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-   -   Attic Ventilation Channels with Skylights (http://www.diychatroom.com/f9/attic-ventilation-channels-skylights-39911/)

Vermont1 03-08-2009 06:19 PM

Attic Ventilation Channels with Skylights
 
I am installing Durovent channels in my 2X6 ceiling rafters as part of my attic remodel. I have 3 skylights in the middle of the roof. Should I NOT put channels in those bays? My thinking is, air will flow up from the soffits and basically stop at the window. I was thinking it would be better not to put the channels there as air will go up and hit the window bottom plate which may cause moisture issues???

Any advise would be greatly appreciated.

Ed the Roofer 03-09-2009 01:16 AM

The Air Vent site is down right now, but try later on and view this brochure regarding ventilating rafter bays that have an obstruction in the air flowage path. It is on the very last page of the brochure, with diagrams.

http://www.airvent.com/pdf/literatur...s_HipRoofs.pdf

But, yes you do want to install the insulation baffle chutes, leaving approximately a 1/4 inch gap between each one as they are laid out and when you get up to both the bottom and the top curb nailers that are obstructing the path, you need to drill 6 of 1" diameter holes in the center of all of the affected rafters, below and above the shylight. This will allow for a sufficient amount of cross ventilation from those rafter bays to the ones that run continuously from the eave to the peak of the roof.

Ed

Vermont1 03-09-2009 03:18 PM

Question regarding your response
 
Tnanks Ed, I will check the site out as well. You mentioned 1/4" gap between each chute. I did 1" as instructed by their website. I already installed. Is it a big deal?

Quote:

Originally Posted by Ed the Roofer (Post 242062)
The Air Vent site is down right now, but try later on and view this brochure regarding ventilating rafter bays that have an obstruction in the air flowage path. It is on the very last page of the brochure, with diagrams.

http://www.airvent.com/pdf/literatur...s_HipRoofs.pdf

But, yes you do want to install the insulation baffle chutes, leaving approximately a 1/4 inch gap between each one as they are laid out and when you get up to both the bottom and the top curb nailers that are obstructing the path, you need to drill 6 of 1" diameter holes in the center of all of the affected rafters, below and above the shylight. This will allow for a sufficient amount of cross ventilation from those rafter bays to the ones that run continuously from the eave to the peak of the roof.

Ed


tinner666 03-09-2009 03:26 PM

Shouldn't be. You do need to dril those holes through the rafters on both sides, above and below the skylights though.

Ed the Roofer 03-09-2009 06:02 PM

Quote:

Originally Posted by Vermont1 (Post 242329)
Tnanks Ed, I will check the site out as well. You mentioned 1/4" gap between each chute. I did 1" as instructed by their website. I already installed. Is it a big deal?

No, the spacing per the manufacturers specifications take priority.

The reason for the gap, is so that any incremental accumulation of vapor does not have the opportunity to build uo and start flowing downhill and appear as a roof leak. The exposed minimal portion of insulation will diminish the potential of that occurring.

Ed

Ed the Roofer 03-09-2009 06:04 PM

By the way, the Air Vent site was working just now.

Ed



Skylights
Valleys

When a cathedral ceiling ends in a valley you canít access the soffit vents for intake ventilation. The solution is to drill six 1" holes in the rafter that intersects with the valley. These openings will allow intake ventilation.

When a skylight is installed in a rafter bay, it basically blocks the rafter bay. To unblock it, drill six 1" holes (horizontally) in the rafter below and above the skylight or other rafter bay obstruction, such as a chimney.

Vermont1 03-09-2009 07:03 PM

Perfect. Thanks Ed very much.

Quote:

Originally Posted by Ed the Roofer (Post 242418)
By the way, the Air Vent site was working just now.

Ed



Skylights
Valleys


When a cathedral ceiling ends in a valley you canít access the soffit vents for intake ventilation. The solution is to drill six 1" holes in the rafter that intersects with the valley. These openings will allow intake ventilation.

When a skylight is installed in a rafter bay, it basically blocks the rafter bay. To unblock it, drill six 1" holes (horizontally) in the rafter below and above the skylight or other rafter bay obstruction, such as a chimney.


the skylight or other rafter bay obstruction, such as a chimney.


