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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
newbee
4,825 posts
 
Dumb question time. When you did you RTA measurements were you also searching out the nodes and nulls. Could it be as simple as finding the best nodes for speakers and listening positions? Regarding equipment vibration casued by floor movement, can you beef up the floor under the equipment by using piers under the floor extending down to the garage floor, even if set at an angle. If thats possible, then you can put down a layer of vibration absorbant materiel between your floor surface and the base of your equipment to minimize vibrations. BTW re footfalls and bouncing stylus, do you by any chance have a suspended table? If so, consider that contrary to common perception suspended tables don't like foot falls. A good isolation platform and an unsuspended table can be much better.

What a bummer, having a great space for a dedicated room, great equipment, and a lousy floor. :-(
zargon's avatar
zargon
453 posts
 
Owl, I have a similar room over a 2 car garage. The floor was somewhat spongy and was driven into a strong resonance at 31 hz. This was solved by building a beam out of 2x6s in the shape of a "T" and lag bolting the top of the "T" to each joist across the center of the garage ceiling. The "T" beam can be broken into pieces if necessary to avoid any obsticals. This beam resists flexing and ties the joists into a much tighter network. This improved the situation greatly, and might be enough for you.

However, as a extra measure, I then added a steel post in the center by jacking up the beam slightly and sliding it between the beam and the concrete floor. The post was centered between the two car parking slots.

Did it work? The 31 hz resonance is much reduced (some is still in the walls) and you can now go into the listening room and jump up and down as hard as you wish and the turntable (unsuspended on a mass loaded stand) is unaffected.

This solution is very inexpensive and totally unabtrusive to the listening room. You do have to tolerate the beam, but if you place it just ahead of the car doors (near the rear view mirror), it really doesn't get in the way. My total cost was well under $100.
rex
245 posts
 
Do what Zargon says - it works. You can even paint the steel jackpost bright orange so it's more noticeable when parking in the garage.

The nice thing about Zargon's suggestion is that the fix works, but is not permanent. Permanent structural modifications to a house are risky (especially if you DIY outside of code). Not necessarily risky to life/limb, but risky in the sense that you may end up with a non-saleable house.

Along those lines, don't modify your garage into a listening room. It's tempting, but it can have severe negative effects on resale value. Most people who buy a house with a garage want to use the garage as a garage. If it's been turned into living space, it's no longer a garage. Also, if you live in an area with property taxation, your remodeling project will force a reassessment (upwards) of your home's tax value.
ausjoe
98 posts
 
Zargon gave you good advice. I do wonder about an uninsulated garage joined to your living area. I think your idea of Icynene might be worth doing dependent on the price as you get the side benefit of enegy savings and better resale value. IMHO
hbarrel's avatar
hbarrel
536 posts
 
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.
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