EcoRenovator  

Go Back   EcoRenovator > Introductions
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 12-01-11, 09:29 AM   #11
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

All the r-values you see should be age corrected ratings. Initial r-values shortly after installation may be higher for some materials. Same goes for cellulose that settles in attics.

__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 12-01-11, 10:20 AM   #12
scottorious
Helper EcoRenovator
 
Join Date: Nov 2011
Location: bloomington IL
Posts: 45
Thanks: 0
Thanked 1 Time in 1 Post
Default

is one brand of isoboard better than another?
scottorious is offline   Reply With Quote
Old 12-01-11, 10:35 AM   #13
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,525
Thanks: 1,162
Thanked 374 Times in 305 Posts
Default

Its really hard to say. If I see two r-values I normally just use the lower one to be on the safe side. If its actually higher, its just that much better.
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 12-01-11, 02:14 PM   #14
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,004
Thanks: 303
Thanked 723 Times in 534 Posts
Default

Quote:
Originally Posted by scottorious View Post
...I have thought about using the foam board up there. thats a very diy kind of project. what are the cons of layering foam board in the rafters?...
scottorious,

This is an approach that I have a good bit of experience with.

I decided to go this route because I wanted to get the most R-value in the least space. I have the same house configuration that you have.

When you work on your walls/ceiling, you will want to be mindful of two things:
  • Infiltration
  • Insulation

My first efforts were to use fiberglass and put it in the wall and then sheet rock over it. That method was better than no insulation at all, but it didn't get at infiltration, and because of this, the insulation in the wall was not as effective as it could have been. Also, the insulation I put in at the time was rated to be R-13, not so high, and the flow of air through the wall degraded that R-value considerably.

My second effort was to fill the wall cavity recycled shipping peanuts, because it was free, and testing showed it to be on par with fiberglass. Subsequent testing on a plastic peanut/pearlite mix proved much better, because the pearlite filled in voids in the peanuts, and yielded an R-value that was higher than cellulose. I used this combined method on one side of the house and it worked well, but not as well as subsequent methods...

My third effort was to use recycled insulation board chunks in the wall, but I didn't seal between layers or pieces, so the efforts were little better than nothing.

My forth effort was to use new rigid foam board (expnaded ploy-styrene, AKA: EPS), carefully cut exactly to size and layered in the wall until the cavity was filled 100%. This worked so well that I was shocked at the difference between this method and all previous methods. The difference was that I had completely eliminated all air movement in the wall (infiltration), along with using an R-4 to 4.5 insulation. Using this method, I was actually getting minimum R16 in the walls, instead of using fiberglass reated at R-13 in an unsealed cavity and having that R-value degraded to some unknown value that was significantly less than R-13, by air flow through the wall.

I was so impressed with this method that I thickened the walls and roof an extra two inches to recieve another 2" layer of EPS, in the walls and ceiling.

I am continuing to work with this method, with the exception that instead of cutting exactly to fit, I now cut 1/4" all around and run a bead of canned foam in the 1/4" gap to seal it. This has proven to be easier than cutting exactly to shape, and makes a better seal at the edges. Care must be taken to not allow the canned foam to get behind the EPS, because it will expand and push the EPS out.

When I was selecting foam board to use, I had the following choices:
Expanded Polystrene (EPS) - (R-4 to 4.5 per inch)
Extruded Polystyrene Board (XPS) - (R- 5 per inch)
Polyisocyanurate Board - (R-6.5 per inch)

In making my selection, I tried to weigh cost vs. R-value and decided on EPS. Subsequently, I have read about the possibility of degraded R-value in Polyisocyanurate, due to the gradual absorption of moisture. Here is a link on that issue, you should do further research.

Also the cost of energy has gone up since I started the project, I might lean more towards XPS now, especially important in the ceiling.

Another issue for you to consider is that using this insulation method will radically reduce the infiltration of air into your house, and you will require mechanical ventilation in the winter, I would recommend some kind of heat exchange ventilator (AKA: HRV). The mechanical ventilation will be required both for humidity control and also for air quality.

Also, for this method to be completely effective, you need to concentrate on the junction where the roof-slope meets the wall, and make sure that this area is totally sealed. Same goes at the details around the foundatoin and the junction where floors meet walls.

This method is not easy or cheap, but given that you are working on an older house, it is amazingly effective.

Regards,

-AC_Hacker

__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Reply


Thread Tools
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

Forum Jump


All times are GMT -5. The time now is 06:07 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design