I am moving my studio into a (mostly) unfinished basement space, and am opting to do the "rigid fiberglass with Guilford fabric covering" thing on the ceiling that Ethan recommends on his website, opposite a laminate floor. It's a 90 year-old house, big wood support posts and beams in the basement, the joists are 7.5" deep & spaced 16" on center, height to actual ceiling (floorboards) is 7.5'. The control room is a cozy 10' x12.5', and there is a stairway dividing the control room and studio areas so the joists in each side are only 10' long and not contiguous (here is a picture):




Here's what I need help on:

1) Is there an extra benefit to using 705 (paper facing up) instead of 703 in the ceiling? How thick should I go?

2)The joists seem a bit resonant when I tap on them (maybe because of their shorter length)....will having the fiberglass in the cavity dampen them a bit, even though the rigid won't be in close contact with the joists like the fluffy stuff would be? Do I need to be concerned about them acoustically?

3) To increase the isolation from above a bit more (there's fir hardwood and an area rug above the control room side and fir/foam sheeting/laminate over the studio side), I was thinking of either: a.) Green Gluing and screwing 5/8" drywall strips to the ceiling in between the joists (plus acoustic caulk maybe at the seams?); or, b.) strips of vinyl sound barrier (1 lb/sq ft) stapled and glued. Any thoughts on either, or suggestions for alternatives? That seems to be the downside of the fiberglass & cloth ceiling vs. the usual drywall ceiling... low STL.

4) Any need to dampen the 5" square horizontal support beam on the stairway-side (maybe mass loaded vinyl?) so sound in the studio doesn't vibrate it mechanically (directly and from the floor via 2 support posts) and then flank to the control room joists and the floorboards in contact with both joists and beam?

I'm puzzling over this, since I don't want the 5/8" drywall/steel stud with Roxul/double 5/8" drywall wall I'm putting between the control room and studio area to be significantly comprimised by ceiling flanking. I am going to extend the drywall all the way up vertically to the actual floorboards (cutting notches for the joists and caulking the edges) so it should be airtight and the actual beam will be behind the double layer of drywall. It's the mechanical transfer I'm worried about.

Thanks in advance for any input you guys can give...it's a bit over my head (yikes...sorry...couldn't resist...)

Michael

Hi Michael,

Welcome to the forum.

> Is there an extra benefit to using 705 (paper facing up) instead of 703 in the ceiling? <

Probably not. The absorption on the ceiling is mostly for higher frequencies, so the extra cost of 705 is less justified. And 705 is actually a little less absorbent at high frequencies.

> How thick should I go? <

Two inches will do the job, but four inches is even better because it extends the absorption to lower frequencies. Indeed, four inches of 703 is better than two inches of 705 and it costs the same.

> will having the fiberglass in the cavity dampen them a bit <

I don't know. Maybe. Then again, I'd think the resonances would be at a pretty low frequency, no?

> I was thinking of either: a.) Green Gluing and screwing 5/8" drywall strips ... <

I don't have any direct experience with that either, so I'll let others comment.

> Any need to dampen the 5" square horizontal support beam <

Probably not. Your main problems are reflections from large surfaces.

--Ethan

Thanks for the feedback, Ethan.

If I can pick your brain a little more....I'm planning on building 4 floor to ceiling corner traps, 4" thick with the rear corner traps using FRK facing out to keep the room from becoming too dead. Would that be a good balance with 4" of 703 in the ceiling?

I came across the article you'd cowritten with Wes Lachot where you talk about placing a reflective border around the room perimeter--was the concern about over-absorption because the room described was being used for tracking as well as mixing?

Thanks again,
Michael

Don't use a laminate floor. They do not sound like wood. They do not hold up under studio-style traffic.

Bill

Michael,

> I'm planning on building 4 floor to ceiling corner traps, 4" thick with the rear corner traps using FRK facing out to keep the room from becoming too dead. Would that be a good balance with 4" of 703 in the ceiling? <

Sure.

> was the concern about over-absorption because the room described was being used for tracking as well as mixing? <

No, this is a concern in either case.

--Ethan

Thanks for passing that on, Bill. You're the first person I've seen say that...most everybody else on all the acoustics forums say that concrete, laminate, vinyl, wood--doesn't matter. We've got a laminate floor in the kitchen that's done pretty well against our hyper Siberian Husky's toenails ...do you mean that the laminate will sound less pleasant than a real wood floor?

Mike,

Do plastic guitars sound like wooden guitars? Do plastic speaker cabs sound like wooden speaker cabs?

What you put on the floor may not matter to some. But those who want to hear a wood tone, want a wood floor. Amp casters, drum hardware, and other things that are not typically part of the normal household play havoc with the laminate surfaces... I have seen this first hand in certain buildings where they stuck laminates in high/hard/heavy weight traffic areas. Even the floor of the elevator in my apartment building, which is a laminate, is looking ugly after only a couple of years.

Besides, it just looks phoney.

Bill