# insulation in slanted ceilings



## dhonn (May 2, 2011)

I have a prefab house. I am lowering the ceiling at the high end 1 foot and I was planning on putting 3 inches of insulation between the old ceiling and the new. That is there will be 3 inches at the high part of the ceiling and 1/2 inch at the low side. Then I was going to vent between the to ceilings outside. A carpenter freind stopped by and thought I would be better not to insulate between the two ceiling, leave the dead airspace between the to ceilings. My question is would this cause warm air to get trapped between the two ceilings and cause moisture to build up in there? If I do put the insulation between the ceilings can I just poke holes in the old ceiling for ventulation or do I need to vent out the outside wall?


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## Ron6519 (Mar 28, 2007)

Why are you lowering the ceiling?
How do you plan to do this? With what framing material spanning what distance?
What's carrying the weight on each end?
Ron


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## HomeSealed (Jan 3, 2008)

This sounds like a terrible idea. If you want a new ceiling than rip out the old one. If you are essentially just putting in a "drop ceiling" , I guess that fire, but don't get any wacky ideas about venting this space to the exterior.... What is the point of doing this?


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## Maintenance 6 (Feb 26, 2008)

If your original ceiling has insulation above and a vapor barrier, then adding insulation under it will sandwich the vapor barrier in the middle of an insulation system. That is a sure fire way to create a moisture problem. I guess one question I have is, if you are lowering the ceiling a foot, then how is it you can only get 1/2" to 3" of insulation in the space? Best bet is to tear out the original ceilning finish and insulate properly.


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## dhonn (May 2, 2011)

*Help*



Maintenance 6 said:


> If your original ceiling has insulation above and a vapor barrier, then adding insulation under it will sandwich the vapor barrier in the middle of an insulation system. That is a sure fire way to create a moisture problem. I guess one question I have is, if you are lowering the ceiling a foot, then how is it you can only get 1/2" to 3" of insulation in the space? Best bet is to tear out the original ceilning finish and insulate properly.


 
I was hoping to insulate the house better with out ripping out the old ceiling. If I don't put insulation in will the dead air space cause a moisture problem between the old ceiling and the new? Or would I just better off to just sheet rock over the old ceiling?


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## dhonn (May 2, 2011)

I want to lower the ceilings so I can move the lighting from the walls to the center of the room. The original ceiling does not have enough room to move the fixture there is not very much space between the ceiling and the roof, my son inlaw tried it in his house and hit the roof, same style house. They are the old prefab houses and there isn't much room. If I just lower the ceiling and don't insulate will this cause a dead air space that will cause moisture build up?


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## dhonn (May 2, 2011)

*ceiling*



HomeSealed said:


> This sounds like a terrible idea. If you want a new ceiling than rip out the old one. If you are essentially just putting in a "drop ceiling" , I guess that fire, but don't get any wacky ideas about venting this space to the exterior.... What is the point of doing this?


 
If I lower the ceiling to move the light fixtures to the middle of the room, there is not enough space in the roof to be able to put recess lights in. If I just drop the ceiling and don't put the insulation in, do I need to vent somewhere in the house to get ride of the dead air space or won't that be a problem? should I just vent it out to the hallway. And should there be more than one vent?


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## dhonn (May 2, 2011)

*ceiling*



HomeSealed said:


> This sounds like a terrible idea. If you want a new ceiling than rip out the old one. If you are essentially just putting in a "drop ceiling" , I guess that fire, but don't get any wacky ideas about venting this space to the exterior.... What is the point of doing this?


 
I am lowering the ceilings to be able to move the light fixtures to the center of the room. There is not enought room in the roof to put in recess lighting. If I don't put in insulations will I still have a problem with mositure related to dead space, no air movement. should I vent this space to the hallway, should there ve more than one vent, or won't this be a problem?


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## Ron6519 (Mar 28, 2007)

How are you planning on dropping this ceiling?
Detail the construction.
Ron


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## dhonn (May 2, 2011)

*ceiling*

I am putting 2X4 every 16 inches which are braced to the walls and built hangers to hold it in the center. I have found out not to put insulation above it but what I need to know: is dead air space going to be a problem for me? Should I be venting this into the living space? (such as my hall way ceiling ). Or won't it be a problem?


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## Ron6519 (Mar 28, 2007)

This is such a makeshift bit of construction, it's hard to tell what you need to do to vent or insulate it properly. 
Instead of guessing what to do and possibly guessing incorrectly, I'd either do the traditional, remove the ceiling and add framing and more insulation with the proper venting. Or leave it alone and put in different lighting.
Ron


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