Attic Insulation - Building & Construction - Page 2 - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

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

Reply
 
Thread Tools Search this Thread
Display Modes
Old 11-12-2009, 12:22 PM   #16
Member
 
Join Date: Oct 2009
Posts: 92
Rewards Points: 143
Default


no sealing yet. ARe you referring to sealing cracks and such with foam?
dorlando is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-12-2009, 01:16 PM   #17
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


"Question on installing batt over existing blown in. Do I want to go perpeindicular to the joists or still lay the bad between them? My blow in barely reaches the top of the 2x4 if that, it is only 3-4" deep." ----- If you lay batts with the bays, the R-value of a 2x4 is R-4.38. And your air space over the 2x4 to the top of the batt (8") is R-2 = R-6.38. Run them perpendicular to get full R-value everywhere.

With an 1-1/2" gap between each batt, in a 20' attic, added up would be 12" wide strip across the attic only insulated to R-6-1/2, with the rest at R-40.
Be safe, Gary
__________________
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-12-2009, 01:29 PM   #18
Member
 
Join Date: Nov 2008
Location: Michigan
Posts: 6,728
Rewards Points: 116
Default


Quote:
no sealing yet. ARe you referring to sealing cracks and such with foam?
Yes. I was surprised how many spots were letting warm air up into our attic. The hatch cover being uninsulated was letting a lot of warm air up there too.

Another spot I noticed was around the bathroom ceiling fan.

Just go through it with a fine-tooth comb and you might find lots of places to seal.
gma2rjc is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-12-2009, 09:02 PM   #19
Member
 
Join Date: Oct 2009
Posts: 92
Rewards Points: 143
Default


Looking online at owens corning they sell an R30 and R38 faced that they say you can use in the attic. I thought you weren't supposed to you faced in the attic? an engineer friend of mine said you can as long as the paper is facing up. any comments on that?
dorlando is offline   Reply With Quote
Old 11-12-2009, 09:16 PM   #20
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


Faced only in very cold climates, it goes towards the heated space:
"My home has about six inches of fiber glass insulation in the attic, and I'm planning to add more. Should I use faced insulation?
No. Use only unfaced fiber glass insulation with no vapor retarder. A facing acts as a vapor retarder, which helps reduce the amount of moisture entering a wall, ceiling, or floor. In heating climates, your original layer of insulation should already have a vapor retarder facing the "warm-in-winter" side (living area) of your home.
If you add a second vapor retarder with another layer of faced insulation, any moisture that does get through the first layer may condense on the second. This might cause water stains on the ceiling and could lead to severe structural damage. Install the second layer of unfaced insulation perpendicular to the first, covering the wood ceiling joists to reduce heat loss through the wood. (NOTE: Apply the second layer of insulation perpendicular to the first layer only when the joist cavity is full. Otherwise, apply the second layer right on top of the first layer, between the joists.)" From: http://saveenergy.owenscorningblog.c...questions.html
Be safe, Gary
__________________
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Old 11-13-2009, 05:11 AM   #21
Remodeling Contractor
 
Join Date: Dec 2008
Location: Sandy Hook, CT
Posts: 3,590
Rewards Points: 2,000
Default


(NOTE: Apply the second layer of insulation perpendicular to the first layer only when the joist cavity is full. Otherwise, apply the second layer right on top of the first layer, between the joists.)"

The OP mentioned the joists were not filled, this is why I said to lay the new insulation with the bays, but you added to go the other way..... I guess we need to be there?
Bob Mariani is offline   Reply With Quote
Old 11-13-2009, 10:10 AM   #22
Member
 
Join Date: Oct 2009
Posts: 92
Rewards Points: 143
Default


I apologize for confusion on the joists being filled or not. So, if I currently have blow in(looks part fiber glass and part cellulose) can I install a layer of unfaced and then a top layer of faced? In other words, can you install faced as long as it is the top layer? Where I live I can only unfaced in R30 and would like to add more than R30.

Thanks
dorlando is offline   Reply With Quote
Old 11-13-2009, 11:28 AM   #23
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


Bob, she said 2x4 joists in post #10, before you answered. I know you knew correctly but I didn't post until no one noticed your answer as I came on towards the end. (Probably before your coffee, I do that too.....)

