How would you handle this eave detail

[J.Buesking]

The batten insulation in between the rafters has no venting. I'm going to handle the venting issue in between two sheets of plywood using 2x4's as runner's on top of the rafters.

Not sure about the vented drip edge. Not even sure If I can get it.

[Ted S.]

Re: How would you handle this eave detail

I'd make the metal two pieces. The first piece which laps into the gutter I'd run it up under the 2x4 sleepers in between the plywood. Lap that with the ice an water, you'd have to shingle it in. The second piece would be more of a standard drip on the top sheet of plywood. I'd keep these fabrications pretty simple. Then inbetween the plywood I'd put some venting material, the stuff that looks like freeze dried pubic hair.

That detail looks like an architect drew it, it could be made but the venting would be hard to do.

[J.Buesking]

Re: How would you handle this eave detail

It actually will be two pieces. The architect left out the cleat. The cleat will run up onto the first layer of sheathing.

My original suggestion was something like freeze dried pubic hair with two drip edges that are cleated.

[THWagar]

Re: How would you handle this eave detail

In MN I think the metal venting would be full of ice in the winter so air couldn't get to the chutes. I think your around Atlanta?......so may be okay.
I'm not sure how good the air would flow down into the gutter and the up into the bays...............one idea may be to put some coravent between the gutter and fascia so the air moves up behnd the gutter into the bays.

What is the horizontal stuff below the gutter? I may not be seeing this right.

[David Meiland]

Re: How would you handle this eave detail

Need the shingles to overhang the vented metal by an inch. That flush detail as shown will not perform, you could actually get water sucked up into the space between the sheets by airflow. The shingles have to clear the drip edge, the drip edge has to clear the venting... so I pretty much vote for Ted's plan. TED 2012.

[J.Buesking]

Re: How would you handle this eave detail

The shingles would hang over 1".

That is not shown but will happen.

[AndyGump]

Re: How would you handle this eave detail

Why not just put 1 1/2" XPS on the "fire treated plywood"?
You can sheet over it (if you want) and install the roof material and call it a day..or two.
It is code compliant for non-vented attic areas.
Then no need for venting schemes.
Here is a link to IRC 2009 on non-vented attics. http://publicecodes.citation.com/ico...006_par003.htm

What is your location?

Andy.

[Alaskan Son]

Re: How would you handle this eave detail

We did a very similar job last summer. We ended up drilling holes through the origibnal main layer of roof sheathing down at the eves to allow air up into the new ventialtion area.

[DonMirabito]

Re: How would you handle this eave detail

What about using cor-a-vent in-vent???

Don

[clydewater]

Re: How would you handle this eave detail

If you are trying to tighten up the house, then maybe a layer of Tyvek over the existing fire treated plywood below the 2x4s
As others have said, the shingles should extend at least 1" beyond the metal vent, but I think CoreVent is a better choice and pull the new plywood back toward the edge. I do not think your drawing is to scale, but if it is the extra 1" of shingles is going to possible let the water miss the gutter in a hard rain.

Do you have freezing issues where you are located? If so, then square gutters will deform when ice forms in them.

[J.Buesking]

Re: How would you handle this eave detail

This is a type II fire rated hospital. Due to fireproofing and existing design we can not open the soffits up to allow venting into the conditioned air space. It's basically an attic with a structural concrete floor that houses all the mechanicals. The current insulation lays flat against single layer of sheathing. Cooking the plywood and shingles. It's a complete tear off to the metal framing now.

I like the idea of cutting holes into the first layer of sheathing but being fire rated I can't.

Right now the existing plywood is cooked to the core. It crumbles. So we are tearing to the frame and building venting on the outside. This will prolong the life of the shingles and other materials.

It's 7" box gutters that are plumed into internal drains. Typical in this area on commercial buildings. Currently the building has internal gutters that have leaked since 86 when the original construction was completed. We are tearing them all out. Going to a metal framed cornice detail and external gutters. Per the engineers spec's.

I like the coravent and had suggested it already. This sketch is what was sent back and asked for my thoughts on even though i'm sure my thoughts mean nothing. :)

[philthegreek]

Re: How would you handle this eave detail

Some questions;
1. what is down slope of the gutters?
2. what is the thickness of the sheathing?
3. why 2x4's and not something thinner like 1x material
4. standard asphalt shingles?
5. what is the gutter's box structure material ?

Phil

[J.Buesking]

Re: How would you handle this eave detail

1) Gutters are spec'd to be perfectly level. I know not ideal but engineer sited the smacna manual and decided level was ok after myself and owner questioned it.

2)3/4" Sheathing both layers

3)I can't think of anything that is cost effective that would be nominal 1" compared to an inexpensive 2x4.

4)Standard 300lb landmark premium dimensional shingle

5).040 aluminum gutters.

[AndyGump]

Re: How would you handle this eave detail

I have to say that I doubt very much that the sun and the previous non-vented design could "cook" the shingles or the ply on the original deck.
Unless it gets about 300 deg. on it.
I would ask your archy about a non-vented design. That might save you thousands of dollars on material and installation.

Andy.

[J.Buesking]

Re: How would you handle this eave detail

I wouldn't have thought so either but the conclusion is that it's a combination known issues with fire retardant plywood or possible bad plywood from the 80's. It's not rot. It's chared. Turns to dust and is very brittle. You can barely touch the plywood from the underside on a 80 degree day so I'm a believer. The inside mechanical room is controlled at a average 70 -80 degree's.

It has been suggested to redeck it but we can not get a shingle warranty due to lack of venting. It's roughly 865 sq.

It's not my engineer or my building. Just the contractor trying to get this project completed.