Room Problem Improvement Question: Over a Garage


My current listening space is a second story room located over a 3 car garage and about 18-20'x30' that is a 2x4 stick construction supported by 2 microlam beams that run over the garage, parallel to the cars parked below, supporting the joists and 3/4inch subfloor beneath it. The surface is thin pile carpet with a thin pad under that.

The previous owners finished the space themselves and as such did not insulate at all between the floor joists to the uninsulated concrete garage underneath. The Garage ceiling below is about 10 ft and has blueboard with plaster over it.

Acoustically speaking, this is not a bad space, with ceilings being around 8' and is actually one of the better listening spaces I've had in my last 3 houses, even though on the left wall is a 45degree slant coming out around 3 feet running a good part of the length of the long wall next to my left speaker. I get great depth and fairly decent imaging and tonal balance, but I have floors which leak a considerable amount of bass and are INCREDIBLY SPRINGY! I can be walking softly on the other side of the room and my lead and sand filled Billy Bags rack cannot stop my needle from bouncing on a record! Also, I'm concerned about room nodes and overwhelming the space with all the sympathetic vibrations/resonances going on all at once, and even some of the reverberation from sound leaking down, bouncing off concrete then coming back up.

I am getting some very full range very dynamic and very heavy loudspeakers delivered in August and am concerned about this enough to begin getting quotes from builders for some kind of fix before their arrival.

Some of the ideas I've been given include:

-Spraying Icynene foam between the floor joists from the garage below to fill the spaces that are uninsulated

-Placing another layer of subflooring with a product called Advantech, which is a type of OSB that is far heavier than 3/4" subfloor then resurfacing with either:

a) Hardwood or
b) Another carpet or the same one if it can be salvaged.

- Just placing hardwood over the 3/4 inch subfloor and call it a day.

- Move the party to the 3car garage below which would entail getting HVAC systems,carpeting as well as walling off my garage doors and dealing with my wife having to park outside during the cold snowy winters and rain.

Any ideas on what to do in this type of a space? Has anyone had a similar problem with a room over the garage? The span is so long (23 ft) that I think it may be a lost cause and that adding subflooring ($2k) plus carpeting ($3k) may not even do the trick since it may be the floor joists below that are causing the problems.

My question is if anyone out there has done this type of project, what were the results and should I give it a try or just wait and see what happens when the new speakers arrive in August? It may be impossible to move them once they are in place. I'm also concerned that if I use wood flooring the room may become too bright sounding by not having the wall to wall carpeting currently in the space.
owl

Showing 4 responses by hbarrel

It might be a positive thing. The question how posiitve. Personally I don't think any gains would be worth the additional expense.
Spend that money on running a dedicated line or two.
Question?
The orginal post states 2x4 stick construction.
The floor joists (garage rafters) are 2x4's as well? Not 2x6's?
If the floor joists really are 2x4's they are then most likely on 18 or 24 inch centers.
If so... splurge and hire a structural engineer (or competent "truly" professional carpenter) to come in and assess the situation.
Is the center ridge in the garage still straight?
If the previous owners totally ignored sound construction practices in their effort to save some $$$ in this DIY room there might be bigger issues than what you know.
If you have 2x10's (16" centers) that are allowing the floor to bounce I'm going to guess there is no "X" bracing between the joists.
The sub floor must have a minimum of nails and no PL400.

Personally, I think the cheapest fix would be to tear the garage ceiling out and fix things correctly. Insulate, cross brace, run any required wiring and HVAC...
Drywall is relatively inexpensive and besides it is the garage. Plus if additional support columns (or sisters) are required they can then be properly installed.
Don't concern yourself with the metal cross braces and them creating any electronic issues. That's a non-issue.

Wow. I'm surprised at the need to go in from both sides to install cross bracing. I'd really question that requirement.
Although in the end it might make the job easy to perform and allow the guy to get in and out in an orderly fashion.
i.e. cheaper in the end

I have a funny feeling he feels that the bottomline fix is sistering the microlam to the existing joists.
Based strictly from what you've written I'll agree. However do question him as to the need to sister every joist or if every other one will do or every third, etc.

Make sure that when the 3/4" sub-floor goes back down it truly ties together the span. Staggered joints, screwed and glued.
He's really have to do some serious selling to get me to agree to another sub-floor on top of the one that just got glued and screwed. Especially if it's 3/4" underlayment.

Remember the five P's; Proper planning prevents poor perfomance.
Or the seven P's; Proper prior planning prevents piss poor perfomance. :)

Just buy some commercial grade low nap office carpeting ($15 a yd with pad/installed) and enjoy your new room.