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 Suspended Ceilings: install, diagnose, repair, insulate, R-Values
- Suspended panel ceilings: choices, installation, common defects, repairs
- Catalog of common interior drop ceiling defects, how they are recognized, effects on building heating and cooling systems
- Building heat loss effects and suspended ceilings: R-values of selected suspended ceiling products & designs
- Building energy audits and suspended ceilings (drop ceilings)
- Questions & Answers about suspended panel ceilings or "drop ceilings" in buildings
- References
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
This article discusses interior suspended ceiling or drop ceiling materials, choices, installation, troubleshooting, and the effects on building heating and cooling costs when a drop ceiling is installed. We describe hazards and problems in suspended ceilings and we include a table of R-values of various suspended ceiling products and designs.
See CEILING FINISHES INTERIOR and Also see Best Interior Finish Practices and see Q&A on Building Interiors: Leaks, Stains, Damage, Repairs. Our page top drop ceiling photograph shows the typical grid system used for supporting a suspended panel ceiling.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Suspended Ceilings and Suspended Ceiling Tiles - Properties, Photos
What is a "suspended ceiling" or "drop ceiling"? According to Armstrong Corporation, a manufacturer of suspended ceiling products, [edited and paraphrased]
Suspended ceilings or drop ceilings are a ceiling suspension system that uses
a system of metal members, designed to support a suspended ceiling, typically an acoustical ceiling. A suspended ceiling may also may be designed to accommodate lighting fixtures or air diffusers.
In simple terms, a grid of metal bars, typically shaped in an inverted Tee form is hung from the building original ceiling or ceiling framing. The supporting grid is usually spaced two-feet on center to form square openings, or to form two-foot x four-foot rectangular openings into which are "dropped" prefabricated ceiling panels that are offered in a very wide range of designs and materials. [1] Other suspended ceiling system designs include a "plank look" offered by Armstrong (and perhaps other manufacturers) that is produced in 6" x 48" strips.
Typical suspended ceiling panel thicknesses are 1/2-inch to 2 1/2" except where special products are selected to add greater insulation values. Sound absorption ratings vary by individual product but it is common for an acoustic suspended ceiling panel to claim to absorb up to 50% of noise signals impacting its surface.
The distance between the upper surface of the suspended ceiling grid and the surface of the original ceiling can vary very widely, but in order to install the ceiling panels, manufacturers specify a minimum distance, typically 2" plus the thickness of the panels themselves, or a minimum distance of 2 1/2".[1]
 Suspended ceilings or suspended ceiling tiles became popular in North America in the 1960s, and can be made of fiber board or fiberglass, for example. Some have a plastic coating.
Combustible plastics, such as polystyrene, should not be used as ceiling tiles.
Suspended ceiling systems utilize a metal T-bar grid supported by wires from above. You can spot the supporting ceiling grid system in our photo (left) as the bottom edges of the grid are visible between individual suspended ceiling panels.
Advantages of suspended ceiling systems include relatively good acoustic properties, ease of removal to access things above the ceiling, and individual tiles can be replaced readily. On the downside, suspended tiles lower the ceiling at least two to three inches.
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Suspended Ceiling / Drop Ceiling Materials, Choices
- Acoustic panels, constructed using wood fibers, fiberglass, possibly other materials.
- Fiberglass & plastic or vinyl coated embossed panel ceiling panels, typically constructed using high density fiberglass panels in thicknesses from 1/2" to 6" (and of varying R-values)
- Metal, or embossed metal ceiling panels, in popular designs resembling antique embossed metal ceiling coverings.
- Plaster panel drop ceilings use suspended panels typically constructed of metal lath. See CEILINGS, PLASTER, LOOSE HAZARDS for a collapse hazard.
- Wood fiber or particleboard ceiling panels
Embossed Metal Drop Ceiling Panels
 Metal ceilings were typically tin and most often were installed in kitchens, during the late 1800s and early 1900s.
