Replies

1. 
   AndyElman | Apr 05, 1999 07:08am | #1

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   Perhaps I should add the house is in NY, the Hudson Valley, just south of Poughkeepsie and north of NYC. --Andy

2. 
   Guest_ | Apr 05, 1999 08:00am | #2

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   fiberglass unfaced, 1 inch metal foil backed foam sheeting over rafters, tape the seams, and drywall all. Try not to recess any lights or electric boxes. No poly needed with the taped foam.

   Quick, easy, inexpensive, and pretty high R-value.

   You could also just drywall it all and blow in dense pack Cellulose with no roof venting left...Fred L is the guy to ask more about this.

   Near the stream,

   J

1. 
   Guest_ | Apr 05, 1999 06:14pm | #3

   *I especially agree about the no recessed lights. I have seen skylites placed low enough in steep roofs to be used for a view. I loved the idea but haven't used it myself yet. You didn't say hoe deep the rafters were, but I would go with the foam even with the cellulose insulation. Also I would insulate before building the knee walls.

3. 
   AndyElman | Apr 09, 1999 07:15am | #4

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   The rafters are 6 inch so I think that fg batts and foil faced sheets should give enough insulation. Is it worth putting vent channels under the sheathing behind the fiberglas? I could vent the soffit without much trouble. My biggest fear is having the roof rot out over my head. Well not the biggest, but it's close...

4. 
   Guest_ | Apr 09, 1999 09:06am | #5

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   Hi Andy,

   I'm no expert, but I have read all the arguments here and done a bunch of research on my own. And since the experts (except Jack) are avoiding it I'll tell you what I think.

   You don't want moisture coming into your walls (or roof) from the outside.

   You also don't want moisture coming into your walls (or roof) from the inside.

   If moisture does happen to penetrate that space you want a good buffer to absorb it.

   Control moisture from the outside with proper roofing techniques, painting and flashing. Control moisture from the inside by sealing drywall (hence the no recessed lighting issue), with proper mechanical setup and with adequate vent fans. It seems that dense pack cellulose absorbs errant moisture (wicking it away from framing) better than fiberglass.

   You don't vent walls. In your scenario your roof is basicly going to be a wall. Why vent it? I'd say seal the ridge vent. Make sure your roof doesn't leak any where. Jack seems intent on those foil backed foam sheets, I've never used them but am curious as to whether they'd trap moisture as opposed to distributing it as DP would do (this in the event of a leaky roof), thus rotting the framing.

   I've gotta say though, anything that's 4'x8' and I can lift with my teeth, I like already!

   Feel free Gabe, Fred , Gene, Blue and others to let me know where I'm off base.

   As for Jack (Lakeside), I too am Lakeside. Have you ever built a floating dock? I'm considering an addition to my puny one to accomodate a BBQ pit and a few Tiki Torches...

   Dan

1. 
   Guest_ | Apr 09, 1999 06:45pm | #6

   *Dan,Lakeside Dock Builders (Adirondocks, Call the Dock)Indeed I have built many O dock.The comercial floats are nice but pricey,...blue barrels can be picked up close to free, $10~Floating docks built with an ell shape rock less...my main beef with them.J

1. 
   Guest_ | Apr 09, 1999 07:16pm | #7

   *Thanks buddy, Blue barrels it is. I think I might go with a T-shape.

1. 
   Guest_ | Apr 14, 1999 05:58pm | #8

   *Hey Jack, can I put that foil backed foam board directly on my exposed purlins and then fill with cells or does it ruin the foil effect?

1. 
   Guest_ | Apr 14, 1999 09:18pm | #9

   *The foil needs an air space on at least one side to be a radiant barrier. You could place it with the foil facing the heated space and strap it with 1-by before hanging the drywall.

2. 
   Guest_ | Apr 14, 1999 09:29pm | #10

   *Dan. In the 3rd paragraph of your post you say "...and with adequate vent fans." In the 4th paragraph you ask "...Why vent it? I'd say seal the ridge vent." Am I seeing a contradiction that does not exist? GeneL.

3. 
   Guest_ | Apr 15, 1999 05:31am | #11

   *I think so Gene, I meant adequate bathroom and kitchen exhaust fans...Other than my semantics, am I right?or amarillo?Dan

5. 
   Craftsmen_ | Apr 26, 1999 08:42pm | #12

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   I am planning to add a room on my home, 16 x 20. the crawl space will be approx 2 feet off the ground, should I worry about a vapour barrier, is moisture going to be a problem, I live in Edmonton, Alberta, Canada.

6. 
   Guest_ | Apr 26, 1999 10:26pm | #13

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   Yes Craftsmen,

   even in the dry cold Edmonton region. A vapour barrier is your cheapest and most useful component.

   Like the Fram filter guy says, "You can pay me now or you can pay me later".

   Later is a lot more expensive.

   Gabe

1. 
   Guest_ | Apr 27, 1999 02:26am | #14

   *Craftsmen,Are you asking about a vapor barrier for the ground in the crawlspace or a vapor barrier within the walls?Steve

7. 
   Craftsmen_ | Apr 27, 1999 08:03pm | #15

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   I was inquiring about a vapor barrier for the ground in the crawl space, to prevent moisture from the ground entering the addition.

8. 
   Guest_ | Apr 28, 1999 02:31am | #16

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   Craftsman,

   I'm pretty sure that everyone here is in agreement that you should have some sort of impermeable barrier over the bare earth in your crawl space. It seems the disagreement stems from whether to vent or not. There are some compelling arguments against venting, and a whole lot of history for venting. Codes want you to do it, but also provide exceptions. Sec 409.1 in the Cabo book (1995).

   But yes, do cover that bare ground. And it's a lot easier to do it prior to framing and sheathing the floor above it...unless of course you have a rookie that needs to be picked on.

   For what it's worth,

   Dan

9. 
   Craftsmen_ | Apr 30, 1999 08:45am | #17

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   Thanks for the reply, what is normaly used? I was going to use 6 mil poly. How tight do the make the connection of poly to the perimeters.

10. 
    AndyElman | May 01, 1999 02:46am | #18

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    I am going to be turning an unheated attic space in my cape into a finished closet storage area. At the moment it is just rafters and sheathing overhead. I want to insulate, add sheetrock and skylites, but want to know if A: should there be a vapor barrior, B: should it go between just behind the sheet rock and over the rafters, C: the ridge is vented but the soffit is not. How much trouble will this cause me later? The space is over the kitchen and abutting the garage (unheated). Any suggestions? Thanks --Andy

11. 
    Guest_ | May 01, 1999 02:46am | #19

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    Craftsmen,

    Cross-laminated Poly is better. It's tougher and will last longer. It's commonly used with concrete installations, so look for it at a masonry supply place. Tu-Tuff is one brand, I forget the other major one.

    The main thing is to cover the poly with stone to keep it in full contact with the ground. Tape the seams. Poly left floating without sand or stone on top will be far less effective at stopping moisture should punctures develop (and they will).If your foundation walls are smooth, run the poly up them a couple of feet and seal with whatever you prefer for poly to masonry.

    Have fun,

    Steve