Insulating ceiling with attic

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Old 05-31-20, 01:53 AM
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Insulating ceiling with attic

When I tore down the ceiling, there was no insulation in the rafters.

I am going to put r38 in the ceiling joists. Is it recommended to also install r13 into rafters above the ceiling?

Not sure on how to effectively use insulation in an attic
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Old 05-31-20, 05:51 AM
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Above the ceiling No.
But in the rafters that slope up to the flat area of the ceiling Yes

Also do you have soffit vents?
There should be an air space between the insulation in these rafters down to the soffits.

As important as insulation is ventilation in an attic. I can see what looks like a gable vent but cannot tell how big it is.
 
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Old 05-31-20, 06:25 AM
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@ Manden unless I missed something I think you got that backwards. In a typical attic the insulation goes in the ceiling below, the attic floor, not in the rafters.

DIY4 sounds like a moderately cold climate with r-38, but tell us where you are.
Yes baffles should be installed in every rafter channel and there should be adequate soffit venting matched with one of the high vent options.

Bud
 
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Old 05-31-20, 06:34 AM
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I think we are getting our terms mixed up, no insulation in the roof joists just below the shingle deck!
 
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Old 05-31-20, 07:01 AM
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Thanks for the info. I am in Maryland. When I looked up the stuff is said r38-r60. To get energy efficiency in Maryland I need r49, so I may go to that level because why not.

And it sounds like only insulation in ceiling joists/attic floor.

And I don't think I have soffit ventilation or at least not that I can see I may need more exploration
 
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Old 05-31-20, 07:03 AM
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Bud9051

He did not ask about insulation in the rafters above the flat ceiling (ceiling floor) as he is putting in R38.

If I understood his question it was should he put insulation above this in the rafters next to the roof deck and my answer is No

If you look at the photo he has a flat ceiling area and also a sloped section.
In the sloped section the insulation has to go between the rafters with an air space.
 
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Old 05-31-20, 07:06 AM
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Here are the pics for this project if you want the whole picture.

https://www.doityourself.com/forum/w...r-ceiling.html

Insulation goes in the rafters below the ceiling... NOT in the rafters above the ceiling. Chutes can be used to keep insulation away from the roof deck in the attic, (if you need to maintain ventilation) where you might use cellulose or blown fiberglass.
 
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Old 05-31-20, 07:16 AM
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There are a few slopes in the room directly tired to the rafters where I am going to have to settle for less than r38/49 depending what route I go. I am thinking r49 is going to win because why not

I do not have soffit ventilation. I don't know what this is called and I tried to get it in picture but 2 triangles with like 3 slots at the top of the peek of the roof. 1 opening on the west side of house and 1 on east side. I believe that is only ventilation I have for attic space I am seeing
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Old 05-31-20, 07:22 AM
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If you are going to meet building codes there are some issues you need to search.
1. your minimum requires r-value.
2. Is there a reduced requirement for a smaller amount of slopping ceiling?
3. Whatever the final required number, fitting it into the slopes with ventilation will be a challenge.

Bud
 
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Old 05-31-20, 07:23 AM
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Also rereading these responses over and over trying to understand. You said the rafters below the ceiling I need an air gap between insulation and roof wood? Those are 2x6 rafters, if I use r13 in those location and I am using faced Batts and staple the paper to the wood would that leave enough of a gap. Or the fact I do not of soffit venting it appears the gap is not needed because the gap would only be to allow the soffit vent to allow airflow into and out of the main attic cavity
 
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Old 05-31-20, 07:47 AM
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Check you ventilation!!!
The U.S. Federal Housing authority recommends a minimum of at least 1 square foot of
attic ventilation (evenly split between intake and exhaust) for every 300 square feet of attic floor space.
 
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