There are also some metal ceiling lookalike products that are actually drop-in panels, typically 2' x 2' or 2' or larger, that are actually a suspended ceiling system. It's easy to spot a metal panel suspended ceiling by looking more closely for its supporting grid.
The metal ceiling in our photo (left) is an antique metal ceiling installed in a New York City restaurant. You can see in the left of the photo that a wooden beam was also wrapped in decorative embossed metal.
This link to a different metal ceiling photo shows a typical example of metal ceiling components that are rusting through from leaks above.
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Insulation R-Values of Suspended Ceilings & Effect on Building Heating & Cooling Costs
 While it is generally true that installing a lowered drop ceiling or suspended ceiling might reduce heating and cooling costs in buildings, the actual effects, both gains and losses in building heating and cooling costs, are variable and depend on several factors. To understand the net impact of a drop ceiling on building energy costs you will need to evaluate:
- The distance between the suspended ceiling and the original ceiling or roof underside above and air movement within that area.
- The R-values of the roof, walls above the ceiling, and of the ceiling itself - some drop-ceiling tiles can be quite thick fiberglass pads that offer varying R-values;
- How the space above the ceiling is used - for example in offices or other buildings the space above the suspended ceiling is often used as a return air plenum, and the presence of certain HVAC equipment in the ceiling cavity that may increase air movement or that may add or remove heat from that space
- Air communication laterally between the ceiling cavity and other building areas - see the blue arrow in our suspended ceiling cavity photograph at above left. The building occupants and management were unaware that the conditioned space above this suite of offices was subverted by a large opening that connected the building ceiling cavity to an exterior hallway and stairwell.
- Presence of additional HVAC equipment or air movement devices that may be installed in the suspended ceiling cavity (red arrow in our photo, above left).
- The care of installation of the suspending grid and whether or not it's leaky,
- The presence of air leaks in and out of the cavity above the drop ceiling from other sources (removed panels, misfit panels, damaged panels)
- Missing suspended ceiling panels
Table of R-Values or R-Factors for Typical Suspended Ceilings & Ceiling Panels©
Our OPINION is that the overall R-factor for a suspended ceiling should not be assumed to be simply that of the panels that comprise the ceiling material. The additional factors above will need to be considered. For example, even a single significant air leak can overwhelm the otherwise stated "R-value" for a suspended ceiling.
| Suspended Ceiling Panel Material |
Suspended Ceiling Panel Thickness |
Estimated R-Value per inch [7] |
| Drywall |
1/2-inch: R 0.2 | 0.45 |
| Fiberboard insulating board |
1/2-inch: R 0.5 |
1.14 |
| Fiberglass, batts, height density |
1/2-inch: R 2.0 |
3.6 - 5 |
| Fiberglass panel, rigid (fiberglass "boards") |
1.2-inch: R 1.125 |
2.5 |
Polystyrene Expanded (EPS) insulation, low-density |
|
3.6 - 4.7 |
| Ceilume panels |
0.79 - 0.91 |
Engineering judgment (not test data). Ceilume points out that we should be interested in heat flow resistance in both directions (up out of the conditioned space and down into the conditioned space) to accommodate both heating and cooling requirements [10] |
| Ceilite™ foil-faced glass wool insulating panels |
R 2.6 - 5.9 |
Varies by season and by air space above the suspended ceiling. Combines polystyrene, reflective foil film, and an air space assumed still air [5] |
| Polystyrene board, extruded expanded high-density (XPS) |
"up to 4.5" [6] |
4.2 - 5.4 |
| Armstrong mineral fiber ceiling panels ["inert mineral components'] |
|
[8] no R-values claimed in consumer information. |
| USG Ceiling panels |
"up to 1.5" |
[9] |
| Owens Corning add-on Sonobatt suspended ceiling insulation |
3 1/2" panel, R-11
6 1/4" panel, R-19
9 1/2" panel, R-30
12" panel, R-39 |
These are add-on insulating batts and do not include the actual suspended ceiling panel itself.
