Sealing Around Air Baffles - Insulation - DIY Chatroom Home Improvement Forum
Advertisement


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 01-07-2016, 08:30 PM   #1
Member
 
Join Date: Feb 2015
Posts: 68
Rewards Points: 42
Default

Sealing around air baffles


I added air baffles to each rafter bay and all new insulation last year. I didn't have time to properly air seal around the baffles. They are straight baffles. They do not have the wrap around on the soffit side.

I am planning on installing a continuous vent soffit. Is it ok to use foam board (with spray foam around the edges) to seal around the baffles from below when I am replacing the soffit? Would the foam board be considered exposed in this location? Should I use a different material?
omgdiddy is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-07-2016, 09:06 PM   #2
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: Washington DC Metro Area (VA, MD, DC)
Posts: 26,108
Rewards Points: 1,022
Blog Entries: 41
Default


Why do you need to seal the baffles? Is this a vaulted ceiling? The top plate needs to be sealed and insulated.
Windows on Wash is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-07-2016, 11:26 PM   #3
Member
 
Join Date: Feb 2015
Posts: 68
Rewards Points: 42
Default


Just to clarify, I want to seal the large gap between the top plate of the wall and the bottom of the baffle.

The way it is now, some of the air is getting pulled under the baffle and through the insulation, making it dirty.

2 sides of the house have slanted ceilings, 2 have flat. They both have the same size gap to fill.

Thanks for the reply.
omgdiddy is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-08-2016, 08:22 AM   #4
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: Washington DC Metro Area (VA, MD, DC)
Posts: 26,108
Rewards Points: 1,022
Blog Entries: 41
Default


Spray foam will work as will a dense batting material. Roxul will do better than fiberglass as it is far less subject to wind washing.
Windows on Wash is offline   Reply With Quote
Old 01-08-2016, 08:44 AM   #5
Member
 
Join Date: Dec 2015
Location: North Shore, MA
Posts: 71
Rewards Points: 142
Default


Is this what you mean?

I don't have soffit vents, so in your case you wouldn't want to block the vent airflow, but those are the outside top-plates sealed with spray foam. A 30" foam gun will do wonders for those tight spaces.

Alketi is offline   Reply With Quote
Old 01-08-2016, 08:47 PM   #6
Member
 
Join Date: Feb 2015
Posts: 68
Rewards Points: 42
Default


Yes like that, but from below when I am changing out my soffits. Would it be possible to do something like that from below? Any ideas?
omgdiddy is offline   Reply With Quote
Old 01-08-2016, 11:31 PM   #7
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


Lol. Yes, air seal around it for better air-flow up and toward the roof deck. Some of that incoming air will fall anyway (the colder portion at least) and mix with the main area attic air creating convective loops, three of them, on top of and in the top few inches of your insulation when the temps get cold enough. Fiberglass, rock wool and cellulose are all fibrous air permeable insulation. You need a rigid plywood or foil-faced foam board with canned foam (fire code) around the baffles.

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 01-09-2016, 11:23 AM   #8
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: Washington DC Metro Area (VA, MD, DC)
Posts: 26,108
Rewards Points: 1,022
Blog Entries: 41
Default


How tall is the gap?

I have seen folks over apply foam in some of these cases and create issues by either letting the foam expand into the soffit (creates and unsightly mess) or over expand and crush the baffle (effectively limiting the ventilation).

Depending on the gap size, you would be well served to seal the top plate first, add in layers of rigid foam to close the gap, and then insulate with a low expansion (closed cell) foam to close the final gap and add R-Value.

It doesn't need to be airtight there if we are talking about a vented attic design, but the more R-Value the better.

This all works in a perfect world with proper access and ease of installation.

Roxul insulation is available in different densities. If you opted for the higher density batts, they are more resistant to air flow as compared to FG.
Windows on Wash is offline   Reply With Quote
Old 01-09-2016, 04:39 PM   #9
Registered User
 
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526
Default


I sure wouldn't use rock wool unless in a panel form (R-8) and even then you are installing from the outside, if I understand correctly- so it would insulate between outside air/attic air... waste of money. With your limited HAP, a rigid foam is best (from the inside over plate line), with the rigid (or plywood) air seal against the outside from the roof sheathing to the wall broken by the added chute vent. With a fibrous insulation touching the roof sheathing, it will rob you of heat from the room below by conduction. At least wrap any fibrous insulation in a plastic bag which also stops air and the moisture from depositing on the fibers degrading its R-value.
1. sealing around the baffles from the outside (which your post is about),
2 insulating/sealing on the inside- over the wall plate. Without the air-sealing on the outside, air will be drawn in through your fiberglass (as a furnace filter) leaving the dirt behind. Unless you block it off by layers of rigid on the plate and canned foam. Sealing around it also makes the attic draw from the baffles more, without a competing, easier air flow path.
Hopefully, the soffit supply vents are next to the fascia board, not in the mid span or near the house, for optimum air flow without moisture/snow due to air currents there. Also, air seal the attic, all top plate intersections of ceiling/wall drywall joints, any pipe/wiring holes, chases, drop ceilings, etc. with appropriate rated canned foam.

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?

Last edited by Gary in WA; 01-09-2016 at 04:44 PM. Reason: sp
Gary in WA is offline   Reply With Quote
Old 01-09-2016, 04:45 PM   #10
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: Washington DC Metro Area (VA, MD, DC)
Posts: 26,108
Rewards Points: 1,022
Blog Entries: 41
Default


How many baffles will you be retrofitting?

From the exterior makes it more manageable and expands your options to be certain.
Windows on Wash is offline   Reply With Quote
Old 01-11-2016, 12:53 AM   #11
Member
 
Join Date: Feb 2015
Posts: 68
Rewards Points: 42
Default


The baffles are up and everything has been air sealed except the exterior top plates. There are probably 50 or so if I had to guess. Not sure what the gap will even look like from below until I open it up. I'll take both of you guys' advice and put it toward my project. Hopefully I remember to take some pics so I can share what I learn. It could be a while though before I get around to it. Thanks for the replies.
omgdiddy is offline   Reply With Quote
Old 01-11-2016, 06:51 AM   #12
Exterior Construction
 
Windows on Wash's Avatar
 
Join Date: Aug 2011
Location: Washington DC Metro Area (VA, MD, DC)
Posts: 26,108
Rewards Points: 1,022
Blog Entries: 41
Default


Post up a pic once you open her up.
Windows on Wash 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
Need Baffles on Whole House Fan? katanna HVAC 8 05-15-2015 10:50 AM
Attic insulation quotes, to add baffles or not? CaptJackSparrow Insulation 4 03-04-2015 06:35 PM
Proper Vent Baffles: To be continuous or not? jcarlan Roofing/Siding 7 12-27-2011 08:56 PM
Air sealing attic mmastran Insulation 11 05-25-2011 07:31 AM
Insulation & Baffles Bruce50 Insulation 1 03-15-2011 08:49 PM




Top of Page | View New Posts