Soffit vent is blocked. Weird. I don’t know what to do.
We live near Chicago and recently bought a 55 year-old, ~1200 sq ft ranch house with a relatively low roof. We are trying to install more insulation in our attic (there is currently ~3″ of blown-in insulation). In the process, we found all kinds of references that you should not block the soffit vents, need to maintain air flow, etc.
While we have 14 soffit vents visible from the outside (each is 2 panels each 4″ x 8″), the vents do not seem to have direct flow into the attic. There is a vertical pressed wood board mounted between the rafters which we initially thought was blocking the direct air flow (the pressed board is pretty much flush with the roof). This board is basically an upward extension of the wall, so the soffit area is apparently a separate triangular channel all the way around the house. In one location this vertical board is missing, and we could take pictures down into the cavity. But it looks like there is a board laying directly on the soffit. So, we used a small probe through the soffit vents from the outside and it looks like they are probably blocked by a board as well. When we tried using a leaf blower to force air into the roof through the soffit vent, the person in the attic could smell some fresh air but could not detect any kind of additional air flow either visually (i.e. no cobwebs or insulation were moving) or with their hand.
So, what do we do now? Since the soffit vents are apparently blocked, should we worry about opening them? Or should we assume that since the house is 55 years old (the roof itself is at least 7 years old) and the roof is in good condition, that we should just leave it as is and just go about putting in our attic insulation? Or is the air flow something that is critical and we should remedy before putting in our insulation?
Our original plans for the insulation were to put blow-in insulation to finish filling up to the joists (another ~3-4″ of blow-in), and then rolls over the joists. We were going to use the rolls so that when we want to put up additional ceiling lights, etc we can roll up the insulation to find the electrical conduits and the joists to walk-on. This issue with the soffit vents has made us question whether we should be installing the insulation ourselves.
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Replies
Mansig Yoon,
Attic venting is overrated. However, it is usually required by building codes. Moreover, adequate attic ventilation can reduce the chance of ice dams. So if your house has ever suffered ice dams, you should fix the problem you describe.
The easiest way to fix the problem is probably from the exterior. Simply remove the soffits; drill holes in the blocking between the rafters, or cut openings in the blocking with a Sawzall; and install new ventilated soffit material. Of course, if you are adding more insulation, you'll also need to install ventilation chutes on the attic side.
If you haven't ever had ice dams, and if your attic shows no signs of moisture problems (discoloration, mold, or rusty nails), you can ignore the ventilation problem if you want. For more information on these issues, see All About Attic Venting.
Finally, it's worth pointing out that most attic moisture problems have nothing to do with insufficient ventilation; they are caused by air leaks in the ceiling under the insulation. For more information on this issue, see Air Sealing an Attic.