# Rafter vents & insulation question



## Ed the Roofer (Jan 27, 2007)

3/8" staples with a hand squeeze staple gun, like those from Arrow Manufacturing, sold at Home Depot would be sufficient to hold the light weight material in place.

Do not overlap them, as they need interval spaces of about 1/2" to allow for any minute condensation build up to not accumulate to a waterfall like scenario when it graduates to the lower proper vents over the soffits, if you are installing them the entire length of the rafters.

Ed


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## k.kuenn (Oct 29, 2007)

Thanks Ed! Very helpful. I will keep them spaced by a 1/2 inch. Didn't know that.

Any idea what the black stuff may be? I'm worried someone may say "mold"...


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## Scuba_Dave (Jan 16, 2009)

Ed the Roofer said:


> Do not overlap them, as they need interval spaces of about 1/2" to allow for any minute condensation build up to not accumulate to a waterfall like scenario when it graduates to the lower proper vents over the soffits, if you are installing them the entire length of the rafters.
> 
> Ed


Now you tell me :laughing:
I was thinking you would want any water to drain down to the soffits
At least the addition rafter venst will be installed properly
Do you have a pic of the black stuff?
If its anything like what I have seen its just years & years of dust/dirt


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## k.kuenn (Oct 29, 2007)

I'll take a picture tonight when I'm there and send it to you later. Thanks.


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## Ed the Roofer (Jan 27, 2007)

k.kuenn said:


> Thanks Ed! Very helpful. I will keep them spaced by a 1/2 inch. Didn't know that.
> 
> Any idea what the black stuff may be? I'm worried someone may say "mold"...


It may be the beginning growth of Black Mold.

Air-flow and reduced humidity will stifle it's growth.

More Info:
http://www.epa.gov/mold/moldresources.html

Ed


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## Ed the Roofer (Jan 27, 2007)

Scuba_Dave said:


> Now you tell me :laughing:


 
You didn't ask.....

There should be instructions from each of the products manufacturers.

I installed it incorrectly on multiple occassions before I became aware of that precaution and have not heard back from anyone regarding any negative consequences, so it is probably a very minor issue, but still an issue that should be done correctly.

Ed


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## Scuba_Dave (Jan 16, 2009)

I guess I need to read more, makes sense



> 1. Install RAFT-R-MATE in each rafter
> cavity beginning at the soffit area, to
> assure the vent remains open, and
> continue up the cavity to the ridge vent
> ...


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## Ed the Roofer (Jan 27, 2007)

Wow!!! A 2" gap? I don't recall it having to be that large, but as long as the insulation does not peek through and restrict the air-flow, I see that it really wouldn't matter.

The reasoning that I read some time ago, was that a slight amount of humidity will condense enough to just form little droplettes, but, if you allow all of them to accumulate and flow uresticted bonding together, then you have created a cascading water-fall at the bottom of the Proper Vents, aka, Insulation Baffle Vents.

Ed


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## Gary in WA (Mar 11, 2009)

Actually Ed, You did tell Dave, 4 months ago! http://www.diychatroom.com/f9/attic-ventilation-channels-skylights-39911/

Problem is, Dave didn't read it......... BUT it was 18 days later to Dave's post!! So we'll let it slide, Dave. chuckle.

Be safe, G


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## Scuba_Dave (Jan 16, 2009)

Ah, I think I caught the end of that thread
I usually do make notes when I see something like that
I guess I have to let Ed off the hook too :wink:


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## Gary in WA (Mar 11, 2009)

Don't feel bad, Dave, here is one I learned today. I knew face stapling insulation is better than side stapling, as you don't compress it. That was what I answered in that poll a while ago. Even the manufacturer says- either way or use tension fit insulation batts. Well, I was looking for support showing Kraft paper on batts will allow some water vapor to move through, which it will, and I found this- too. [502.1.4.6] Inset Stapling Faced Batts is not Allowed. If faced batts are
used (kraft paper or foil facing material) and if they have a
stapling tab, they must be stapled directly to the face of the
stud. Stapling to the side of the stud compresses the insulation
and creates a *convective air channel* that reduces the
effectiveness of the insulation (see Figure 4-3).

Makes sense to me. Be safe, G


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## Ed the Roofer (Jan 27, 2007)

GBAR in WA said:


> Actually Ed, You did tell Dave, 4 months ago! http://www.diychatroom.com/f9/attic-ventilation-channels-skylights-39911/
> 
> Problem is, Dave didn't read it......... BUT it was 18 days later to Dave's post!! So we'll let it slide, Dave. chuckle.
> 
> Be safe, G





Scuba_Dave said:


> Ah, I think I caught the end of that thread
> I usually do make notes when I see something like that
> I guess I have to let Ed off the hook too :wink:


Thanks for making me laugh guys. :laughing:

Ed


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## k.kuenn (Oct 29, 2007)

Okay, here are the pics of the black stuff. Thoughts?

and, one last question....

What is your recommendation for insulating the ceiling in our finished attic.....faced or unfaced insulation? The guy at Lowe's sent us unfaced, but I was expecting faced so that I could staple it up. Currently, I don't have a ceiling up, yet in the living space. So I'm not sure whether I just didn't understand that I'd have to put the insulation up after the ceiling???


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## Barry J (Nov 21, 2008)

I thought these vents mount in between the rafters??
I don't get where the two inch spacing comes in effect


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## Gary in WA (Mar 11, 2009)

http://www.adoproducts.com/duro.html

http://www.bergerbuildingproducts.com/productsAccuvent.html
1"------

Gary


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