Quoting: "Sonobatts Insulation are easily installed in
suspended ceiling systems by simply
laying them on top of the ceiling panel and
suspension system. Sonobatts should fit
tightly together to reduce the amount of
heat loss." [11] |
Notes to the Ceiling Panel R-Value Table:
[5] Ceilite, 4/22 Eastern Service Rd,
Stapylton 4207 QLD, Australia, Email: sales@ceilite.com.au, Tel: 1300 663 755
[6] Silent Source Acoustical Ceilings, 58 Nonotuck Street Northampton, MA 01062 (413) 584-7944 Fax: (413) 584-2377 Email: info@silentsource.com, web search 10/21/2011, original source: silentsource.com/ceilings-ac-suspend-a-
ceil.htmlhttp://www.silentsource.com/ceilings-ac-suspend-a-ceil.html
[7] See table of INSULATION R-Values & Properties
[8] Armstrong corporation, website search 10/21/2011, see page bottom footnote [1]. The phrase "inert mineral components" may refer to fiberglass. Here is Armstrong's comment about the insulation value "between floors" of their suspended ceilings:
Most ceilings are installed between floors that are maintained
at the same temperature — making insulation unnecessary.
Basement recreation rooms are at least partly heated by heat
flow through the ceiling from the heated space above. In that
case, attempting to insulate the basement ceiling surface
could actually reduce heat flow. [2]
[9] U.S. Gypsum, web search 10/22/2011, original source: colorado-ceilings.com/usg-ceiling-tile.html
[10] Ceilume,
9270 Graton Road
Graton, CA 95444, Tel: 800-557-0654 , web search 10/21/2011, original source: ceilume.com/ceiling-tile-insulation.cfm
[11] Owens Coring World HQ, One Owens Corning Parkway, Toledo OH, USA, 43659, Tel: 1 - 800 - GET - PINK, Website:
owenscorning.com |
Effects on Suspended Ceiling R-Value or R-Factors due to Space Above the Suspended Ceiling Materials
Installing a suspended ceiling can serve to reduce heating or even cooling costs in some buildings by:
- reducing the volume of conditioned space by lowering the ceiling
- providing an insulated surface below the original ceiling (provided insulating suspended panels are installed)
- providing a cavity for the addition of HVAC ducts and registers using the space between the original ceiling and the new suspended ceiling (typical application in offices and other commercial buildings)
But the effectiveness of the suspended ceiling on building energy costs for heating and cooling will be determined by additional factors that we listed earlier in this article. Here we comment on the effects on heating and cooling energy costs of
- Changes in effective ceiling height
- R-values for the original ceiling and upper walls within the space above the suspended ceiling
[Modeling & data collection are in process, CONTACT us to contribute information.]
Hidden & Visible Hazards in, on, and above Suspended Ceilings
Suspended Ceiling Tiles or Sections - some old contain asbestos?
Often you will find that acoustic ceiling tiles (shown at left - these are not a suspended ceiling product) have been installed on furring strips nailed over an older ceiling that was in poor condition, such as we show in this additional photo where demolition was in process.
However you may come across pre-1986 (date approximate) 2' x 2' or 2' x 4' suspended ceiling panels that might contain asbestos, particularly if acoustic panels were used.
See details about asbestos in ceiling products found at ASBESTOS CEILING TILES, Asbestos-Containing. |
Hidden Hazards in & Above Drop Ceiling or Suspended Ceilings
As we also discuss at WALL FINISHES INTERIOR, water damage is one of the most common problems on interior finishes.
Common water sources that show up as ceiling leaks or leak stains include roof leaks, flashing leaks, ice damming, window and skylight leaks, plumbing leaks, leaks from hot water heating systems, and condensation.
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The photo [at left] illustrates drop ceiling panels below areas of leaks.
When looking into any damaged suspended ceiling installation and especially where you see ceiling leak stains in a drop ceiling, you want to inspect carefully to determine the following:
- clues indicating that the ceiling structure may be unsafe, in danger of collapse or unhealthy, due to mold or other contaminants. Check for the presence of other, perhaps older materials above the suspended ceiling that may themselves present a building hazard or require additional inspection, testing, or cleanup. For example we may find falling asbestos pipe insulation or collapsing asbestos-containing ceiling tiles above the suspended ceiling structure. We also may find rodents such as mice or bats in these spaces.
