Help / Comments - New Construction - Sort of...

Audiofanki, they are called engineered I joists. The ones with the 2X4 on the top and bottom are the best. 18" centers, I would think more like 16" centers, hopefully not 19.2" centers. With these I joists the builder usually does not install any bridging supports between them. I would find out how much he would charge you to install solid bridging at least down the center span of the I joists. Sub floor 1/2" or 5/8"? Are you installing a hard wood flooring over this? another 3/4"? If not and it is carpet usually the subfloor is 5/8" min and even 3/4". An above post suggested a min of 1" to 1 1/4 thickness, that is a good idea but you need to get on the ball and talk to the builder. You may have a floor thickness issue of the area just on the other side of the room entry door to contend with.

As for your wall construction you may want to check out this site.

http://www.asc-soundproof.com/iso-diagrams.htm

Jim

Tom - Thanks for the email & advice!

Jim - It has been a monsoon here lately, I will most likely try to get up to the subdivision and get a better measurement on the I joists. From what I have seen so far, you are correct. There is no bracing between the I joists, and they seem to be spaced fairly wide at about 20" between the I joists. Is there a rule of thumb to follow or look up? Yeah the sub floor was either 1/2" or 5/8" - I will try to nail that down tomorrow as well. I will not be going with hardwood in that room, as the wife and I plan on turning it into a family room/children play area in 5 or 6 years, thus she wanted it carpeted. At that point I will move the system to the basement which will be a 16' x 24' room. But that may happen further down the road as well, thus I would like to make sure the floor has minimal bounce.

Do either of you feel that putting solid bridging supports down the center span will reinforce the floor enough? Or would you try to add a few more I joists and minimize the spacing between the I joists a few inches? If either of those are done and I am going with carpet, should I ask for another 1/2" layer on top of the initial 1/2" or 5/8"? Or does 1" thick exist and just request that?

As for the noise "isolation" I have a fairly accepting wife. She really isn't worried about me "containing" the sound much at all. Since the back wall (behind the speakers) of the listening room will back up to our beds headboard in our master bedroom I will be installing the "wide green insulation tape" ( found here : http://www.soundproofing.org/infopages/Tape.htm ) on the both sides of the studs on that wall. The isolation tape basically seems like a gasket material that will provide for some isolation to reduce the vibration and sound transmission from the drywall to the studs and through to the other sides drywall.

Also, do either of you feel the request for a second layer of drywall will be advantageous? I was thinking more rigidity of the walls would be helpful. If it really isn't helpful to double up the drywall, I will most likely transfer the funds allocated for the additional drywall to the flooring or joists.

FYI- I do have some time to work on this for a few weeks, as our contract just went in last week, they are working on the permits now and should be breaking ground in a few weeks... so by the time the basement is poured and the framing begins, I anticipate it to be at least 6 weeks or so away.

Thanks again for all the help.

I personally would not want the floor joists on 19.2" centers. Pay the extra for 16" center. Basically you would be adding one "I joist" for every 8' run. 16" center is a lot better solid floor. Something does not add up with the 1/2" sheeting over the floor joists. 3/4" min is usually used if covered by carpet. I bet the house you were looking at was 5/8" subfloor with 5/8" or 3/4" hardwood floor to be added over that.
Sounds like this is just going to be a temporary audio room.
I would forget the extra drywall and such. Save the money for the audio room in the basement. That will be a better room than one on the second floor. Especially if you want to crank up the volume.

Jim

Thanks again Jim. I am not fluent in builder/construction terminology, thus I am assuming if I ask the contractor to put the I joists on a 16" center, that is the amount of spacing between the I joists? The house in which I was measuring was not mine, just the same floorplan so I am unaware of what flooring they will be finishing in that room. However, as I am going with carpet you say to request a minimum of 3/4" subfloor? Even though this will most likely be a "temporary" listening room, it will still be five or six years, so I would have no problem with the double drywall of the walls - IF it will help at all sonically. We will most likely turn it into a small home theater room that doubles as a family room.

Thanks again!

Hello Kirk - I concur w/ Jim - I simply wouldn't accept any subflooring (plywood) less than 3/4", and I would further stipulate 1/4" (preferrably 3/8") underlayment before laying carpet. I will simply state - a finished floor thickness of only 5/8" inch would be a joke! And I also agree, since apparently the subfloor will not be all that beefed up, to specify 16" on centers for the I-joists. To check this, find the midpoint of the top flange of any joist (width/2) and place a mark - then do the same on the neighboring joist. Measure the distance between these two marks - that will tell you the on center (o.c.) spacing of the I-joists. Jim was also correct to recommend solid blocking between the joists. I did a quick read about wood I-joists on the net, and from what I gathered, they will still exhibit flexing, but this can be reduced with blocking. A lot of this depends on your builder - is he a hands on carpenter, leading the crew, or does he drive around to his sites all day, in a new pickup and carrying a briefcase. IMHO, the latter variety will cut every corner imaginable to add to his bottom line. 'Nuf said.
And to reiterate one last time, insist on construction glue being applied on top of the joist before the plywood is layed. Unless you are present during this phase, there is no way of knowing if this was indeed done, other than to find the empty "tubes" laying in the trash pile later. You need to tell the builder you expect to see these. Quite simply, there is either the right way or wrong way to frame a house. Again, best of luck ... Tom