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Old 02-24-2018, 09:45 PM   #1
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Attic insulation


I want to add insulation between the joists of my attic floor.
I was planning on laying a new layer of thick insulation perpendicular to the old insulation seen in the attached photo.

My questions are:
1. The new insulation I intended on buying is faced, do I need to remove the facing from the old insulation? As you can see from the photo, the current facing is not in good shape.

2. Does it matter what direction the facing "faces"?
I know most say face down towards the interior/warmer part of the house, but I've been told that only really matters for exterior walls. I've also read articles that says it doesn't really matter at all, especially in states like NJ where winters are quite cold and summers are quite humid.

3. Would it be best to just remove the old insulation? The issue I have is Home Depot/Lowe's (by me) do not sell insulation that comes anywhere close to the measurements between my studs that have the appropriate R value for an attic.

Thanks for any suggestions!
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Old 02-24-2018, 11:12 PM   #2
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Re: Attic insulation


I think you can leave the old insulation and the old kraft paper facing in place. And if you are overlaying new batts crosswise, there is plenty of spaces between the facing for any moisture to escape, so I don't really think it makes much difference.

Have you looked at blown cellulose? It's really easy to do and does a better job filling the irregularities etc. You could still just live the old in place.
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Old 02-24-2018, 11:19 PM   #3
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Re: Attic insulation


Hi heather,
Here is the recommended sequence.
1. Air sealing at least the major leaks from house to attic is a top priority and needs to be done before you burry everything with more insulation.
2. The insulation in that picture is ugly, lots of dust and fibers. Yes it can be covered up and often is, but removing it all and replacing it with new is an option. The paper facing normally belongs facing down so another vote for replacing it.
3. When you lay new insulation across the joists you want to avoin the up and down caused by insufficient insulation in each cavity. Adding a thin layer is tedious but can be done or blown in insulation can be used. Baffles would need to be added with blown in insulation.
4. Looks like drywall on the floor to the left, what are your intentions in that area?

Your location would give us an idea as to how much insulation is needed, although more is always better.

I assume your objective is to reduce the heating costs and improve the comfort. There are many easy fixes that can be done DIY.

Bud
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Old 02-24-2018, 11:50 PM   #4
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Re: Attic insulation


The vapour retarder on the wrong side can actually cause condensation in the insulation, allowing moist indoor air to leak through the insulation and hit the cold paper.

This is for cold climates, the barrier always goes on the warm side. climate dictates whether facing interior of house or exterior.

Plus, paper face is garbage, it doesn't work properly, it hasn't been allowed in canada for a long time.

Batts in general aren't great for this application, there will always be some gaps below insulation and around plumbing stacks, fans, etc.

My vote is to:

1. Remove all the old stuff
2. Air seal everywhere you can, black insulation batts indicates leakage
3. Rent a machine and blow fresh cellulose or fiberglass loss fill in. Install baffles to stop it from getting into soffit vents.

I would go for R50, insulation isn't overly expensive.

It's more important to have a well sealed attic than a well insulated one though. R-value when there's air moving through insulation is zero!

When you insulate, the attic becomes colder and the risk of having condensation/rot goes up. So you need to make the ceiling as tight as you possibly can.
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Old 02-25-2018, 12:03 AM   #5
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Re: Attic insulation


To answer some of the questions.
  • I'm in NJ. So cold winters and hot summers.
  • I bought the house last year and all the insulation in the attic has the facing pointing up.
  • No signs of water damage or droppings anywhere on the batts.
  • Intention is to just lower heating costs.
  • The picture angle is weird. This is the floor of the attic. I layed a few particle boards down so people could walk on that section if necessary.

Last edited by 12heather; 02-25-2018 at 12:06 AM.
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Old 02-25-2018, 07:03 AM   #6
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Re: Attic insulation


Ahhh NJ, spent 12 years in Brick, working in Holmdel. For a Maine boy it was a shock and ultimately I escaped. Having lived there does make Maine traffic seem like a pleasure .

