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Discussion Starter #1
I have a small one story house in Central Florida that has vaulted ceilings inside so the only space for insulation is the 6" between the roof and ceiling. Right now between each truss there hole at the end for venting but it has no insulation currently. The roof is in good shape and is the rolled on type. During the summer the inside ceiling will get hot and the A/C runs more than it should. We recently upgraded our windows and our A/C is still running hard. We are hoping to do the project ourselves since we don't have much money but we are not sure the best way to fix this problem. Any suggestions would be great. I can post some pictures if my description is confusing.
 

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Discussion Starter #6
Is that joist space vented?

You could dense pack that area but doing so will convert it to an un-vented assembly and that can be problematic.
Yes, each joist section is vented at the end. There is no venting at the peak. The issue I see is the vents are only 2" holes with mesh so the inside ceiling still get's really hot. I know installing a vent at the peak might help but that seems harder than blowing insulation up in between each joist. I'm assuming for blown insulation that I would just need to get a long tube but the problem would be the scissor supports about half way up.

How are most of the houses like this insulated? I see many small block houses with very low pitched roofs or flat in Central Florida and Miami so they have to have something between ceiling/roof.
 

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Another way is with SIP roofing panels. Since you have little money and the roofs in good shape this may be out but it would add a whole lot of insulation value and save in the long run on cooling cost.
http://www.insulatedbuildingpanels.com/
 

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Discussion Starter #8
Another way is with SIP roofing panels. Since you have little money and the roofs in good shape this may be out but it would add a whole lot of insulation value and save in the long run on cooling cost.
http://www.insulatedbuildingpanels.com/
That looks like a good solution but I doubt I could afford it. I can probably only afford around $700-1000 for this project.
 

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Do not dense-pack cellulose in it. Are the HVAC ducts in there?

Gary
 

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Discussion Starter #12 (Edited)
What I said earlier.

Foam to the interior wall and re-cover with drywall.

Leave it vented.
If I did go with rigid foam board, what R value/Thickness would you recommend. Also, would increasing the size of the vents help any?

What is the main issue with packing in cellulose insulation?
 

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If I did go with rigid foam board, what R value/Thickness would you recommend. Also, would increasing the size of the vents help any?

What is the main issue with packing in cellulose insulation?
The more the better. Code would likely call for R-38 which is going to be 6" of Poly-iso.

Dense packing cellulose can create a moisture and rot issue.
 

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Discussion Starter #15
It sounds as if you have "scissor" trusses? Is there access/room to crawl around up there? Describe, please.

The roofing is a vapor barrier to d.p. cellulose; http://www.buildingscience.com/documents/insights/bsi-043-dont-be-dense?searchterm=attic+fiberglass+batts+in+flat+attic

Gary
I'm back to trying to figure out this issue since the summer is upon us and our A/C is running constantly. Our whole roof is similar to the image below. We have the roofing surface, deck, then open space which is probably only 6-8" x 12-18" between each truss and then the drywall for the inside. There is no insulation where the picture shows it Between each truss there is a vent similar to the picture. People have recommended taking down the drywall inside and adding insulation which we don't want to do. I'm wondering if just rolling on one of those white roof coatings that reflect the heat will be enough.

 

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If the coating worked you would see many many more white colored (coated) roofs... vent the roof (add ridge vents) and insulate to minimum code requirements for your location (R-30) http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

More on unvented, expect a 10% service life reduction for asphalt shingles; http://www.buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation?full_view=1

Hot climates; http://www.buildingscience.com/documents/reports/rr-9801-vented-and-sealed-attics-in-hot-climates

Check with your local AHJ, venting may be required.

Gary
 
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