Install baffles in attic with ridge vent?

[TheGadfly]

I just had my roof replaced and they cut an edge vent because the soffits are all clogged up with cellulose insulation. When I was preparing my attic for additional blown-in insulation (sealing top plates, etc.) I noticed that the edge vent is located very low when viewed from inside the attic. It's maybe 10 inches above the top of the joists.

I'm planning to blow-in enough cellulose insulation to bring the R-value to 50 (about 16 inches). I'm worried that the cellulose will cover up the edge vent. The guy who installed the roof said I should be fine as long as I aim the cellulose blower just below the edge vent line. Now I'm wondering it I'd be more prudent to install baffles just to make sure there's 1 inch of clearance below the roof deck and possibly prevent the new cellulose from getting blown around by the air coming through the edge vent.

Anyone have experience with this?

[Jon Bon]

You need air to be able to get in down low, and exit out the ridge vent. How flat is your roof here? the ridge vent is only 10 inches above your insulation? Saying he highest part of your attic only has 10 inches of clearance? Please explain.  Are you sure you know what a ridge vent is?

Do you have soffits? And you said they were all clogged? I would push some of that out of the way and install some baffles if you want to go crazy with the cellulose.

It is all pretty simple really. You need cool air to enter in your attic in the low part, and hot air to exit out the high part.

[TheGadfly]

Yikes sorry. I'm messing up the terminology. I'm actually talking about the edge vent, which runs across the lower end of the roof. I'm going to revise the OP

[lthenderson]

Edge vents are typically installed on houses where there is no overhang and they are for air intake so they do need to be as low as possible. So yes, you need to prevent them from clogging. However, my concern would be the area between the edge vent and your clogged soffit. With no airflow in that region, you could have serious problems with ice damming and leaks if there was a source of warm air in that area. Rather than install an edge vent, I would have cleaned out the soffit vents and installed baffles from there up to above the level of the insulation. Installing edge vents was a lazy and cheap move on the part of the roofers.

[TheGadfly]

hmmm, thanks for that explanation. Makes sense now that you mention it. Installing the edge vent was definitely a cost saving measure recommended by the roofing company. This is probably why they made such a big deal about installing an extra wide waterproof underlayment along the roof edge to prevent damming.

However, my concern would be the area between the edge vent and your clogged soffit. With no airflow in that region, you could have serious problems with ice damming and leaks if there was a source of warm air in that area.

Sealing air leaks and insulating the attic should mitigate the risk of damming but, you're right to point this out as a potential problem. The only source of warm air in that area would come from the top of the exterior wall. Ideally I would seal the top plate of the exterior walls. I wasn't planning to do this because they are extremely difficult to reach due to the shallow pitch of the roof. With this issue in mind, I might try to do it anyway.

[salty_monk]

You definitely need a baffle. The plastic ones are inexpensive and depending on your roof pitch you may be able to cut them in half & get two for one...

Can't you drill through the foam insulation to open the soffits back up?