Spray Foam Insulation Covered Ridge Vent

We’re working on a new project that has roofing sections over vaulted ceilings and over sections with attic space. Our builder did spray foam on the vaulted areas and blown in fiberglass on the ceilings of the portions with open attic space. We’re in Michigan and once we started getting snow there has been massive heat loss and melting/ice damming on all of the areas with attic spaces. The builder was first claiming that everything was fine and that it was “environmental” melting — but that was happening when it was 11F outside…not likely.

Then he changed his story to say that the spray foam contractor screwed up and covered all of the ridge vents and that is what is preventing warm air from escaping. See attached pic that I took during the spray foam process. You can see the vaulted portion meeting the attic portion and it does look like the ridge is completely foamed in. He now says he thinks that 100% the problem and he wants to cut in “mushroom vents” to provide the venting capability. I’m nervous about this because the roof is brand new and I don’t want them cutting a bunch of holes and creating potential leak points. There are several locations like this so I’m guessing we would need at least 6-10 of those vents. Not ideal.

Is there another option to make up for the blocked ridge venting? Thanks in advance for any thoughts anyone can provide!

Your builder may be correct about the foam blocking the ridge vent. I cannot see an opening from the picture as he’s explaining.
For a ridge ventilation system to work it has to draw air from the eave or soffits and pull that air to the ridge where the exhaust exits the attic space. Without the ridge having the proper opening as I’m thinking was the case initially it’s never going work as designed.
Think of it This way, if you open a window at opposite ends of your home you start to feel air circulating in the area between each Open unobstructed window… Now close one window 3/4 the way shut and see if you still have the same air flowing? .
Attic ventilation systems like a ridge vent works the same way. Your contractor may be suggesting mushroom vents to satisfy your wishes after being told he was wrong with the foam situation? I could be wrong take another look at the ridge area and foam then check the manufacturer installation requirements for the vent system you have installed for roof. Good luck and I hope everything works out

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Is the building in the same state as the picture? Or have the demising walls been insulated and drywalled?

@Darkthirty - The house has been drywalled, taped/mudded, primed and painted. See pic below for current status…But, again, this portion of the house only shows a couple of the attic spaces that are having this issue. There are several other areas of attic space adjacent to vaulted ceilings. That is the root of my concern — that we will need 10 mushroom vents cut in and that will create a massive potential leak issue moving forward.

So, I’m curious if we should either tear out the existing ridge vent and try to “cut through” the spray foam, etc to enable the ridge venting or if there are specific processes/products we should use to ensure there are no leaks with the mushroom vents?

You’ll only need venting in areas with voids. The spray foam will not vent. If you have a competent roofer, box vents won’t leak. I used box/mushroom vents on my house because I’ve seen too many ridge vents that were inefficient. What is the R value of the installed foam?

Exhaust vents are needed, but I doubt that alone is going to fix tour ice dam problem.

You need to address heat leaks into attic. Are all of the walls of the attic space airsealed and insulated to match the ceiling r-value? seems like it would be difficult to do with only 2x4 wall studs going up to the peak. I’d take a close look at this wall. Infrared camera shot from inside attic would confirm this.

Ridge vent is not going to work because attic you are trying to vent is not under the ridge.

I assume dimensional composition roofing? 4/12 pitch?

Can vents seem like a good option. A good roofer can figure it out. If it is 4/12 or less I would have them remove all of the top shingles and redo with metal vents, ice shield, and new shingles and cap. Vents should be as high up as possible. If you try to retrofit without removing shingles on a low pitch you are likely going to have 1 or 2 vents leak.

Not a roofer, a builder. You are getting ice dams at the point where the rafters meet the attic I assume.
The SPF is letting that portion of the roof loose almost no heat. The attic portion is loosing heat, and more if HVAC unit or ducts are present. That heat lose is what creates the ice dam. You need to vent the attic, not the spf rafters. It can be done with roof power vents, gable vents or other ways. You want that attic to have air in/ air out.