baffle and insulation/wind blocker for soffit


  #1  
Old 02-08-11, 08:49 AM
T
Member
Thread Starter
Join Date: Feb 2010
Location: USA
Posts: 15
Upvotes: 0
Received 0 Upvotes on 0 Posts
baffle and insulation/wind blocker for soffit

When I bought my house, the home inspector pointed out that my soffits were covered up with insulation and they needed baffles to provide an air channel. I was hiring a general contractor to handle some other minor repairs and corrections, so I also had him do this. The inspector made it found straightforward, so I trusted that the contractor would know what to do. As usual, I discovered that when you aren't explicit (i.e. a pain in the butt), you shouldn't expect anything to be done correctly.

Turns out, he just bought some plastic baffles from homedepot, pulled back the insulation, shoved them in, and put the insulation back. They are only held in by friction between the roof sheathing and the insulation batts. Its been almost 2 years since this was done, and I'm only noticing it now because I was thinking about upgrading my insulation with blown in.

1.) He didn't use any staples to secure the baffles. Some of them have been slid so far in that they are up against the fascia, which kind of defeats the purpose and closes off the air channel.

2.) There is no vertical barrier between the baffle and the wall plate to prevent insulation from getting into the soffit, or wind and moisture from getting into the insulation. Practically, this would be more of a problem if I had loose fill insulation, but I have done some research and it seems that new codes require such a barrier.

3.) The plastic baffle doesn't have anything to support the structure in the middle, so there are many places where the insulation has crushed the plastic up against the underside of the roof when it was moved back in place.

So I think I am going to give this a shot myself. Plastic baffles are relatively cheap, so I'm not opposed to buying new baffles that have an integrated insulation dam and wind blocker.

2 examples of this are:

Durovent
Accuvent

However, I have a concern about installing these. I went up in the attic and crawled into the eaves to get a closer look at what I'm dealing with. I was able to find this illustration which shows how my ceiling joists, roof rafters, and wall plate are put together.



It looks like I may have a problem installing a baffle with an integrated dam because the ceiling joist abuts next to the rafter instead of being exactly inline with it. The result is that any barrier or dam that I install on top of the wall plate will need to have a notch cut out for the ceiling joist. I suppose I could try to get the dam between the ceiling joist and the soffit instead (i.e. over the far edge of the wall plate), but I don't know if I can reach that far, given that my roof pitch is roughly ~5/12.

Another option, is to keep the existing baffles (or get better ones with some kind of center support to keep them from being crushed), staple them in correctly, and use these as a dam. It might be easier to install these from the outside (i.e. soffit) so that they are in between the ceiling joist and the soffit. I'd hire someone to do that though because I wouldn't be comfortable fumbling around with this while standing on a 20 ft ladder.

Any suggestions?
 
  #2  
Old 02-09-11, 10:37 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 9,460
Received 47 Upvotes on 43 Posts
Hi Thomase, sounds like you understand the purpose, more so than the contractor you hired. One of the new codes, which probably doesn't apply to you, although is is a good idea, tries to get the insulation to cover the top of the top plate rather than stopping at the inside edge. Since you sound like you want a good job, note, when we look at inside walls with an infrared camera, that top plate area is always cold. Wood instead of insulation and rarely covered on the outside or over the top. You can see where the Accuvent above is trying to reach out to cover the top, but it does not cover anything on the outside. I haven't seen any products that do, but if someone pulls your soffits to do an installation from the outside, it might be possible to come up with a solution. Mine was a piece of mineral wool cut to fit. Mineral wool is dense enough to block air flow. How you fill that space is somewhat dependent upon your construction, but often just some folded insulation tucked up in there will do the trick, but not fiberglass as it does poorly at blocking air. I also added a piece of 2x4" on edge the full length of the house as a ledge for that outside insulation.

When you stumble across a worker who ALWAYS does the job better than you expect, without you having to watch, hang on to them .

Bud
 
  #3  
Old 02-09-11, 09:21 PM
T
Member
Thread Starter
Join Date: Feb 2010
Location: USA
Posts: 15
Upvotes: 0
Received 0 Upvotes on 0 Posts
I got a sample of the accuvent from the manufacturer. The bottom part is very flexible and i think the idea is to cover the top plate and allow insulation over it, without exposing said insulation to the outside air.

However, since my pitch is so low there are only a few inches between the top plate and the sheathing and the vent itself will reduce that space even more.

No matter what I use, its going to be very difficult to get in there with a stapler. The accuvent is supposed to be stapled to the top plate. Even if I can reach it, how can I use a gun or have enough room to swing a hammer stapler at the correct angle? I've never used a hammer style stapler. Do you need to swing it hard?

Maybe it would be best to use a traditional baffle, and staple further up the sheathing where it is easier to get to. This way it won't slide up or down. Then the bottom part over the top plate can be held In place by friction with a piece of mineral wool like you suggest.

I guess I need to play around with the accuvent sample and see if there is a way that I can install it. I'd like to use blown in insulation and think I will need a rigid barrier like this to keep insulation out of the soffit.

Are there any tricks to working in tight spaces?
 
  #4  
Old 02-10-11, 04:43 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 9,460
Received 47 Upvotes on 43 Posts
Securing a baffle out where you can reach it and then installing some batt insulation down over the top plate should work fine. When you have a low slope and notched rafters there just isn't a lot of room down there. You won't want to compress the mineral wool or any other batt insulation, but once you determine the size/shape you can pre-cut them and detail their placement as needed.

The blown in insulation and the batt at the top plate will hold the baffle up in place and some staples will keep it from sliding out into the rafters.

Yes, a hammer style requires a good swing. I like to use an electric stapler for tight places. Just hold it firm against your work and pull the trigger. Not that expensive and available at most stores.

Bud
 
  #5  
Old 02-15-11, 07:59 AM
L
Member
Join Date: Oct 2004
Location: PA
Posts: 2,223
Received 8 Upvotes on 8 Posts
this may or may not apply to your circumstance but i tested out something in a hard to reach place..i bought a 1x3x8 or something very small like that, and stapled the baffle to it then attached the wood to the roof...it kind of looked like an inverted popsicle.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: