Attic insulation question


I am finishing a 3rd floor walk-up attic/room. I installed Durovent between the rafters for ventilation and then insulated between the rafters. I built a 3-foot high knee wall that closes off the space under the rafters near the eaves where the rafters go down to the floor level. That space will be inaccessible -- not used for storage and with no access door.
The rafters, ceiling, and knee wall will be sheetrocked above and around the living space. But there will be no sheetrock covering the paper-faced insulation that is between the rafters behind the knee wall in the to-be unused space.
My question is, would there be any pros or cons to adding some type of plastic or Tyvek or whatever over the paper-faced insulation between the rafters in the unused space behind the knee wall? Maybe it would serve as an additional vapor barrier? Or, could that cause a problem by having both the paper facing and the plastic/Tyvek vapor barrier?
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JayTKR wrote:

I would expect there to be no insulation between the rafters outside the knee wall. The insulation would go down the wall and across the joists from the wall to the outside wall below. The airspace above it would be ventilated to the outside. Otherwise, the knee walls will tend to be cold, since there is an unheated airspace outside them (even if unventilated).
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Keep in mind that 6 mil plastic is a vapor barrier, and Tyvek/ housewraps are WATER barriers. That is why the former is code for interiors behind drywall and the latter is code for exteriors. If you cruise the new development sites, you will often see houses on the market with unfinished, but insulated, garages with the insulation protected by plastic film. That should be a good clue as to what will work best in your project.
Joe
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on 11/30/2009 12:26 PM (ET) JayTKR wrote the following:

It might be overkill.

I would think not there either.
--

Bill
In Hamptonburgh, NY
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on 11/30/2009 2:14 PM (ET) willshak wrote the following:

Just an addendum. I would have a nondiscript access door on each knee wall for access for inspection or repair.

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Bill
In Hamptonburgh, NY
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"JayTKR" wrote

To bad. Had an aprtment once were the 3rd bedroom was a 'finished off' attic. The eaves made great storage. What we did was put up caffee curtin rods all along it and lots of pretty and simple gingham check. Insulated but didnt finish back there, yet made great storage.
Looked nicer than it sounds against the solid wood floors. Ceiling was insulated and drywall between the beams with a little molding to make the seams look nice, so you had about 1 inch of wood rafter showing.

Ower used cloth tacked up to keep any insulation dust in. More wasnt needed and might have created a problem.
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That's an interesting idea, and it is something that I may want to think about for my own house where I am living.
I neglected to mention that the attic that I am finishing now is in a property that I bought that will be rented out to tenants. Also, when I bought the property the attic was already "started" by the previous owner. Basically, the framing was already done, including the knee wall and a large closet area. Since it will be a rental, I wouldn't want to have any exposed insulation and I'd rather just close off the potential additional storage area behind the knee wall.
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Jay-T wrote:

Knee walls, yes. Inaccessible dead space, no. Make a screwed-down access cover, and make it such an obvious pain to remove that the renter will never mess with it. Or get inventive, and make an invisible access panel, with seams hidden in trim, or covered with a shallow 'built in' bookcase or something. Attic room = playroom in most cases, so toy shelves would be a big plus to prospective renters.
-- aem sends...
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The access question is something that I did think about. The framing for the knee walls did leave two places for access panels to be placed. But, I couldn't think of a way to create access panels that wouldn't invite tenants to open them up. What I ended up decided to do is leave the framing the way it is, but just sheetrock over the access areas without creating an access panel. I ran the wiring around the framed out access areas,and I took pictures of it all, including the wiring, before doing the sheetrock. Then, if I ever do have to gain access to those areas, I'll know where they are. I would then have to cut out the sheetrock at that time and create a removable access panel when I'm done.
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"Jay-T" wrote

I can go in more detail too if needed. BTW, sorry about the burp. I see Cox sent the message 4 times.

Yeah, they might damage things back there.
The apartment attic I used, was a 'diamond in the rough' level. It spanned 1/2 the house so was a HUGE room. Access was from a pull down ladder in the kitchen. No separate heat but we were looking at adding something. The pull down was over the oil radiator in the kitchen, so it wasnt totally intolerable for Clemson SC area. When it got really cold, I slept on a sofa downstairs but that was only 2-3 weeks or so a year.
There was no 'closet' so with permission, I made one from more of a matching gingham materal. I used round rods saved from old brooms (grin, they didnt toss much away so had them stored up there) and the existing wood beams with spare hardware they had. One side was a suspended rod about 4ft or so long, and the other was a double tier (about 3ft) so you had 'shirts and jackets on top' and 'pants or skirts' below. Used a 2x4 with a U shaped 'dip' for the center of the 4ft bar (mounted on a little wood block about 6"x6" at the foot). Basically wanted to be sure it didnt stress the rafter hangers over time for that longer run. The shorter section was nailed to this and another 2x4 support ran on the outerside up to a abut a rafter with a / cut to fit. 4th bar across the front gave me a 'door' to close (again, just material you sewed a pocket to slide through the bar like the rest but even easier since didnt have to angle the front, only the sides).
To make the side pieces, I had 28 inch wide material in a bolt. I think that was the size. Not far off if not quite right. I measured the highest part then cut 4 panels per fit to fit that. Then got up on a chair with a buddy and just wrapped it over the bars, and safetypinned it so the floor part was even. Took'em off and used iron on sewing tape for the seams and trimmed the excess. Did same for the 'doors' except didnt sewing-tape seam the panels together on the front.
Hey, I was a poor college student with imagination (grin). Looked down right spiffy when I got done!
Biggest problem (besides heat in winter) was outlets. Owner had electrician run a metal pipe pretty much in the edges of the eves with boxes standing up with outlets every 6ft or so on both sides, but that was only in my last 6 months there. It wasnt a big house so if memory serves, this attic room was something like 40ft long (maybe a bit more), and about 20 wide 'usable space' then the rest was too far in the eves. The flooring ran flush to the very outer edges which met the finished off drywall/wood rafters perfectly. I remember he had to upgrade the electrial system to be able to add this and it was multiple lines run through this 'runway' so it wasnt like he had it all on one circuit. I recall breakers labeled 'attic' and pretty sure there were 6 of them supporting 12 outlets. I moved out in summer but recall his plan was to be able to add electric heaters (oil filled electric radiators?) every 6ft offset from side to side (12 total) but he was gonna start with just 6 of them (3 per side) and see if that worked.
Oh, he also added a heavy duty outlet by the only window (side of house). I'd been using a box fan in the window with a stand rotating fan over the bed, but he added this to support a window AC unit which did come in while I was still there.
Why did I move? Had to. It was his son's place and he was returning from the Army to go to school and bringing a wife and baby (grin). No hard feelings. Me and my roomates found other digs, but never one as charming.
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cshenk wrote:

You were damn lucky there was never a fire there. I used to know somebody who lived a year in a similar setup, but at least she had stairs in a closet. To get to her area of attic, you had to walk past chimney stack. I installed a smoke alarm the next day, and visqueen and duct taped the rattly window to cut down the breezes. And we weren't even going out or anything- she was just a buddy's kid sister.
-- aem sends...
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"JayTKR" wrote

To bad. Had an aprtment once were the 3rd bedroom was a 'finished off' attic. The eaves made great storage. What we did was put up caffee curtin rods all along it and lots of pretty and simple gingham check. Insulated but didnt finish back there, yet made great storage.
Looked nicer than it sounds against the solid wood floors. Ceiling was insulated and drywall between the beams with a little molding to make the seams look nice, so you had about 1 inch of wood rafter showing.

Ower used cloth tacked up to keep any insulation dust in. More wasnt needed and might have created a problem.
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"JayTKR" wrote

To bad. Had an aprtment once were the 3rd bedroom was a 'finished off' attic. The eaves made great storage. What we did was put up caffee curtin rods all along it and lots of pretty and simple gingham check. Insulated but didnt finish back there, yet made great storage.
Looked nicer than it sounds against the solid wood floors. Ceiling was insulated and drywall between the beams with a little molding to make the seams look nice, so you had about 1 inch of wood rafter showing.

Ower used cloth tacked up to keep any insulation dust in. More wasnt needed and might have created a problem.
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"JayTKR" wrote

To bad. Had an aprtment once were the 3rd bedroom was a 'finished off' attic. The eaves made great storage. What we did was put up caffee curtin rods all along it and lots of pretty and simple gingham check. Insulated but didnt finish back there, yet made great storage.
Looked nicer than it sounds against the solid wood floors. Ceiling was insulated and drywall between the beams with a little molding to make the seams look nice, so you had about 1 inch of wood rafter showing.

Ower used cloth tacked up to keep any insulation dust in. More wasnt needed and might have created a problem.
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