Comments on: Joe Lstiburek’s Ideal Double-Stud Wall Design

By: Thomas A. Peterson

Thomas A. Peterson — Tue, 05 May 2015 20:37:46 +0000

David,

David,

Your questioning the construction sequence for the outer wall, is why I recommend a slightly different procedure.
1. Frame from foundation to roof.
2. Install exterior sheathing & DP
3. Exterior siding = weather tight shell.
4. Install insulation in exterior framed wall.
5. Continuous insulation board attached to interior of studs.
6. 6 mil vapor retarder next attached to floor decking and cap vapor retarder (bit more difficult on multistory). Significantly reduces air infiltration between and under all plates & studs.
7. Next build second lightly framed curtain wall (studs offset)to hold all electrical & any plumbing inside of continuous vapor retarder with more insulation then sheetrock+.

This system allows for easier framer understanding (no insulation blowing in the wind) and much easier quality control.

Like Dr. Joe's there is much more to this system.

By: Thomas A. Peterson

Thomas A. Peterson — Tue, 05 May 2015 16:37:46 +0000
David,   
David,     Your questioning the construction sequence for the outer wall, is why I recommend a slightly different procedure.  1. Frame from foundation to roof.  2. Install exterior sheathing & DP  3. Exterior siding = weather tight shell.  4. Install insulation in exterior framed wall.  5. Continuous insulation board attached to interior of studs.  6. 6 mil vapor retarder next attached to floor decking and cap vapor retarder (bit more difficult on multistory). Significantly reduces air infiltration between and under all plates & studs.  7. Next build second lightly framed curtain wall (studs offset)to hold all electrical & any plumbing inside of continuous vapor retarder with more insulation then sheetrock+.    This system allows for easier framer understanding (no insulation blowing in the wind) and much easier quality control.     Like Dr. Joe's there is much more to this system.

By: Foster

Foster — Fri, 01 May 2015 00:08:13 +0000
What's the construction
What's the construction sequence for the outer wall?

1. Frame from foundation to roof.
2. Install insulation
3. Hope it doesn't get windy or rainy.
4. Install exterior sheathing & WPABL.
5. Install exterior finish.

Is that it?

By: Foster

Foster — Thu, 30 Apr 2015 20:08:13 +0000
What's the construction
What's the construction sequence for the outer wall?    1. Frame from foundation to roof.  2. Install insulation  3. Hope it doesn't get windy or rainy.  4. Install exterior sheathing & WPABL.  5. Install exterior finish.    Is that it?

By: David Butler

David Butler — Thu, 30 Apr 2015 13:52:32 +0000
Seems to be some confusion in
Seems to be some confusion in the comments (and responses by AB).

First, I think Thomas D's link did a good job explaining the not-often used term double-wall as a non-insulated wall where outer sheathing also serves as the inside wall -- thus 'single wall'.

OTOH, by that definition, a double wall is what we think of as conventional stud wall -- with sheathing on outside and drywall (or whatever) on the inside, thus two surfaces or double wall.

That said, methinks building science terminology is confusing enough without imposing such a limited regional slant on everyone else.

As for Edgar's question, I believe he's asking why the insulation doesn't fall in the gap between the two walls. If so, then the correct answer is that the insulation is supposed to fill the in-between gap (see 2nd diagram).

Finally, after reading the previously referenced article, I saw nothing to lead me to think Joe endorsed that wall. And after the postscript you added relating Joe's phone call, no one else would have, either.

If Joe gave you a hard time for not spelling out a disclaimer on his behalf in your article, you should have told him to chill. I thought you did a fine job "reporting" on Kohta's report.

By: David Butler

David Butler — Thu, 30 Apr 2015 09:52:32 +0000
Seems to be some confusion in
Seems to be some confusion in the comments (and responses by AB).     First, I think Thomas D's link did a good job explaining the not-often used term double-wall as a non-insulated wall where outer sheathing also serves as the inside wall -- thus 'single wall'.     OTOH, by that definition, a double wall is what we think of as conventional stud wall -- with sheathing on outside and drywall (or whatever) on the inside, thus two surfaces or double wall.    That said, methinks building science terminology is confusing enough without imposing such a limited regional slant on everyone else.      As for Edgar's question, I believe he's asking why the insulation doesn't fall in the gap between the two walls. If so, then the correct answer is that the insulation is supposed to fill the in-between gap (see 2nd diagram).     Finally, after reading the previously referenced article, I saw nothing to lead me to think Joe endorsed that wall. And after the postscript you added relating Joe's phone call, no one else would have, either.     If Joe gave you a hard time for not spelling out a disclaimer on his behalf in your article, you should have told him to chill. I thought you did a fine job "reporting" on Kohta's report.

By: Tim Lacey

Tim Lacey — Thu, 30 Apr 2015 03:30:36 +0000
No mention that the moisture
No mention that the moisture meters may have been installed incorrectly and gave false readings. Just saying.

By: Tim Lacey

Tim Lacey — Wed, 29 Apr 2015 23:30:36 +0000
No mention that the moisture
No mention that the moisture meters may have been installed incorrectly and gave false readings. Just saying.

By: Allison Bailes

Allison Bailes — Wed, 29 Apr 2015 23:28:04 +0000
Mac S.:
Mac S.: Thank you, sir! I have to make it simple enough so I can understand it. Here's a direct link to the Galena page at the Cold Climate Housing Research Center:

Galena Prototype Home

Edgar: Unfortunately the BSC diagrams don't show the bottom of the wall details, but there would need to be OSB or plywood at the bottom, connecting the outer double-stud section to the bottom of the structural wall, maybe using a ledger.

By: Edgar

Edgar — Wed, 29 Apr 2015 22:13:06 +0000
Allison, what is holding the
Allison, what is holding the interior wall insulation from falling into the 4.5 inch air space?