# Wierd Null Area in Attic - New Construction



## enochian (Jul 1, 2015)

This space seems to be between a toilet and a hall closet on my second floor.


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## Windows on Wash (Aug 30, 2011)

No need to fill it but it should be sealed off from the attic space with some foam board and sealant. 

At that point you can cover it back over with the fiberglass. 

I would also mark it out so that you don't step on that in the future. That would be a disastrous first step.

See page #20. http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/ba_airsealing_report.pdf


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## enochian (Jul 1, 2015)

What about nailing in a floor board?


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## 47_47 (Sep 11, 2007)

That chase is acting like a chimney. You need to put on an air stop like a piece of sheet metal, then insulate over the top.

Looks like Windows beat me to it


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## enochian (Jul 1, 2015)

What if I just fill in the whole thing with pink insulation?

The pink would be a different color than my white.


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## ZTMAN (Feb 19, 2015)

Looks like someone was trying to make a laundry shoot. Is you washing machine near the bottom of the cavity?


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## enochian (Jul 1, 2015)

No.

I think its just some extraneous space left over.


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## ChuckF. (Aug 25, 2013)

You can use that dead space someday to build a deep storage cabinet on one side or the other, or a secret stash.


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## enochian (Jul 1, 2015)

I thought about it. But its behind a closet on one side, and a toilet on the other.


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## enochian (Jul 1, 2015)

1. Per code, is there any issue if I fill it up with loose pink?

2. Where do you buy the loose white fiberglass? Home Depot doesn't have it.


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## Bud9051 (Nov 11, 2015)

Fiberglass insulation is what they make air filters out of, it isn't the best material for blocking air currents. You need a fire rated stop in the attic, sheet metal as mentioned, or drywall. If you insulate over the top of whatever you put in the attic then there is no need to fill the cavity with insulation. The stash idea is actually a good suggestion as homes accumulate lots of valuables that could be kept out os sight.

Bud


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## enochian (Jul 1, 2015)

Ok I will do the sheet metal.

Where do you buy loose white fiberglass?


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## Bud9051 (Nov 11, 2015)

The blown in insulations require a machine to fluff it up and blow it in. Big box stores often loan (with a minimum sale) or rent the machines. If they don't have it then check for a specialty business that deals with insulation, maybe (?) they would sell some. But any type of loose fill insulation would work. cellulose would be my choice, but that may be a regional preference.

Bud


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## enochian (Jul 1, 2015)

How do you get an air tight seal with the sheet metal in the above photo?


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## Bud9051 (Nov 11, 2015)

I really can't see the framing details, but the edges of the sheet metal can be bent up or down to provide a nailing surface if there isn't something. The sell a fire rated caulking to seal the metal to wood. 

The suggestion about using something stronger in case you or someone else steps on this area is good. Same caulking and then cover with sheet metal or drywall. 1/2" drywall qualifies.

Bud


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## enochian (Jul 1, 2015)

If I want to insulate the weird area for sound, how do I do it?

Do you need a vapor barrier?


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## Bud9051 (Nov 11, 2015)

Bales of insulation that are meant to be blown in are difficult to fluff up, but not impossible. The other method to fill that cavity would be batts or say 6" insulation cur to length and pushed down from the top, or up from the bottom, whichever.

I just don't have the whole picture to guess for other options.

Bud


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## enochian (Jul 1, 2015)

I am going to stuff it with batts of rockwool then put some sheetmetal, OSB or drywall on top.


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## mikegp (Jul 17, 2011)

Why would you waste time and money filling the space? You just cover the space on the top, air seal with some canned spray foam, and throw insulation OVER it. Filling that space would be the same as filling an interior room on the second floor with insulation. You don't fill the room, you just insulate the ceiling. So make a ceiling and insulate it. 

If it was my house, I'd be extending the closet. Space is too precious to just throw away. My builder thought it was a good idea to build an angled wall in the back of my entry closet. No way was I going to let that fly. I cut a small inspection hole thinking I'd find pipes, ducts, wires... nothing.


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## enochian (Jul 1, 2015)

Soundproofing. Also firestop caulk is a better product than spray foam.


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## mikegp (Jul 17, 2011)

I don't know if that's worth it, but it's your house. If there's a bathroom and a closet on either side I wouldn't care too much. Plus just dumping insulation in there isn't going to sound proof much. Especially considering there's probably more shared walls between rooms than that tiny chase. 

Also, they make make a fire rated spray foam. It is reddish when sprayed.

That is an odd space, maybe the builders originally intended it as an hvac chase or something. What's under it? You do have a rare opportunity to easily pass things from 1st floor to attic if it's a two story house. Wires, pipe, ducts, etc.


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## enochian (Jul 1, 2015)

That's merely a fireblock foam, not firestop.


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