Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-24-2012, 11:45 PM   #1
Member
 
Join Date: Feb 2012
Location: Woodstock, IL
Posts: 118
Share |
Default

layered polyiso


Hello,

I am just about finished residing my house (going on 2 years now...). Under the siding on top of the sheathing, I covered the exterior with 1.5" Thermax polyiso.

I'm now finding out I was 1 sheet short. I can't find it ANYWHERE now (within a reasonable distance). In fact I can't find any brand foil-faced in 1.5".

My question is, can I layer .5" and 1" John Mansville foil faced polyiso without any ill effect? What if I peel the foil off of one back and one front, would that be needed? The seams are all taped of course.

Thanks.

__________________
Flooring Installer. Ecological Restoration Technician. Green Building Enthusiast. Obsessed with insulating and air sealing.
wewantutopia is offline   Reply With Quote
Old 08-25-2012, 12:20 AM   #2
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Default

layered polyiso


That will work, long as you have the housewrap in there (preferably under the foam board), and the air gap or rainscreen with any wood siding; Fig. 24, page 46; http://www.buildingscience.com/docum...-climate-zones

Don't bother pulling any foil facing as the inside foil face (alone) next to the sheathing will vapor (barrier) seal the wall there, be sure no inside vapor barrier. Without a strapping air gap- the outside foil is nil- unless using vinyl siding; http://energyguild.hubpages.com/hub/...lp-Save-Energy

Pictures, we love pictures!

Gary

__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Old 08-25-2012, 08:02 AM   #3
Member
 
Join Date: Feb 2012
Location: Woodstock, IL
Posts: 118
Default

layered polyiso


Quote:
Originally Posted by GBR in WA View Post
That will work, long as you have the housewrap in there (preferably under the foam board), and the air gap or rainscreen with any wood siding; Fig. 24, page 46; http://www.buildingscience.com/docum...-climate-zones

Don't bother pulling any foil facing as the inside foil face (alone) next to the sheathing will vapor (barrier) seal the wall there, be sure no inside vapor barrier. Without a strapping air gap- the outside foil is nil- unless using vinyl siding; http://energyguild.hubpages.com/hub/...lp-Save-Energy

Pictures, we love pictures!

Gary
I was mainly worried about water getting trapped between the 2 sheets. I guess that, since polyiso can absorb water, it is good thing to leave the foil on to protect the boards.

I do have housewrap between the sheathing and the foam. On top of the foam I have a "rainscreen"; I'm doing vinyl. I don't trust the adhesive on the tape to last for 20+ years (the life of the siding). I didn't want to lose the radiant barrier properties by covering the foil so... I got 1200 sq. ft. of emergency blankets (http://en.wikipedia.org/wiki/Space_blanket) for $35 and used them; lapping them properly of course.

Most of our 100 year old house now has 3" polyiso in between the studs that was foamed on all 4 sides so I'm not too worried about vapor migration.

The 2x4 wall assemblies now are ~R30 with ~10 of that being an exterior thermal break. I'm pretty psyched!

This spring I also covered the foundation to below the slab with 1.5" XPS.

Here's some pix:

This house was a foreclosure that the previous owners tried to flip and ran out of $. The did some REALLY bad work. For example: The replaced the windows (except the basement, I did that) with "standard" sized windows. The resulting gaps were just covered with OSB and painted to match the asbestos siding.

Before:






Foundation Before:


After new windows, fixing the mortar joints, repairing some of the crumbling concrete, parging, and 6 coats of liquid rubber foundation coating:



Foamed:


Finished. 6 More coats liquid rubber coating on the foam with sand added for texture:


Here is the last wall. Part of this project includes all new electric service, replacing the original meter and wiring. The new location for the meter is to the right of the picture (out of view), but that is what the 2x6s are running along the roof to near the peak.







Thanks for your help!!
__________________
Flooring Installer. Ecological Restoration Technician. Green Building Enthusiast. Obsessed with insulating and air sealing.
wewantutopia is offline   Reply With Quote
The Following 2 Users Say Thank You to wewantutopia For This Useful Post:
Gary in WA (08-27-2012), operagost (08-29-2012)
Old 08-26-2012, 11:23 AM   #4
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: VA, MD, DC
Posts: 5,700
Default

layered polyiso


Cool project.

Congrats to you for doing your research and doing it right.
Windows on Wash is offline   Reply With Quote
Old 08-26-2012, 06:29 PM   #5
Member
 
Join Date: Feb 2012
Location: Woodstock, IL
Posts: 118
Default

layered polyiso


Hey thanks! It's a totally different house already, but there is still LOTS to do!
__________________
Flooring Installer. Ecological Restoration Technician. Green Building Enthusiast. Obsessed with insulating and air sealing.
wewantutopia is offline   Reply With Quote
Old 08-26-2012, 10:30 PM   #6
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: VA, MD, DC
Posts: 5,700
Default

layered polyiso


Quote:
Originally Posted by wewantutopia View Post
Hey thanks! It's a totally different house already, but there is still LOTS to do!
There always is.

Ed Harris doesn't talk about that in those BS home ownership ads does he....

Windows on Wash is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Manufacture History Roofmaster417 Roofing/Siding 6 02-23-2012 02:40 AM
Fascia along gable layered like shingles? pldobs Roofing/Siding 10 10-10-2011 11:35 PM
Housewrap/Drainage Plane Behind Fiberfaced Polyiso or in Front? cloves Building & Construction 5 06-29-2011 12:51 AM
How do I *not* mangle polyiso panels when I pull vinyl siding for insulation blow? steveel Building & Construction 5 10-10-2010 09:02 PM
insulating heated garage(retrofit)- insul. & pipes KatieAK Building & Construction 0 10-25-2009 09:03 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.