So the Mrs. and I were out on the weekend looking at some pretty nice new detached townhomes that had completely inground basements, with the exception of window wells. Pretty high ceilings down there, easily 9' maybe as high as 10'.

I've searched the archives here, and the web, but I can't find any discussions on the pros and cons relating to sound in below grade rooms.

Clearly there's limited sound transmission to the neighbours (a big plus in and of itself, I'm thinking), but is there anything else that should be considered? Apart from the obvious dimensions stuff. Rectangular rooms here; maybe 16 x 24 or so in one possibility, 19 x 14 in another.

Or is it just another room that would benefit from the regularly suggested treatments?

(Will not say anything about dimensions, except to stay away from common multiples... 16x24 bad... 14x19 good).

My theater is below grade, with poured concrete walls behind the drywall. When I first set up the room, there was extreme echo in the room, much more than an empty room above grade. I treated the room with sound absorption panels and it made a huge difference.

If the room is not finished, they sell kits to properly sound insulate a room. I don't have a link handy, but it involves insulating the walls with a higher density material, and I think the drywall even gets isolated using special attachment hardware. Can't say whether or not they work because I haven't tried it.

There are pluses to below grade (transmission to neighbors is one as you stated). Since the speaker sit on the concrete slab, there is less transmission to the rest of the house. Also, one of my subs is in the concrete corner and it is definitely more reinforced than the one that sits in the drywall only corner.

With proper sound treatment, I don't think there will be much of a problem. I love the sound my system puts out.

Seems like it would be MUCH easier to isolate from the rest of the house since you're only dealing with the access and one plane instead of six.

Thanks for the input. Much appreciated.

This just became very interesting indeed. Will need chat further at home tonight and then investigate this seriously.

Most houses down here in the US have full basements, it is not unusual. I guess I thought Canada was the same? Florida and other southern states are different as the water table is so high and the soil is different.

In regards to sound transmission, I'm sure the folks in our development can still hear the loww bass from my 3 Axiom subs when I crank things up, but not as much as my wife and kids upstairs.

Depends on the ice thickness and temperatures.
Some of us just cannot dig that much into the ol' igloo basement until you hit permafrost.

I recently built my theater in a walkout basement, but 3/4 of my theater room is thick concrete slab walls. I built the stud walls out about 6" from the walls and filled the cavity with insulation. I chose a thicker shag style carpeting and used the thickest carpet padding available. The sound is amazing and the concrete walls behind the drywall and studs does isolate most of the sound to inside the room, which is great for the neighbors and my wife! Bottom line is I wouldn't worry about the concrete walls...you should have no problem building the theater of your dreams!

Take a look at my first pics in the Axiom gallery (Skubics Home Theater). They were just uploaded this morning so it very well may be the first picture you see in the "Wall'O'Fame" box to your left.

A benefit mentioned already that I like is that since there are concrete walls already (at least on any walls that are at the exterior of the house) it is pretty easy to "float your wall" since you need to build walls anyway to hang drywall and such, you can just put them an inch away from the concrete wall and do other accoustic treatments to isolate the room from the rest of the house. That is also where it is easier to build a front stage (filled with sand) to create a barrier between front speakers/subs and the concrete floor without wondering if all of that sand will weigh too much....

Randy's sitting on what - an acre? - of lot and he thinks he lives in a "Development". Cute. Iowa.

You guys with dedicated basement theatres make me jealous sick!

Not to mention the "problem" of dealing with three Axiom subs...

One day I hope to share your woes. Seriously.

I get "the look" when my measly Panny receiver approaches -40. I don't think that it's ever seen anything near -20.

Only con I can think of is worrying about water seepage. If you don't have that worry, then you should be fine. I have 2 electric sump pumps and a 24V battery backup sump pump to combat the worries.

I'll bring the topic of pumps up with the developer if we get that far. Didn't think about that originally. My current house doesn't go below ground level.

Thanks!

I've got a 19' x 28' room in the basement of my house and there are no problems. I insulated (r-13) around the perimeter and ceiling to "deaden" the audio a bit, but nothing special beyond that. (Since you are in Canada, you might consider using flannel instead ).

A sub is the only thing that should provide any challenge. It is INCREDIBLY difficult to contain robust LFE. My HSU VTF-3 HO just pummels the china cabinet upstairs in the dining room, even with the insulation.

As an aside, pretty much all of my friends have their HT in the basement.

Good luck with it - you will enjoy the end result.

I had a problem with water seepage, but I went to see my doctor and they have a pill for that now.