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VC_YamahaRider
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# Posted: 28 Sep 2015 08:41pm
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I am having trouble finding a similar cathedral ceiling set up as mine on this site so I figured I would throw my set up out there to see if anyone had any ideas on how to insulate.
I am concerned about moisture. I have a small 24x18 cabin with a 10/12 pitch ceiling. The rafters are 2x6's 24" on center and there are purlins running across the top of them. On top of the purlins is the foil bubble insulation and then on top of that is the metal roof. My original thought was to put just R-13 fiberglass in so that there was plenty of air space between insulation and the metal roof to keep it dry in there. I do have vents in the peak and the soffit. I can't really put the foam baffles in because I have nothing to nail them to since normally you nail them to the underside of roof sheathing (I have metal so can't really nail them to that). Now after doing some research I am not sure what to do. I do not want moisture problems. From what I read, the fiberglass insulation can't handle moisture.
I will only be using it 3 or 4 weekends in the winter. It will be used mostly in the Spring and Fall during the weekends. I am in Ohio so it does get cold her in the winter.
Any help would be greatly appreciated. I was planning on insulating this weekend coming up.
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bldginsp
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# Posted: 28 Sep 2015 10:29pm
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Sounds like you have a good setup to pass air over the top of the insulation. Baffles are good- they ensure that you have a consistent air space. Glue them in with contact construction adhesive, heck use duct tape- once the ceiling is in place they won't go anywhere. But be sure that every bay can bring air in the bottom and let it out at the top. You need cross-ventilation to get rid of condensed moisture. Good luck
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VC_YamahaRider
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# Posted: 29 Sep 2015 08:46am
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Should I run the baffles all the way up from soffit to peak? I know in a typical non-cathedral attic you just put one baffle in on the soffit end in each rafter section. I feel that in my situation, I need to put them in from soffit to peak to have a consistent air channel all the way up and to keep moisture getting to the insulation. The only problem is that get's expensive.
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bldginsp
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# Posted: 29 Sep 2015 09:01am
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You don't need the baffles at all if you know that there will be an air channel. With R13 in a 2x6 there will be 2" extra space, so if you place the insulation carefully you will have the space you need. One way or the other the air must be able to flow across the space from bottom to top, or it won't move at all.
Baffles make it easier in some situations. If I were you I'd consider using baffles with R19 insulation just for the added R value. R19 has 5-1/2" loft, which takes the whole 2x6 space, so the baffles would be necessary. But R-13 is 3-1/2", leaving you 2" to work with.
As you said sometimes baffles are best used just at bottom and top to ensure that the insulation doesn't block the air passages at the eave or ridge. Depends on your design and configuration.
The air must flow.
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VC_YamahaRider
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# Posted: 29 Sep 2015 09:22am
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Okay, good information.
I think I will just go with the one baffle at the soffit and just use the R-13. I just priced it out and if I changed to R-19, the price would go up $230 for just the insulation and another $156 for enough baffles to extend the whole rafter space. I already have the R-13 purchased so I will just go get enough baffles to put at the soffit end.
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