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Finished cathedral ceiling insulation options

Our den is extremely cold and have discovered that the roof has no insulation. Very thin bat insulation exists on the ceiling itself. This we found out when handyman took a look through one of the high hats.

Considering blown cellulose insulation so we don't destroy the Sheetrock, but I am concerned that its particles will come out thru the high hats and ceiling fan and will breath them. No estimate.

Got an estimate -$2,600 to take down one side of the Sheetrock panels and open a hole on the other side to place bat insulation on roof and replace existing insulation with a thicker one. (One side has space to work with, the other side doesn't).

Considering health vs practically tearing the ceiling, which one do the experts recommend?

Asked by Martha Wong
Posted Wed, 03/05/2014 - 02:35

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5 Answers

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Martha,
Your "high hats" (recessed lighting fixtures) are a big problem. If they are leaky enough to allow insulation particles to filter through your ceiling -- and they probably are -- then the fixtures should be removed and replaced with surface-mounted fixtures.

There is no way to fix the problem of recessed can lights in a cathedral ceiling short of removing the fixtures and placing them in a dumpster. Recessed can lights should never, never be installed in a cathedral ceiling. For more information on this issue, see Recessed can lights.

Once you've solved the recessed can problem, you can install insulation on your ceiling. This article will explain your options: How to Build an Insulated Cathedral Ceiling.

Answered by Martin Holladay, GBA Advisor
Posted Wed, 03/05/2014 - 05:23
Edited Wed, 03/05/2014 - 05:28.

2.
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Given that the roof is not insulated, Would you recommend cellulose blown insulation or bat insulation ?

Answered by Martha Wong
Posted Wed, 03/05/2014 - 23:37

3.
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It sounds like this is partly inaccessible attic, partly cathedral ceiling.

Answered by David Meiland
Posted Thu, 03/06/2014 - 01:36

4.
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Martha,
If you are talking about a cathedral ceiling, there are several possible ways to insulate the assembly. Some approaches are vented, while other approaches are unvented.

To learn about all your options, read this article: How to Build an Insulated Cathedral Ceiling.

If you are talking about the floor of an accessible attic, I would recommend a deep layer of cellulose.

Answered by Martin Holladay, GBA Advisor
Posted Thu, 03/06/2014 - 05:31

5.
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Dense packed cellulose will actually airseal itself around and against fairly wide openings, cracks, seams, etc, but the law requires clearances so the cellulose is out of range of the heat of recessed lighting. Your problem is not the fugitive particulate, it would be the combusiton of cellulose that is againt and possibly inside the hot boxes.

Here is an online Technical Bulletin from one of the country's largest cellulose manufacturers:

http://www.nationalfiber.com/docs/TechnicalBulletinOnChimneysVentsRecess...

There are foam and metal boxes, as well as compliant light cans, but this just isn't done anymore:

https://jrproductsinc.com/shop/pc/10-x-10-x-12-Insullite-ProPlus-Vented-...

Nothing but horror stories abound in the articles and research referenced on this website with the use of FG batts in cathedral ceiling assemblies.

Answered by flitch plate
Posted Thu, 03/06/2014 - 11:38

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