Who's the best person to insulate a steel building?

[Bobby Robbinett]

For sound isolation you need Roxul Safe-N-Sound insulation and double layers of drywall with Green Gue in between and using drywall isolation clips. That is the easiest way. A better and far more effective way would involve adding another stud wall with another double layer of drywall with Green Gue and drywall isolation clips but have this stud wall/drywall wall with a 4” air gap between it and the outside wall.

[Jim Becker]

Bobby, the OP would have to decide if building "walls within walls" at whatever cost it entails is necessary to meet his goal of reducing sound transmission to the outside of the building or if application of spray foam will meet the goal in one step. The method you describe is one very valid way of sound insulating rooms for sure!

[Frank Pratt]

I read those independent claims. The Open cell had an STC of 37 and the closed cell foam was 36. Fiberglass batt and wool was closer to 45-50 STC. What I don't understand is why they claim that it doesn't do much as a sound barrier. unless i'm reading it wrong. I'm not sure if 37 means a 37 decibel reduction or 37 percent, but that's a big amount imo.

STC is a scale that indicates how much sound is blocked by the wall assembly. Lower lets more sound through, higher is less sound. I haven't seen any studies that had closed cell & open cell that close in STC. Open cell is quite a bit better than closed. There must have been other variables between the 2 samples, like insulation thickness.

Closed cell is certainly better at stiffening a structure.

[Travis Conner]

From what I understand is if a machine creates 100 decibels just as an example, then if it as an stc of 36 then it will be 64 decibels on the other side of the wall.

[Jim Becker]

From what I understand is if a machine creates 100 decibels just as an example, then if it as an stc of 36 then it will be 64 decibels on the other side of the wall.

Which is really low sound level because of how the decibel scale works...

[Daniel O'Neill]

Which is really low sound level because of how the decibel scale works...

Yeah 36 is like a whisper. We have a rural road about 500 ft away and the semis that drive on it register about 45-65 depending on the day & wind. As I understand it the sound drops significantly with distance too. So if you're at 36 outside the wall and the closest neighbor is 100 ft away they might not hear much at all.

[Travis Conner]

I'm going to go with rock wool batt insulation. STC of 50 which is as good as it gets and it's cheaper than the closed cell foam. I just need to find someone who will install it on a building that's always been built. They typically like to put it on over the purlins then put the roof on with metal buildings. Nobody answers the phone though and i've called 5 places. That first guy I talked to on the phone acted like spray foam was the only option I had, now I've researched it and it sounds like that spray foam tends to rust out the building. The spray foam doesn't look good anyways imo, unless they can smooth it out real good.

[Jim Becker]

There should be no resulting rust from closed cell spray foam if it's applied correctly...just as there's no issue with it being applied directly to roof sheathing relative to condensation, assuming the local code folks don't force don't force baffles for ventilation which in turn can cause condensation issues if there's an issue with air flow. (DAMHOKT!)

Have you confirmed that the rock wool batts are available in the size/format you want need for your application?

[Frank Pratt]

The spray foam doesn't look good anyways imo, unless they can smooth it out real good.

Rock wool isn't pretty either. But you wouldn't leave rock wool or foam uncovered anyway.

[Bill Dufour]

Rock wool does not burn so it can be left exposed to collect grease and dust from the air.
Bill D

[Bob Cooper]

One thing to consider with closed cell is it won’t allow water to pass through unlike open cell. Roofers I talked to didn’t like it because if you did have a roof leak it could be tougher to know the leak existed.

[Bobby Robbinett]

I would imagine that if your building doesn’t have 2x4 walls or similar on the ceiling then it would be difficult to install rock wool. I wasn’t sure if your shop is a pole barn or red iron metal building. You would spend a boat load of money framing up walls and installing a drop ceiling if you don’t otherwise already have one. This would be a moot point if you went with spray foam. There are so many advantages to using spray foam. I can get closed cell spray foam done for $1.48 per square foot in my area and no tax if you pay cash. LoL. It would also seal up your ceiling/roof and stop or prevent any leaks. It does wonderful on keeping the cool air in your shop in the summer. Makes your shop into a Yettie cooler!

[Travis Conner]

It's got the red iron framing. I've never seen a steel building with a drop ceiling.

[Jim Becker]

It's got the red iron framing. I've never seen a steel building with a drop ceiling.

Rockwool, fiberglass, etc., all need to be supported by structure. The is a big reason that spray foam has become more and more popular with the kind of building you have (along with other sprayed materials that stick directly to the building)...they don't require the cost of constructing framing including ceilings. Spray foam is "cheap" compared to adding walls inside of walls if you didn't intend to to that anyway.

[Jack Llewyllson]

Anyone know anything about soundproofing a shop? Like I said in my earlier post, I want to be able to work in the shop late at night and prefer it if the neighbors don't here an ounce of noise. Is there a sound barrier that can be placed in addition to the closed cell foam? From my research the spray foam doesn't really block the sound like other insulation methods do. I called a few other contractors, but nobody answered the phone.

"And now, for something COMPLETELY different"...

Acoustical facilities, such as Benaroya Hall locally, favor the use of rock wool (mineral wool) insulation with a fabric cover rather than paneling or sheet rock over the inside face. It is considered state of the art now, AFAIK.

Conveniently, it's also pretty dang good insulation. Also, unlike fiberglass or open cell foam, rock wool is hydrophobic, so it won't retain moisture or precipitate mold growth.

I also don't want to burden the neighbors, which is one of the reasons I'm going to install it in my stick-built shop. For obvious reasons, I won't be covering it with acoustical fabric, though.