Insulating with batts ?

[8nford]

Putting up proper vent,s on inside of roof . The gap between the top plate and the proper vent is considerable . I see wind baffles are available for purchase . But don,t think they will cover the opening well enough to prevent wind washing. Can i take craft faced batt insulation ,roll it craft side out and place in opening ,then install batts as normal ? Thanks for your time Don

 

[NUTTSGT]

I had to Google "proper vent" as I've heard them referred to as such. I'm not exactly sure what you're doing but I think I understand. Can you post a picture of what you have ?


If I'm thinking correctly to what you're doing, the rolled up battery should work. I would just peel the Kraft paper off.

 

[anythingyoucanimagine]

When I did my garage and attic, I bought (or ripped culls wood down to 3/4" strips) furring strips, stapled them to the sides of the rafters, up against the bottom of the roof deck, then cut & stapled Tyvek to the strips I nailed to the insides of the rafters. From there you can insulate with whatever you want...


Soffit vents, rafter baffles, insulate top plates (you get extra green points for that) and then 1.5" air-sealed channel all the way up to a ridge vent.

 

[Marctrees]

8nford - You need to give a Geo location.

Nowadays they figure venting only in far north climates where you will be heating.

Or in Southern if you will NOT be conditioning the air.... like a livestock barn.

Generally speaking anyway.

Marc

 

[anythingyoucanimagine]

I would imagine you TX/LA people would want to deal with humidity...???

 

[zak77]

What you're trying to do is called air damming, and it's my next project also. I've seen it done by cutting rigid foam to the shape needed then spray foamed in place. I'm not sure i'd foam it to the roof decking since if that ever needs replacing, you're redoing all of the foam a second time. I'd at the very least do the sides and bottom and where it meets the proper vent. I'm not sure i'm going to use rigid foam, but possibly a product like luan since all you're looking to do is stop wind, not necessarily insulate. BUT my approach is this way since i'll be redoing the soffits and it'll be easier to get access from the outside versus the inside.

 

[anythingyoucanimagine]

What you're trying to do is called air damming, and it's my next project also. I've seen it done by cutting rigid foam to the shape needed then spray foamed in place. I'm not sure i'd foam it to the roof decking since if that ever needs replacing, you're redoing all of the foam a second time. I'd at the very least do the sides and bottom and where it meets the proper vent. I'm not sure i'm going to use rigid foam, but possibly a product like luan since all you're looking to do is stop wind, not necessarily insulate. BUT my approach is this way since i'll be redoing the soffits and it'll be easier to get access from the outside versus the inside.

Why not run strapping up the sides of the rafters, against the roof deck then staple Tyvek (or cheap alternative) to give you an air gap --then do insulation if you want? That would keep roof deck safe in terms of moisture, air seal, insulate, etc.

 

[kbs2244]

Is a "proper vent" also called a soffit vent?

If you are insulating the rafters the idea is to provide air flow across the bottom of the roof sheathing.
Between the batts and the sheathing.

If you have insulated the attic floor you don't need to worry.

Air flow is what you want.
More is not bad.

 

[spudley]

Is a "proper vent" also called a soffit vent?

Yep. Just a baffle to allow air to get from the soffit to the ridge.

 

[The Cobbler]

When I did my garage and attic, I bought (or ripped culls wood down to 3/4" strips) furring strips, stapled them to the sides of the rafters, up against the bottom of the roof deck, ......

I did this too, and cut strips of 1/4 luan ply and stapled that to the furring . packed the top plate to plywood with batt insulation.
it's purpose is to stop insulation from filling the cavity so air can move from the soffit to the peak

 

[Marctrees]

I would imagine you TX/LA people would want to deal with humidity...???

So, in our part of the country venting is now in most cases discouraged.

Depends on the exact situation, but the above is generally true.

My wood frame pole building woodshop will be sprayed foam under the roof steel. and walls.

After originally planning to vent... after much study...We used standard NON venting foam closures at eaves and ridge.

I will NOT be putting in an "Attic floor" or anything on my bottom chords.

We will be fully AC'ing it in summer 6+ months.

4/12 roof, the increased Ft3 volume is a minor issue, bottom line no trouble.



Marc

 

[8nford]

Thanks guys for the feed back , some good ideas. I have the foam baffles stapled to the roof deck , a couple inches past the top plate into the soffit. Think i will get some 3/4 in high density and cut and foam in place . Probably take longer to do , but i know it will be sealed. Northern Wisconsin is imperative to have air flow from vented soffit to ridge vent . Thanks again for you ideas . Don

 

[Marctrees]

Being in N WS I agree.

Totally agree w ridge outflow and soffit intake in that Geo area.

Marc