Air seal the big leaks, we can help point them out and then get a quote on blowing in cellulose. You can DIY, but sometimes they can do the whole job for about the same price as you would buy materials. Cellulose also fills and seals better than batts. Baffles would still be needed and they can include that in their quote.

Good time of the year to get a bid as winter is ending and summer construction hasn't kicked in as yet.

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Old 02-25-2018, 07:53 AM   #7
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Re: Attic insulation


May I ask a question about vapor barrier on this re-insulation job?

The original insulation was installed wrong with the VB up and it appears there hasn't been a problem with this.

If the present insulation is removed and cellulose blown, does a V B need to be installed some way before the cellulose is installed? If a V B is recommended what V B material and install procedure would be appropriate?
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Old 02-25-2018, 08:18 AM   #8
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Re: Attic insulation


Hi SS,
Certainly if a new vb were to be installed it should be under the insulation next to the drywalled ceiling. But the vb we are shown in the picture is almost totally worthless as a vb so is doing little good as well as little harm.

As to what should be used if a totally new install were done, nothing. Actually a vapor retarder is probably already in place, the paint on the ceiling below. The new thinking is, it is more important to be sure an assembly can dry out than it is to protect it from a small amount of moisture coming through the ceiling. The caveat is, best to have done some air sealing as air can move far more moisture than diffusion.

NJ is also a mixed climate so when the ac is running the vapor barrier should theoretically be on the top side. So way up north where very little ac is used a vb can be added to the warm side and conversely in the deep south where heat is rarely that warm side option moves to the exterior or top of the insulation.

Bud
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Old 02-25-2018, 08:26 AM   #9
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Re: Attic insulation


Quote:
Originally Posted by Bud9051 View Post
Hi SS,
Certainly if a new vb were to be installed it should be under the insulation next to the drywalled ceiling. But the vb we are shown in the picture is almost totally worthless as a vb so is doing little good as well as little harm.

As to what should be used if a totally new install were done, nothing. Actually a vapor retarder is probably already in place, the paint on the ceiling below. The new thinking is, it is more important to be sure an assembly can dry out than it is to protect it from a small amount of moisture coming through the ceiling. The caveat is, best to have done some air sealing as air can move far more moisture than diffusion.

NJ is also a mixed climate so when the ac is running the vapor barrier should theoretically be on the top side. So way up north where very little ac is used a vb can be added to the warm side and conversely in the deep south where heat is rarely that warm side option moves to the exterior or top of the insulation.

Bud
So it's being recommended, even in a cold climate, the paint will suffice if a house was insulated without a V B on the warm side. Thanks
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Old 02-25-2018, 08:46 AM   #10
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Re: Attic insulation


Some paints will perform better than others but that is only important if a vb is needed in the first place. Again, the emphasis on air sealing is what has helped change the views on Vbs.

Here is an excellent read on the subject from a well respected group.
https://buildingscience.com/document...vapor-barriers

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Old 02-25-2018, 04:09 PM   #11
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Re: Attic insulation


the attic is not critical when it comes to vapour barriers, lots of drying potential.

it's far more important to have a tight ceiling.

as previously stated, it's air that carriers moisture, stop air from leaking into the attic and there won't be problems.

Te term vapour barrier is misleading, it's primary role is as a air barrier, vapour diffusion through materials is minimal.
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Old 02-25-2018, 11:34 PM   #12
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Re: Attic insulation


Quote:
Originally Posted by Bud9051 View Post
Hi SS,


As to what should be used if a totally new install were done, nothing. Actually a vapor retarder is probably already in place, the paint on the ceiling below.

Bud
Bud,
I did re-paint the entire house. Do most primer/paints serve as vapor barriers?
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Old 02-26-2018, 06:02 AM   #13
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Re: Attic insulation


We need to consider the difference between a vapor barrier and a vapor diffusion retarder. A carefully installed sheet of plastic is a vapor barrier where a layer or two of paint is some level of vapor diffusion retarder. The different levels are a function of the type of paint used, but all will slow moisture movement to some degree.

Here is an article that may confuse or may help.
https://www.energyvanguard.com/blog/...rrier-Probably

Been awhile since I read it but will do so again if you have questions.

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