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Guide to HVAC Duct Sound Control in Buildings InspectAPedia®  -     Principles of sound transmission in buildings How to make a building quiet: sound isolation strategies Sound insulation designs for building walls Sound control for building floors How to control plumbing noises & sounds List of soundproofing materials Tables of sound control data for buildings

Here we discuss methods and materials used to control sound transmission in buildings: how to make a quiet home, office, or place of business using sound isolation for ceilings, floors, walls, plumbing, etc. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons. Our page top photo shows a typical fiberglass lined HVAC duct interior. The gray debris stuck to the fiberglass is usually house dust, comprised chiefly of skin cells and fabric fiber. Sometimes more troublesome debris collects on interior HVAC duct insulation.

© Copyright 2009 Daniel Friedman, Steve Bliss, Wiley & Sons, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

HVAC Duct Insulation Options for Soundproofing & Noise Reduction in Buildings

As stated in Best Practices Guide to Residential Construction: Use fiberglass ductboard or fiberglass duct liners to quiet the noises of fans and moving air. Avoid sharing a common duct between two rooms that need sound privacy. Elaborating on some duct insulaton considerations: HVAC experts advise us that conventional practice is to insulate the interior of metal ductwork in order to minimize transmission of HVAC equipment sounds throughout a building. Some fiberglass duct liners are plastic coated and may be able to be cleaned using gentle procedures. But most common is the use of un-faced fiberglass duct interior insulation, typically treated with a surface resin binder to help reduce movement of fiberglass particles into the air stream. Our fiberglass lined duct insulation photo (left) shows clean new metal ductwork with a pink fiberglass mat sound and temperature insulation installed on the duct interior. Our page top photo shows that building dust and debris quickly adheres to fiberglass inteior duct insulation.

However our work on indoor environmental and air quality topics suggests that from an indoor air quality maintenance view, we perfer to see insulation on the exterior of metal ducts. That approach permits the ducts to be cleaned, and it reduces the chances of mold growth in the ductwork. See DUCT SYSTEMS and see Other Places to Look for Hidden Mold for more about places to look for duct system defects and hidden mold on HVAC systems. Mold in Fiberglass Insulation illustrates problem mold growth in fiberglass inculation including in duct systems. Construction of HVAC ducts from foil-faced insulating board (photo above left) combines sound and temperature insulation with aluminum foil to product ductwork that is quiet and cleanable using gentle methods.

Other steps to reduce HVAC system duct noise in buildings include: Proper HVAC duct mounting and routing to avoid tight contact with floor framing without use of sound isolating mounts Selection of the proper air handler blower size and speed Location of the air handler unit away from occupied space; if constructing a sound-isolated framed-in enclosure for an air handler for heating systems that burn fuel (LP gas, natural gas, oil, wood) be sure that your soundproofing does not prevent provision of safe and adquate combustion air. An outdoor combustion air supply can permit near total isolation of HVAC equipment from the rest of the building. Our photo (left) shows a furnace mounted in a mobile home closet. Owners, in an attempt to reduce furnace noise in the adjacent living space, closed off the return air inlet by installing a solid door. Heating output was substantially reduced and heating costs increased by this bad practice.

-- Adapted with permission from Best Practices Guide to Residential Construction.

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• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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INTERIORS of BUILDINGS
AGE of a BUILDING - how to determine
AIR BYPASS LEAKS
AIR LEAK DETECTION TOOLS
AIR LEAK MINIMIZATION
AIR SEALING STRATEGIES
ANIMAL ALLERGENS
ASBESTOS IDENTIFICATION IN BUILDINGS
ATTIC LEAKS, CONDENSATION & ATTIC MOLD
BATHROOM VENTILATION
BASEMENT HEAT LOSS
BASEMENT LEAKS Moisture or Mold
BLOWER DOORS & AIR INFILTRATION
CHIMNEY INSPECTION DIAGNOSIS & REPAIR
COMBUSTION AIR for TIGHT BUILDINGS
CRAWL SPACES
ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR
ENERGY SAVINGS in BUILDINGS
ENVIRONMENTAL HAZARDS
FIREPLACE Damage & Unsafe Hearths - Settlement
FLAT ROOF MOISTURE & CONDENSATION
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOORING TYPES & DEFECTS
FREEZE-PROOF A BUILDING
HEAT LOSS in BUILDINGS
HEAT LOSS DETECTION TOOLS
HEAT LOSS INDICATORS
HEAT LOSS R U & K VALUE CALCULATION
HOUSEWRAP AIR & VAPOR BARRIERS
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
INSULATION IDENTIFICATION GUIDE
INSULATION LOCATION for BASEMENTS
INSULATION LOCATION for CAPES, CRAWLSPACES
INSULATION R-Values & Properties
INSULATION & VENTILATION INSPECTION & IMPROVEMENT
INSULATION LOCATION for BASEMENTS
INSULATION LOCATION for CAPES, CRAWLSPACES
INSULATION for GREENHOUSE or SOLARIUM
INSULATION MATERIAL IDENTIFICATION GUIDE
INSULATION R-Values & Properties
Insulation Values of Log Home Walls
LOG HOME GUIDE
MOBILE HOME INSPECTIONS
MOLD INFORMATION CENTER
ODORS & SMELLS DIAGNOSIS & CURE
PAINT FALURE, DIAGNOSIS, CURE, PREVENTION
PLASTER & BEAVERBOARD & DRYWALL
ROT, FUNGUS, TERMITES
  TERMITE SHIELDS vs TERMITICIDE
ROT, TIMBER FRAME
SEARS KIT HOUSES
SOUND CONTROL in BUILDINGS
  ACOUSTICAL SEALANTS
  Principles of Sound Transmission
  How Sound Levels are Measured
  Sound Absorption vs. Sound Isolation
  Sound Isolation Strategies
  Cut Off Flanking Sound Paths
  Sound Transmission Class Ratings
  Sound Control for Walls
  Sound Control for Floors
  Sound Control for Plumbing
  Properties of Soundproofing Materials
  Acoustical Sealant for Sound Control
  Resilient Channel for Sound Reduction
  Insulation Details for Sound Reduction
  Gasketing for Noise Control
  Duct Insulation for Soundproofing
  White Noise & Sound Conditioners
STAIN DIAGNOSIS
STAIRS, RAILINGS, LANDINGS, RAMPS
STUCCO OVER FOAM INSULATION
STRUCTURAL INSPECTIONS & DEFECTS
SUMP PUMPS GUIDE
THERMAL TRACKING & HEAT LOSS
VAPOR BARRIERS & AIR SEALING at BAND JOISTS
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VAPOR BARRIERS & HOUSEWRAP
VAPOR CONDENSATION & BUILDING SHEATHING
VENTILATION in BUILDINGS
WATER ENTRY in BUILDINGS
WINTERIZE A BUILDING
WOOD Burning Heaters Fireplaces Stoves

• Marpac, produces white sound generators, a product that they identify as the Marpac sound conditioner. Marpac can be contacted at http://www.marpac.com/ or contact the Marpac Corporation, P.O. Box 560 Rocky Point, NC 28457 Phone: 800-999-6962 (USA and Canada) Fax: 910-602-1435 1-910-602-1421 (worldwide), 800-999- or email: info@marpac.com
• Sound Oasis sound conditioners are produced by Sound Oasis: http://www.sound-oasis.com/ email: info@sound-oasis.com or 1-866-625-3218

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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Wiley.com and also at Amazon.com. See our book review of this publication.

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