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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.
What is a "suspended ceiling" or "drop ceiling"? According to Armstrong Corporation, a manufacturer of suspended ceiling products, [edited and paraphrased]
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.  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".
Suspended Ceiling / Drop Ceiling Materials, Choices
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:
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.
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:
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
[Modeling & data collection are in process, CONTACT us to contribute information.]
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.
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:
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.
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.
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.
Questions & answers or comments about suspended ceilings or "drop ceilings" in buildings
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Technical Reviewers & References
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