See CEILINGS, PLASTER, LOOSE HAZARDS for an example of a dangerous drop ceiling collapse
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The photo at below left illustrates the discovery of asbestos-containing ceiling tiles above a suspended ceiling along with cases of falling tiles and perhaps amateur asbestos material removal. |
The photo at below left shows that we found bats infesting the area above the drop ceiling of a public library in upstate New York. At below right we illustrate finding mice in a similar ceiling space.
The photo [at left] illustrates both leak stains into the suspended ceiling and a missing panel, subverting the airflow design of the building HVAC system.
Continuing our examples of hidden hazards above and in drop ceilings:
- the source of the water,
- whether the problem is still active,
- whether there is any concealed damage
- the cost to correct the water problem if needed, e) and the cost to repair the damaged building materials.
- The cost to replace water-damaged ceiling panels
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Mold Contamination or Growth Found on Drop Ceiling Panels & Surfaces
Our moldy suspended ceiling tile photo (left) shows a case in which most of the ceiling tiles had become so wet that they had already fallen to the floor. One moldy ceiling panel remained in this photo - at the bottom of the image. Our lab tests found extensive Aspergillus sp., some Stachybotrys chartarum, and Rhodotorula and other yeast contamination on these ceiling materials. [Some suspended ceiling products are rated by their producers as "mold resistant"]
At above right the suspended ceiling in this bathroom had become mold contaminated due to the combination of high moisture and inadequate ventilation, not due to leaks from above.
At below left we show two sides of moldy drop-in ceiling panels found in a basement over an area of burst pipe flooding that went unattended for weeks. In this event the water and moisture originated below the drop ceiling rather than from above - a hot water spill on the basement floor (photo below left). But on removing moldy ceiling materials we also found evidence of older leaks (below right).
Advice for mold contaminated ceiling tiles
Where there is a large (more than 30 sq.ft.) reservoir of contiguous indoor mold, such as is shown on our moldy ceiling photo below, there are almost certainly health hazards for building occupants.
But as we discuss at Q&A on Building Interiors: Leaks, Stains, Damage, Repairs, small moldy areas may be of no significant health concern and can be cleaned or removed by most homeowners or a handyman who follow simple basic precautions.
We emphasize in all of our notes on indoor mold inspection and testing that a competent inspection for mold contamination begins outside, and should include the entire structure.
Even drop ceiling tiles that look "clean" might be a hidden mold reservoir if they have been wet. We discuss hard-to-see mold reservoirs in fiberglass insulation products at INSULATION MOLD.
At USING LIGHT TO FIND MOLD we provide a detailed example and procedures for using lighting to find mold on surfaces where mold may be present but where it is not immediately obvious.
Frequently Asked Questions (FAQs about suspended ceilings or drop ceiling installations
Question: Effects of drop ceilings on building energy usage, heat loss, heat gain, air movement, HVAC operation & costs
Do you have any articles on your Web site dealing with drop ceilings while doing an energy audit?
-
Christopher M. Petersen,
West Philadelphia Home Solutions
Reply: Energy & IAQ Impacts & Some Inspection Points for Suspended Ceilings or "Drop Ceilings"
 I'm guessing you're asking about the impact of suspended ceilings on building energy costs, heating gains and losses. The topic of how a drop ceiling affects building energy costs and indoor air quality becomes interestingly complicated depending on at least these factors:
- how the space above the ceiling is used - for example in offices or other buildings the space above the suspended ceiling is often used as a return air plenum,
- on the distance between the ceiling upper surface and the building roof,
- on the R-values of the roof, walls above the ceiling, and of the ceiling itself - some drop-ceiling tiles can be quite thick fiberglass pads that offer varying R-values;
- there are also some questions about the care of installation of the suspending grid and whether or not it's leaky,
- removed or damaged drop ceiling panels - I have indeed investigated and even measured airflow changes that happen to confound heating and cooling air flow in offices when occupants remove or partially remove a suspended section to try to tune up their local airflow. Our photo (above left) illustrates the discovery of an unanticipated air pathway between what was thought to be isolated building sections.
