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Insulating mechanical room ceiling in otherwise finished basement

ChrisDIY's Avatar
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08-10-04, 01:30 PM   #1  
Insulating mechanical room ceiling in otherwise finished basement

The basement in the brand-new spec house I bought last year in N. E. Illinois is divided into four rooms. With the exception of the mechanical room (containing the water heater, a furnace, structure wire panels, a rather noisy booster pump for sprinklers, and a large opening to elevated (about 5 feet), concrete-covered crawl space), every other room is insulated and finished with drywall, vents, registers, etc.

The mechanical room (about 8-9 feet below grade) and crawl space (2-3 feet below grade) are not insulated in the ceiling (one can see pipes and heating ducts between joists) and are directly below the hardwood-floored kitchen and mud room on the first floor. Primarily for sound proofing and perhaps for thermal insulation, I am thinking about adding insulation in the ceiling between the joists in these rooms. When the furnace and booster pump are on, the sound travels right through the subfloor and hardwood floor in the kitchen and mud room. It can get noisy, especially at night.

While I am somewhat handy, I have never worked with insulation and have a lot of questions.

What type of insulation should I install? What R-value and unfaced or faced with a vapor barrier? If I use faced insulation, which way should the vapor barrier face, upward toward the bottom of the kitchen floor or facing downward toward the basement floor? Since I don't want to spend the time or money to close up the ceiling, how should I make sure the insulation stays in the ceiling between the joists?

Your help will be very much appreciated. Thanks.

Last edited by ChrisDIY; 08-10-04 at 02:10 PM.
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homebild's Avatar
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08-10-04, 06:26 PM   #2  
Insulation over a mechanical Room

Adding insulation over a mechanical room in the ceiling joists will only provide marginal (if any) sound reduction.

If you do use insulation, it should be fiberglass and not have any facing on the fiberglass at all.

You'd have better results installing an acoustical ceiling tile than adding insulation and then again achieve only marginal sound reduction results.

speedy72's Avatar

Join Date: Apr 2003
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08-17-04, 09:21 AM   #3  
I'm not an insulation expert but I have some experience with sound control. How much effect the insulation has depends on how low or deep the sound is. If it's kind of mid range stuff, like your voice, insulation can do a very good job of lowering the level that reaches you. either way insualtion will kill the noise somewhat but you need to start at the sources first. Get a quiet pump for the sprinklers or put a cover directly around it. Depending on what type of furnace you have there are different solutions available. I would suggest contacting the manufacture of the equipment and finding a good contractor to help you get the equipment quiet first. Then put the insulation in.

P.S. a layer of outdoor carpet on the floor of the mechanical room had a small but noticable effect in my house. All that noise slapping off of the concrete is coming right up through your floor.

Ed Imeduc's Avatar

Join Date: Aug 2002
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08-17-04, 05:09 PM   #4  
Id also have to ask how are all the pipes you talk about held up to the floor. They should be fixed so they can float.
Then you say duct work. There is a flex like set up that you can use there on the duct work to the furnace. this way no furnace noise goes right into the duct work. Set that pump on a rubber pad. Id do all of this first and see what you have .
Id put a 6 mil poly down over that cement floor in the crawl space insulation on the wall up to the floor joist. With R19 up there just on the sill plate in the joist


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