Vermont1 03-09-2009 07:34 PM

Ed, just reviewed that site. My first take is that the holes need to be drilled 1" from the roof deck penetrating into the air channel that is in the next bay. I just thought about this again, and realized that the channel in the next bay is in the center and the air flowing out of the holes will hit the insulation. So, I don't get how the air flowing out will get out through the ridge vent. Do I build some type of air channel out of wood from where I drill the holes at the bottom to the holes on top of the skylight?
Any thoughts?

Quote:

Originally Posted by Ed the Roofer (Post 242418)
By the way, the Air Vent site was working just now.

Ed


Skylights
Valleys


When a cathedral ceiling ends in a valley you canít access the soffit vents for intake ventilation. The solution is to drill six 1" holes in the rafter that intersects with the valley. These openings will allow intake ventilation.

When a skylight is installed in a rafter bay, it basically blocks the rafter bay. To unblock it, drill six 1" holes (horizontally) in the rafter below and above the skylight or other rafter bay obstruction, such as a chimney.



Ed the Roofer 03-09-2009 08:23 PM

So, you already have all of the insulation baffle chutes installed?

I presume if you intended to be able to drill into these rafters, you obviously still had access to the rafter bays. If so, you couls re-position the insulation baffles, so that they are right next to the rafter with the holes drilled in them, continuing that path all the way up to the peak of the roof, where the ridge vent will be located.

As another option, DCI Products Inc. has a product that they have made for placing in top of the rafters, prior to installing the plywood deck sheathing.

It is called Rafter Vent and here is that link:

http://www.dciproducts.com/html/raftervent.htm

Ed

Ed the Roofer 03-09-2009 08:25 PM

By the way, I do not have any personal experience with the Rafter Vent product, but I have used their Smart Vent for Intake Ventilation repeatedly for about 6-7 years now and am very pleased with its performance.

Ed

Vermont1 03-10-2009 07:54 PM

I think this should work. I will give it a try.. Thanks for your help.

Quote:

Originally Posted by Ed the Roofer (Post 242477)
So, you already have all of the insulation baffle chutes installed?

I presume if you intended to be able to drill into these rafters, you obviously still had access to the rafter bays. If so, you couls re-position the insulation baffles, so that they are right next to the rafter with the holes drilled in them, continuing that path all the way up to the peak of the roof, where the ridge vent will be located.

As another option, DCI Products Inc. has a product that they have made for placing in top of the rafters, prior to installing the plywood deck sheathing.

It is called Rafter Vent and here is that link:

http://www.dciproducts.com/html/raftervent.htm

Ed


Ed the Roofer 03-11-2009 01:26 AM

You are very welcome.

Please come back and post again when you are working on the project, with "In Job Progress And Completion" Photos regardless of how that product works out for you.

I would tend to believe that it should do just fine for you and provide an easy and not extremely costly solution for your situation.

Your photos would be a valuable aide for me further recommending the product. :thumbsup:

Ed

Scuba_Dave 03-27-2009 01:10 PM

My Inspector hasd me drill the ventilation holes too

Vermont1 03-28-2009 09:21 AM

Scuba_Dave, once drilled, did you butt the air channels up to the holes? otherwise the air flow would just vent into the insulation since the baffles are usuallly in the center.


Quote:

Originally Posted by Scuba_Dave (Post 251107)
My Inspector hasd me drill the ventilation holes too


Scuba_Dave 03-28-2009 11:32 AM

No, he said to just drill the holes to allow any moisture & heat to escape. My vents are not "air tight" against the plywood. Heat rises so it will find its way out
I've been thru one summer & 2 winters & no problems
I do have (2) 606 venting skylights & a 3rd 306 venting
Below these I have 3 matching non-vented skylights
So there isn't a lot of room for air to flow & air will not flow up to the bottom polate of the venting skylight. The channel below the fixed skylights allows air to vent outside

It was the dead spce between the sets of skylights that the Inspector was concerned with.

My recessed lights are CFL's - so not as much heat going up into the spaces. I also used R38C insulation - cathedral ceiling


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