- leaks into the space above the drop ceiling risk hidden damage, mold contamination, etc.
- debris in the space above the drop or suspended ceiling may be picked up by and distributed by the HVAC system
If you can be a little more specific with questions I'll be glad to do some research and prepare material for you - it'll help us both. Be sure to let me know the total floor to original ceiling height as well as the floor to drop ceiling height- those will be important model parameters.
Discussion: CP
I'm asking about a drop ceiling in a more general sense, and in a couple things you hit on in your email. I'm a BPI certified home energy auditor and tomorrow I am doing an audit for a family with a bedroom that has a drop ceiling (it formerly was an office).
I'm specifically wondering about some of the dynamics I may want to be on the lookout for during the blower door test. This particular ceiling has insulated tiles and 3-4 inches of well-installed fiberglass batt insulation above the tiles. I'm expecting to encounter some leakage through the grids, however, which I know will compromise the performance of the insulation. - C.P.
Reply: DF
With some building data we can use existing tools to build a table of [theoretical] effects on building energy usage and IAQ when a drop ceiling (suspended ceiling tiles) is installed.
...
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- [1] Armstrong World Industries
2500 Columbia Ave. (17603)
P.O. Box 3001
Lancaster, PA 17604
(717)397-0611, Terms & Definitions, web search 10/21/2011, original source: armstrong.com/resclgam/na/ceilings/en/us/article17707.html
- [2] Armstrong World Industries, Armstrong Ceilings Retailer Guide, PDF brochure, web search 10/21/2011, original source armstrong.com/resclgam/na/ceilings/en/us/request-brochures.html
- Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
- John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
 Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
- Christopher M. Petersen,
West Philadelphia Home Solutions, Email: westphilahome@yahoo.com
- Plastering Skills, F. Van Den Branden, Thomas L. Hartsell, Amer Technical Pub (July 1, 1985), ISBN-10: 0826906575, ISBN-13: 978-0826906571 [purchase at Amazon.com]
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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- 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 Amazon.com and also Wiley.com. See our book review of this publication.
- Building Research Council, BRC, nee Small Homes Council, SHC, School of Architecture, University of Illinois at Urbana-Champaign, brc.arch.uiuc.edu. "The Small Homes Council (our original name) was organized in 1944 during the war at the request of the President of the University of Illinois to consider the role of the university in meeting the demand for housing in the United States. Soldiers would be coming home after the war and would be needing good low-cost housing. ... In 1993, the Council became part of the School of Architecture, and since then has been known as the School of Architecture-Building Research Council. ... The Council's researchers answered many critical questions that would affect the quality of the nation's housing stock.
- How could homes be designed and built more efficiently?
- What kinds of construction and production techniques worked well and which did not?
- How did people use different kinds of spaces in their homes?
- What roles did community planning, zoning, and interior design play in how neighborhoods work
- Gypsum
Construction Handbook [purchase at Amazon.com] H17, Technical
Folder SA920 and PM2, PM3 and PM4, United States Gypsum Company, 125 South Franklin ST., PO Box 806278, Chicago, IL 60680-4124,
- Insulation Types, table of common building insulation properties from U.S. DOE. Readers should see INSULATION R-Values & Properties our own table of insulation properties that includes links to articles describing each insulation material in more detail.
- Weaver: Beaver Board and Upson Board:
Beaver Board and Upson Board: History and Conservation of Early Wallboard, Shelby Weaver,
APT Bulletin, Vol. 28, No. 2/3 (1997), pp. 71-78, Association for Preservation Technology International (APT), available online at JSTOR.
- What Style Is It?: A Guide to American Architecture, Rev., John C. Poppeliers, S. Allen Chambers, Wiley; Rev Sub edition (October 6, 2003), ISBN-10: 0471250368, ISBN-13: 978-0471250364
- ...
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