ahead and build. Maybe you should look into fixing the humidity problem first if you're planning on having sensitive equipment in the room.

Also, that nivell system looks rather under dimensioned. Very far between the joist, which also are quite thin.

[swedish]
Jonas, jag är gymnasiebyggnadsingenjör och hjälper dig gärna med ett grundförslag som du kan ta med dig till ett proffs som kan ge sitt utlåtande vad det gäller mögelrisk. Skicka en enkel ritning på rummet så skissar jag ett golvregelverk.
[/swedish]

/Ola
ola.franzen@goyada.com

[laptoppop]

Originally posted by ola
Not necessarily. It'll just be a floated floor, used in many studia. What you need is insulation below the floor and narrow spacing between the jousts to stop the floor from resonating.

You could be right - but my quick persual of the diagrams didn't look like they left any extra room for insulation. It looked like they used all of the room down there for an air cavity forcibly refreshed by powered blowers.

Hmmmmm, how about putting down that floor for humidity control, then putting an isolating layer with insulation and neoprene over that, then the floor to walk on?

-lee-

[ola]

Some of the Swedish pages show variants with insulation but I still don't think that system looks too revolutionary. Hockey pucks, sturdy joists, mould resistant insulation and tounge in groove floor fibre board would probably yield at least as good a result but cheaper, because it isn't called a system.

[John Sayers]

Surely all you need is a layer of plastic between the concrete floor and the contruction to stop the ground moisture seeping through capillary action up to the wood floor.

cheers
john

[ola]

You should (almost) always put a moisture barrier on the concrete slab first and depending on how bad the moisture problems are, it may be enough. It's a common practice and it works in most application. You may end up with a very cold floor though so you may want to biuld an elevated floor for that reason. If you do, it's very important not to trap moisture in the elevation, because moisture will get through the barrier. So, you need a breathing floor or vents to allow some circulation below the floor. You should not need enough circulation to get large ammounts of moisture out. If you do, your moisture problem was too big to start with and you need to drain the consruction from the outside.

Heated floors are almost always worth the extra cost in cellars so you might want to look into that as well.

[j0nas]

First, I'd like to thank everybody for all their comments and suggestions.

Ok, I'm still not 100 % sure what to go for. I still think I'll need a vented floor.

Is it possible to calculate the resonance freq. (standing waves?) if I for instance have 70 mm (about 2.76 inches) space in between the basement floor and the top floor? The standing wave would then be at 35 mm, or am I wrong? The speed of sound is about 340 m/s... Don't remember how to calculate the freq out of these facts. Someone, please help?

Thanks,
Jonas

[ola]

The standing wave should have nothing to do with the resonace frequacy of the floor, which btw is near impossible to calculate.