Questions and answers about suspended or drop ceilings.

This article series 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.

Q&A About Suspended Ceilings / Ceiling Tiles

These questions and answers about the materials, installation, or troubleshooting of suspended ceilings or "drop ceilings" were posted originally

at CEILINGS, DROP or SUSPENDED PANEL - be sure to review that information.

[Click to enlarge any image]

 

On 2018-07-09 by Anne Whitehouse - Movement in my ceiling boards is causing cracks in the ceiling plaster

Movement in my ceiling boards is causing cracks in the ceiling plaster. How can this be remedied ?

 

On 2018-05-01 by (mod) -

Anne, we need to have a more detailed understanding of how your ceilings are constructed. Certainly this doesn't sound like a suspended ceiling problem.

Indeed sometimes people cover an old plaster ceiling in poor condition by installing a suspended ceiling. But I'd want to diagnose the source of movement first.

Take a look at CEILINGS, PLASTER, LOOSE HAZARDS for more advice that fits your situation.

On 2018-05-01 by Andrew Bramall - wind blowing over house causes ceiling movement

We have a potential situation....wind flow over a new portal frame classed pitched roof causes air pressure difference above the roof structure (Bernoulli's principle).

Air trapped within ceiling void acts as a mass...making the suspended ceiling grid move and rattle.What is that easiest solution to this??.
Please contact 01785-256098 07803-266607 1st of May 2018

On 2018-05-01 by (mod) - Bernoulli effect on roofs causing ceiling air movement

Interesting engineering question, Andrew and not my expertise.

I would think, however, that the solution would be either a more-nearly-perfect seal of the building attic or ceiling cavity OR a system to permit air pressure equalization.

I would start with some smoke tests to find the points of air leakage.

On 2018-01-28 by Alan - high school in the Sunbelt has a celotex style dropped ceiling with no insulation

Our local high school in the Sunbelt has a celotex style dropped ceiling with no insulation. Between the flat rubber roof that is supported by metal trusses and the ceiling is NOTHING. There is no one shred of any insulation.

When questioned, the school maintenance manager states that there is no insulation because the tiles have to be porous because the HVAC system sucks the air out of the void between the ceiling and roof to heat or cool! Has anyone heard of such a supposed HVAC commercial system or is his full of BS?

On 2018-02-01 by (mod) -

Alan

Some buildings use insulating foam atop the roof, between the roof upper surface and the roof covering membrane.

But what you report from the school maintenance manager makes no sense to me. I suspect the manager is better informed that that but is perhaps not a good explainer. For example, some HVAC systems use the area above a suspended ceiling as a giant supply or return air plenum (not the best design but common).

But that would never be an argument for requiring "porous" ceiling tiles. Baloney!

On 2017-04-24 by Anonymous - isn't a suspended ceiling almost by definition a porous ceiling?

Yup, I'm looking at the windows / doors as well. But isn't a suspended ceiling almost by definition a porous ceiling? But I understand what you're saying.

On 2017-04-24 by (mod) - suspended ceilings are "porous"

Yes suspended ceilings are "porous" but just how much of a heat loss problem occurs there depends alot on what's above the suspended ceiling grid. If there are air leaks to the outdoors (through openings into an attic for example) through the ceiling then that needs to be addressed. If the ceiling is air tight and above it is an attic then one would do as well to insulate the attic floor.

If you can find someone to contribute an IR scan or THERMOGRAPHIC scan of the building that'd be diagnostic; else the risk is spending time and money on items in the wrong order.

See ENERGY SAVINGS PRIORITIES - what is the order in which we should invest in building energy savings measures https://inspectapedia.com/heat/Energy_Cost_Reduction_Priorities.php


See AIR LEAK DETECTION TOOLS - at https://inspectapedia.com/Energy/Air_Leak_Heat_Loss_Tools.php

Here is a list of energy savings articles ENERGY SAVINGS in BUILDINGS https://inspectapedia.com/Energy/Energy-Savings.php

 

On 2017-04-23 by Anonymous - how to reduce ceiling heat gain

Thanks I already guessed #2 probably would be a problem, #1 and #3, I would not have guessed.

Basically, I'm a pastor from the Midwest (where we believe in insulation) recently transferred to Southern California to a financially challenged parish and trying to reduce the impending AC costs in a portion of our former school, now converted into our parish offices, the retrofitted offices having the famous drop ceilings. I see the nightmare of putting down the bat insulation.

On the plus side, we have nothing but shade-less south-facing open space on our former school (ideal of solar panels). But financially strapped, I figured I'd first try to find ways to lower our electricity consumption and then look to find ways to finance covering said roof with solar panels.

But it might just be worth it to look for the financing to put up the panels rather than deal with retrofits that would be hard, probably ineffective and perhaps even dangerous.

On 2017-04-23 by (mod) -

Start with looking for air leaks - that problem will swamp a problem of inadequate insulation.

On 2017-04-23 by Anonymous - blow in insulation over a suspended ceiling?

Would it make sense to blow in a layer of insulation (cellulose or fiberglass) to increase the R value of a drop ceiling? Would there be subsequent dust problems (which in the case of fiberglass could be hazardous)?

On 2017-04-23 by (mod) -

Anon:

I wouldn't blow insulation over a suspended ceiling because

1. It may bury electrical connections and boxes that should not be covered - a fire hazard and a code issue

2. It will make accessing and repairing anything above the drop ceiling a hell of a horrible job

3. IF there are HVAC air passages in the ceiling - as in some commercial building designs for return air - those would be blocked.

However IF you want to improve the R-value of the ceiling there are a couple of options.

