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-   -   Soffit Vents (http://www.diychatroom.com/f19/soffit-vents-97287/)

Atskodinski 03-04-2011 11:09 PM

Soffit Vents
 
In the process of updating my attic ventilation. Current question pertains to my soffit intake vents. I plan to balance intake/exhuast at 1NFA/150ft2.

The current soffit is aluminum and while it appears to be perforated for airflow, I checked underneath and sure enough, there is a solid board underneath. Based on how everything else in this house has gone (built in '56) I'm feel fairly confident that the soffit is solid wood the length of the house. My dad feels there should be holes cut in the wood for ventilation prior to the aluminum soffit being installed. I agree that it "should" be that way but really don't think it is based on the current ventilation set up (1 12" turbine for 1500 ft2 of attic space).

This is what I want to do.... Determine how many 16" x 8" soffit vents I need based on my exhaust system and NFA calculations. (Going to be around 11ish). Then go around the perimeter of the house and drill/cut through the aluminum/wood soffits and install the vents evenly spaced.

Anyone see any issues with my plan?

md2lgyk 03-05-2011 06:18 AM

Do you have any roof vents? A ridge vent? The air you want to let in has to get out somewhere.

Jackofall1 03-05-2011 06:28 AM

I would be looking at equivalent mushroom caps or ridge vent (but that would mean more roofing work) as opposed to a turbine vent, to attempt to get more uniform flow through the attic.

Mark

Edit - heres a great site if you are interested

http://www.buildingscience.com/docum...ic-ventilation

Ron6519 03-05-2011 09:55 AM

Quote:

Originally Posted by Atskodinski (Post 602708)
In the process of updating my attic ventilation. Current question pertains to my soffit intake vents. I plan to balance intake/exhuast at 1NFA/150ft2.

The current soffit is aluminum and while it appears to be perforated for airflow, I checked underneath and sure enough, there is a solid board underneath. Based on how everything else in this house has gone (built in '56) I'm feel fairly confident that the soffit is solid wood the length of the house. My dad feels there should be holes cut in the wood for ventilation prior to the aluminum soffit being installed. I agree that it "should" be that way but really don't think it is based on the current ventilation set up (1 12" turbine for 1500 ft2 of attic space).

This is what I want to do.... Determine how many 16" x 8" soffit vents I need based on my exhaust system and NFA calculations. (Going to be around 11ish). Then go around the perimeter of the house and drill/cut through the aluminum/wood soffits and install the vents evenly spaced.

Anyone see any issues with my plan?

Sounds like a plan. The house probably had some venting in the soffit area originally, but the siding guys just ignored their locations and were too lazy to take the time to cut through the plywood for the new vents that lined up with their work. I just went to a customers house to check for insulation in the attic. Saw somebody used a drill to "vent" the soffits when the vinyl went in to cap the overhangs. I'm sure the 5, 1/2" holes went a long way to solve the venting issue.
Ron

Atskodinski 03-05-2011 10:19 AM

Quote:

Originally Posted by md2lgyk
Do you have any roof vents? A ridge vent? The air you want to let in has to get out somewhere.

I'm working with a roofer to put in an appropriate ridge vent. Like I said, I do plan to balance my system. I'm just asking here about my plans for the soffit vents since that is the part I plan to tackle myself.

The other thing I should point out is the existing metal soffit's perforated sections have either been painted over to cover up the holes or they are more decorative in nature. So even if there are holes in the plains above, can't imagine much air is getting through. I currently have 1 turbine that never spins, which I attribute to no intake air (bearings on it have been checked).

I assume to issues cutting/drilling through the metal soffit?

Atskodinski 03-05-2011 12:15 PM

Quote:

Originally Posted by Ron6519 (Post 602890)
Sounds like a plan. The house probably had some venting in the soffit area originally, but the siding guys just ignored their locations and were too lazy to take the time to cut through the plywood for the new vents that lined up with their work. I just went to a customers house to check for insulation in the attic. Saw somebody used a drill to "vent" the soffits when the vinyl went in to cap the overhangs. I'm sure the 5, 1/2" holes went a long way to solve the venting issue.
Ron

Hey Ron, thatnks for the input.

Did some additional investigating and sure enough, I did find a vent screwed into the original wood soffit. Of course, like you said, there is a solid piece instead of a perforated piece over that vent. Obviously not much care went into lining everyhing up or cutting additional holes in the wood soffit. Also can confirm the metal soffit has been painted over which further reduces the openings of the perforforated sections. It seems to me that whatever ventilation currently exists is minimal at best and unless I want to rip down the exisiting soffit to cut new holes, clean the paint clogging the perforated section, I think my plan will still work. Obviously just need to avoid cutting into an existing vent.

4just1don 03-05-2011 12:19 PM

only way I see to get this 'right' is to take off existing metal soffit and then remove all of the plywood, cutting it if necessary. Making sure your rafter bays are open to the peak,,,or sidewalls arent solid to roof. Put insulation baffles as necessary. Put your soffit material back on if it indeed vents,,,if not install 'new' vented soffit.


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