Dorlando, "In other words, can you install faced as long as it is the top layer?" ----- NO. Only faced at the very bottom layer, under the blown-in. Reason: see middle of my post # 20......
"Where I live I can only unfaced in R30 and would like to add more than R30." ------ You are at 11-12" of R-value now or 98% of total, add more if you wish. http://www.anchorinsulation.com/pdfs...insulation.pdf Look up your energy requirements for your local area. Or spend the money on other more economic energy savers, sealing as mentioned by Gm.earlier, and foam board (also rebate) : See "Shallow rafter pitch and Fig, 1: http://www.homeenergy.org/archive/he...96/961110.html
Be safe, Gary
__________________
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Old 11-13-2009, 06:19 PM   #24
Member
 
Join Date: Oct 2009
Posts: 92
Rewards Points: 143
Default


What do you all think of radiant barriers applied to the underside of the sheathing? are they worth it and what kinds are the best to get?
dorlando is offline   Reply With Quote
Old 11-14-2009, 01:11 PM   #25
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


Help a lot in the sunny States. "On a sunny summer day, solar energy is absorbed by the roof, heating the roof sheathing and causing the underside of the sheathing and the roof framing to radiate heat downward toward the attic floor. When a radiant barrier is placed on the attic floor, much of the heat radiated from the hot roof is reflected back toward the roof. This makes the top surface of the insulation cooler than it would have been without a radiant barrier and thus reduces the amount of heat that moves through the insulation into the rooms below the ceiling." From: http://www.ornl.gov/sci/roofs+walls/radiant/index.html
Be safe, Gary
__________________
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Old 11-14-2009, 02:42 PM   #26
Member
 
Join Date: Oct 2009
Posts: 92
Rewards Points: 143
Default


I read a couple of other threads on here that the radiant barriers only provide a very small % of relief. I thought I also read somewhere that the savings is only $400 over a 25 year period.
dorlando is offline   Reply With Quote
Old 11-14-2009, 06:33 PM   #27
Remodeling Contractor
 
Join Date: Dec 2008
Location: Sandy Hook, CT
Posts: 3,590
Rewards Points: 2,000
Default


As just stated... it depends on where you are. In hot sunny locations savings will be significant. In Seattle it may be a waste of money.
Bob Mariani is offline   Reply With Quote
Old 11-15-2009, 06:43 AM   #28
Member
 
Join Date: Oct 2009
Posts: 92
Rewards Points: 143
Default


ok. Trick question maybe, if I blow in cellulose or fiber how do you sucessfully go back into the attic to lay the radiant down without disturbing the blow in? I'm assuming you don't want to be compacting down by stepping on it, etc.
dorlando is offline   Reply With Quote
Old 11-15-2009, 07:17 AM   #29
Remodeling Contractor
 
Join Date: Dec 2008
Location: Sandy Hook, CT
Posts: 3,590
Rewards Points: 2,000
Default


lay plywood walking planks down moving them as you work. The insulation will not stay compacted.
Bob Mariani is offline   Reply With Quote
Old 11-15-2009, 02:30 PM   #30
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


Quote:
Originally Posted by dorlando View Post
I read a couple of other threads on here that the radiant barriers only provide a very small % of relief. I thought I also read somewhere that the savings is only $400 over a 25 year period.
At the bottom of that article I gave you has another page discussing savings (in purple), here: http://www.ornl.gov/sci/roofs+walls/radiant/rb_02.html
Be safe, Gary
__________________
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Sponsored Links
Advertisement
 
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
Cape Cod Style House Attic/Crawl Space Insulation Help Danielg Insulation 24 05-21-2012 08:20 AM
Recently Topped Up Attic with Blown Insulation...Now I have Frost/Condensation earthad1 Building & Construction 81 02-18-2011 12:42 PM
Adding attic insulation pomelo Building & Construction 3 10-22-2009 05:19 PM
Insulation over Attic Walkway BigJimmy Building & Construction 4 06-23-2008 02:13 AM
attic insulation question dderolph Building & Construction 10 11-03-2007 05:21 PM




Top of Page | View New Posts