Install Dormer vent?

I am in Los Angeles. My home has no soffit venting. The soffit is stuccoed so it would be difficult to install soffit venting. I was thinking about installing some dormer vents. What is the best way to cut through the asphalt shingles? I assume that once the roofing is cut I can just slide the dormer under the shingles. Do I need to seal it with anything?

Remove a wider path of shingles than the size of your dormer, so that you can apply the side wall step flashings and then reshingles over the steps.

If the unit already has a roof metal flange, I would cover the entire flange with Grace Ice and Water Shield first before applying the shingles.


This is a prefabricated sheet metal dormer vent with a full flashing around the perimeter. I was hoping to not replace any shingles & just slide the dormer into place.

If you want it to leak, then that would probably happen if you do not remove the shingles first.


Why? The shingles & felt go over the flashing to begin with.