- easiest: if space permits replace the existing ceiling panels with insulating panels of the same dimensions; you can find thick insulating ceiling panels that will drop in place if there's enough room

- harder: a DIY approach is to lay fiberglass batts over the ceiling - labor intensive and a horrible job

On 2016-10-21 by Joy Antonio - whether or not it helps at all to put up a drop ceiling if you don't finish the edges

In an argument with my brother about whether or not it helps at all to put up a drop ceiling if you don't finish the edges. I believe the heat is still going to rise and was told I have no common sense. He believes it will slow down heat loss with only the middle finished. Who is right?

On 2016-10-22 by (mod) -

Good argument, Joy. In general I agree with you. If you consider that a 1-inch gap around the ceiling of a 10 x 12 room is 1 x (10 + 10 + 12 + 12) = 44 square inches of opening - through which warm air is going to rise - it's about like leaving a window open. The result is that the benefit of the drop ceiling in heat loss reduction is likely to be substantially less than if the whole ceiling is finished.

This opinion is supported by objective data I've collected in the field. For example, leaving one drop ceiling tile out (as shown in the article above) is enough to cause considerable trouble for heating or cooling efforts of the space below the ceiling, more-so if the ceiling space is being used for an air return plenum.

On 2016-06-28 by Carlis P. Sweat - R-value of Thermal Insulating Mgo Fiberglass Acoustic Ceiling Tiles with foil back

What is the R-value of Thermal Insulating Mgo Fiberglass Acoustic Ceiling Tiles with foil back

On 2016-06-28 by (mod) -

It's a bit doubtful that you can trust any answer to your question, though we give R-values at

https://inspectapedia.com/insulation/Insulation-Values-Table.php

That's because so much depends on air leaks; depending on how the ceiling was installed, air leaks can overwhelm R-values.

On 2016-02-11 by April Henry - possible to move inside of a drop ceiling to escape bad guys.

I write mysteries, and am setting a book at a (made up) shopping mall. I was wondering if it would be possible to move inside of a drop ceiling to escape bad guys. Can you put your weight on the supports? Would you fall through if you put your weight on a tile? Would you have to be crouched over? Would love to hear what you think! April@aprilhenrymysteries.com.

On 2016-02-12 by (mod) -

SOME (not) most drop ceilings have enough space to crawl, but as the ceiling grid is hung by wires it would collapse unless someone has first laid down a walkway or crawlway of planks. And the wire system would have to handle the added weight. So in some cases yes. It's within poetic license.

You'd be crawling not walking.

On 2015-11-08 by matt - problem with gaps in suspended ceiling

Installing a drop ceiling in our basement. I purchased some boxes of USG ceiling grid from a guy and it's primered. I painted it all but when we started the install the main runners lock together and have a gap on bottom finished edge. There is no way of closing the gap up unless we trim all the tabs to let them slide further into slots. The box says Donn system rmx 12d. I'm lost and cannot find any info on this system.

On 2015-11-09 by (mod) -

Matt:

The Donn brand ceiling suspension system is widely used and is marketed by US Gypsum. If you contact US Gypsum(USG) they'll be happy to send you a user's guide for this product line.

Call USG at 800USG.4YOU

Ask for the "Donn® Brand Suspension Systems Accessory Product Guide" that contains a user's guide.

Or use our page bottom CONTACT link to send me your email and I'll send you a copy of the PDF.

 

On 2015-03-12 by B - Do suspended ceilings typically found in older commercial building commonly contain asbestos?

Do suspended ceilings typically found in older commercial building commonly contain asbestos? The edges of the panels are brown, with the presenting surface being white with those typical black dots all over. Not sure of age....possibly 70s. Thank you!

This is at a relatives workplace. The ceiling is not in good condition, has water damage, some broken tiles. If it is not being renovated is it likely that much asbestos would be released into the air when it isnt being actively disturbed?

In Canada if that makes any difference

The year the building was constructed was 1978. It is a suspended ceiling.

On 2015-03-13 by (mod) -

My OPINION_ without knowing a darn think about the site - is probably not. But really, no one can assess an environmental risk by an e-text.

Indeed there are some suspended ceiling panels that were made entirely of wood products and don't contain asbestos.

But given the age of the property, if the ceiling is a mess, is being demolished, breaking up, falling down, and if there are no identifying stamps or marks to name the material and its manufacturer, it'd be prudent to have a sample tested by a certified asbestos test lab. It's not a large cost - abut $50. CDN.

On 2014-11-29 by R L MURPHY - fix a suspended ceiling with too little space

I have to replace 2x2 acoustical tile in suspended ceiling in basement. There is about 1 inch clearance from above the grid because of [2] Air conditioning ducts that fill in that opening. How can I even get a tile in there with no clearance? I can push duct up a couple inches on 2 sides but the other sides dont budge. Dont like breaking any more tiles trying.

On 2014-11-29 by (mod) -

R.L.

What I do when space is very tight in a suspended ceiling because of ductwork or other obstructions is to work the new ceiling tile in from a side where there is more free space. Remove ceiling tiles near the tight area but in an area where there is indeed working space to get the ceiling tile up into the ceiling, then into a horizontal position.

Then just slide the tile over into the cramped area where it's needed. With this approach you don't need much more than about 1/2" of free space besides the thickness of the ceiling tiles themselves.

...

Continue reading at CEILINGS, DROP or SUSPENDED PANEL - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ASBESTOS CEILING TILES
• ASBESTOS TESTING LAB LIST if you need to test a ceiling panel for asbestos
• CEILINGS, PLASTER, LOOSE HAZARDS
• CONCEALED SPACE FIRE CODES - as suspended ceilings can form an accessible concealed space in buildings

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