Replies

1. 
   Clewless1 | Nov 23, 2009 02:13am | #1

   Air tight drywall is that ... air tight ... not nec. a vapor retarder approach. You either include poly as part of that approach or install a different vapor retarder (e.g. paint). Many air tight drywall approaches, I think, install the ceiling drywall before the interior partitions go up. You also caulk any exposed edges of drywall ... e.g. the bottom edge near the floor.

1. 
   fingersandtoes | Nov 23, 2009 02:27am | #2

   I'm not sure I follow you. If you include a poly vb then surely you aren't using an airtight drywall approach.

   Putting up the interior partitions after drywall would make plumbing,and electrical rough-in a nightmare. What if they are loadbearing?

   I know it is a common strategy. Many posters say they no longer use a poly vb. I'm just wondering how they effectively limit air infiltration into the walls and ceiling. 

1. 
   Clewless1 | Nov 23, 2009 08:01am | #8

   Not sure about the poly. No reason why it would compromise the air tight aspect of the construction. Putting up the ceiling makes plumbing/wiring access more difficult, but other than that ( :) ) it's 'no big deal' ... you drill up through the top plates to get stuff into the ceiling. Not sure about load bearing walls. It's been a long time since I understood the details of air tight drywall so I'm missing a lot of details here.

1. 
   DanH | Nov 23, 2009 03:37pm | #11

   Of course, in drilling through the top plate and ceiling rock you create a hole in the air barrier, kind of negating the reason for putting up the rock first.
   A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter

1. 
   Clewless1 | Nov 23, 2009 04:28pm | #12

   Actually no, it doesn't negate it as part of air tight drywall/construction is dealing w/ the air that migrates into interior walls and up into the attic through the cracks in the construction ... e.g. between the drywall and the framing. When you drill through the top plate, you foam/seal the hole, but you still have continuous air barrier across the rest of the framing.

2. 
   DanH | Nov 23, 2009 04:30pm | #13

   But either way you've got to do extra sealing. I don't know why folks don't just do what I did and paint the tops of the walls with some sort of glop after the wiring and plumbing is in.
   A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter

3. 
   Clewless1 | Nov 23, 2009 04:39pm | #14

   Pay your money ... take your choice as I always say. It's like the 1st and 2nd law of thermo. Generally a plus in one aspect is a minus in another. Whatever works.

2. 
   DanH | Nov 23, 2009 03:52am | #3

   Foil-backed drywall has been used in place of the VB.
   A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter

1. 
   Clewless1 | Nov 23, 2009 07:58am | #7

   So has VB paint. Not hard to get ... not too special, either.

1. 
   DanH | Nov 23, 2009 03:35pm | #10

   Yeah, but the foil-backed drywall eliminates the need to wear a tinfoil hat.
   A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter

2. 
   LIVEONSAWDUST | Nov 23, 2009 04:20am | #4

   I'm not sure that it meets the "airtight " definition, but on recent houses we are

   building (energy star certified), we are foaming the top plate/drywall junction. Its not

   difficult or too time consuming. Its also important to seal any holes in plates as well

   as ceiling mounted electrical boxes, exhaust fans etc.

   I've considered having the drywall subs seal the drywall to the top plate with the

   newer spray foam adhesive that you can use in place of subfloor adhesive, but

   worried about quality control with this method

1. 
   DanH | Nov 23, 2009 05:11am | #6

   What I did in our house (1976 vintage) is to paint the tops of the studwalls with roof coating -- the stuff that goes on like thick paint and hardens to rubber. You can pour it on fairly thick and brush it around a bit to seal all the gaps, and you get a good seal quickly.
   A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter

3. 
   HuskiesHowls | Nov 23, 2009 04:22am | #5

   I'm working on my own house, and I've found that yes, its time-consuming. Its a lot of little nitpicky stuff that seems to go on forever, whether its rainscreen, or air-tight drywall, or just flashing a window properly.

   Here's a link to a website where a house is built from the ground up using all these principles, and the guy was very good about taking a lot of pictures and documenting things. The air-tight drywall starts about picture 72.
   http://www.imageevent.com/okoboji_images/deloreshouse

   Dick

   A joyous greeting from the furkids---the best time of the day
4. 
   shelternerd | Nov 23, 2009 08:15am | #9

   We used airtight drywall approach for many years and I wrote about it with pictures here http://www.chandlerdesignbuild.com/indexFull.php?id=vidraMoody&t=The%20Vidra-Moody%20Residence scroll down towards the bottom and you'll see what I'm talking about.

   Bascally you run a strip of Tyvek or poly between the sill seal / termite flashing and the mud sill and then tape it to the exterior house wrap and run another between the top plate and the upper top plate and tape that to the exterior tyvek as well, Then you caulk all the interior and exterior top plate penetrations and when the sheet rock hangars are done hanging the ceilings you run around and staple up little 1" strips of sill seal to the top plate so when they hang their wall drywall it will fit tightly to the top plate rather than the normal drafty crack that you have there.

   In this house we stapled up the sill seal strips before the ceiling drywall was hung and just ran around and fixed the places that got damaged when they hung the ceilings. The way we cut the strips is we make a slitting jig with an 18" chunk of 2x6 with a couple of 16D nails tacked ialong the edges and four brand new utility knife blades tapped into the end of it at an angle. You get the sill seal feeding it between the nails along the 2x6 and push it through the blades making four cuts (six strips). Once you have a foot or so you just pull it throughand feed it into a clean trash can as you go and you can make several hundred feet of foam tape very quickly and cheaply. grab a slap tacker and a short ladder and you should be able to seal up a house in a couple of hours.

   ------------------

   "You cannot work hard enough to make up for a sloppy estimate."

1. 
   Snort | Nov 23, 2009 09:47pm | #15

   Michael, how do you deal with piers and a tented crawl?http://www.tvwsolar.com

   We'll have a kid

   Or maybe we'll rent one

   He's got to be straight

   We don't want a bent one

   He'll drink his baby brew

   From a big brass cup

   Someday he may be president

   If things loosen up

1. 
   shelternerd | Nov 24, 2009 05:15am | #16

   Just6 pull the poly up the pier and wrap it well with Tyvek tape to hold it on with a little great stuff against the concrete to make a seal.------------------

   "You cannot work hard enough to make up for a sloppy estimate."

5. 
   Billy | Nov 24, 2009 06:15am | #17

   For airtight drywall try the following "BG32" gaskets from RCT.  Hammer tack them in place on the sides of the plates and elsewhere before the drywall hangers do their thing.

   They have some cool sill and rim joist gaskets and wall plate gaskets, too, and they're not too expensive.

   http://www.conservationtechnology.com/building_gaskets.html

   Billy

1. 
   fingersandtoes | Nov 24, 2009 06:36am | #18

   Thanks for all the information, I especially appreciate the links.