# Insulation options for 2x6 roof rafters



## dliuzza (Apr 4, 2021)




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## Nealtw (Jun 22, 2017)

Why does you insulation stop at the wall, are you thinking you can use venting from under the house?


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## dliuzza (Apr 4, 2021)

I’m not done insulating. Are you talking about the insulation in between the floor joists?


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## dliuzza (Apr 4, 2021)

Venting from under the house? How would that even be possible?


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## Nealtw (Jun 22, 2017)

I am asking about the fire stop?


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## dliuzza (Apr 4, 2021)

The only insulation that is shown in these pics are in the floor. Nothing in the walls, yet.


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## Nealtw (Jun 22, 2017)

dliuzza said:


> The only insulation that is shown in these pics are in the floor. Nothing in the walls, yet.


Why would you insulate the floor before you did the fire stopping?
Fire Travel in Balloon vs Platform Frame Construction - YouTube


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## dliuzza (Apr 4, 2021)

There are fire blockers below.


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## dliuzza (Apr 4, 2021)

This is also rockwool insulation which is highly fire resistant.


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## Nealtw (Jun 22, 2017)

dliuzza said:


> There are fire blockers below.


Top bottom and floor between when open, the house is a fire trap for you, your family and the firemen.


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## Nealtw (Jun 22, 2017)

dliuzza said:


> This is also rockwool insulation which is highly fire resistant.


Ask your fire department if they like that.


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## dliuzza (Apr 4, 2021)

There’s a fire stop just below the floor joist.


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## Bud9051 (Nov 11, 2015)

Sorry if I'm slow, but addressing the initial question, the top picture shows a rafter cavity going down to the top of the wall. Will there be any provision for ventilation?

Bud


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## dliuzza (Apr 4, 2021)

Yes, I’m looking for a solution since my soffits are closed off. I was thinking of adding round vents just above the top plate between each bay then opening up the outside under the soffit.


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## Missouri Bound (Apr 9, 2011)

Why are you insulating your rafters? Are you planning to make that living space?
Unless you are there is no reason to insulate an attic.....just the floor / ceiling of the living space.
And if you ARE going to make that living space, you need ventilation from soffit to ridge.
So you need soffit vents, ridge vents and rafter baffles for each bay.


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## dliuzza (Apr 4, 2021)

Yes. It is a living space.


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## dliuzza (Apr 4, 2021)




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## Bud9051 (Nov 11, 2015)

Can you give us a picture of the outside of the house in that area.

Bud


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## dliuzza (Apr 4, 2021)

dliuzza said:


> View attachment 658172


 You just couldn’t see it in the previous pic. There’s also blocking sealing up in between the openings in the floor joists under the knee wall.


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## Bud9051 (Nov 11, 2015)

Why have you concluded you can't do soffit vents?


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## dliuzza (Apr 4, 2021)

Bud9051 said:


> Why have you concluded you can't do soffit vents?


I haven’t. Just not sure where to add them from the inside.


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## dliuzza (Apr 4, 2021)

dliuzza said:


> I haven’t. Just not sure where to add them from the inside.


I was thinking here. Just not sure how big and how many per bay. On the outside I was thinking of cutting open the bottom of the soffit and adding vents.


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## dliuzza (Apr 4, 2021)

BTW there is a ridge vent already in place.


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## Bud9051 (Nov 11, 2015)

If those circles go through to the overhang cavity that is an option.

Now, a more difficult topic. 2x6 rafters are not deep enough for the recommended amount of insulation unless you filled them solid with rigid insulation, allowing for the vent channel. In some cases the rafters are filled as best possible and then a layer of rigid is added before the drywall.

Will there be inspections, then codes need to be followed?

Bud


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## dliuzza (Apr 4, 2021)

I’ll never achieve what is required. Just want the best option. There is already 3/4 of an inch to allow for air flow. Leaving 5 1/4 of space.


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## oggy bleacher (May 3, 2011)

I had rafter bays like that and had to lay the fiberglass batts sideways since the width was all wrong. Stapling was a pain. And i took the facing off the insulation since in made no sense to use perforated radiant barrier behind faced vapor barrier insulation and I couldnt find any unfaced insulation. I used foam rafter baffles but basically the same result as your approach. And I sawed the soffit to add 10 vents.
But then I finished the whole ceiling with rigid poly insulation and taped the seams with foil tape. But I also had a grid of furring strips so the rigid fit between the strips so any sheetrock would be flush, although I ended up using tin ceiling tiles nailed into the strips.
It was tedious but was the maximum insulation possible. You might furr out the area above 7' to add more insulation without losing headroom.


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## colin123 (Oct 9, 2014)

I did this with my house I put 6 inches of Ridgid foam on top of the roof deck if you need a new roof this is a great way to go because you have no thermal bridging from the rafters.


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## Jim Port (Sep 21, 2007)

It looks like a lot of water damage. Have the leaks been fixed?


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## dliuzza (Apr 4, 2021)

Jim Port said:


> It looks like a lot of water damage. Have the leaks been fixed?


Yes


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