Attic with no ventilation
I am renovating a house that has an addition that seems to be built incorrectly. The house was originally u-shaped, but is now square. The part that they filled in has roof joists spanning the gap (about 12 feet) instead of running up and down (does that make sense?)
Being in northern Canada, it has about 8 inches of insulation, and due to the low slope, the joists don't allow for any attic ventilation (see attachment for poor drawing) and there has been some water stains and water damage. There isn't even soffit on the outside.
My first thought is to open it from the outside and install soffit, but my question is, can I drill a series of holes in the joists to allow airflow through the lower, clogging joists? I have found sites that say you can drill up to 3" on 2x10s, but how many can you put in?
The moisture isn't terrible, so I'm hoping even a few holes would fix it. The rest of the house vents fine, and the addition is open at the upper end of the attic.