Originally Posted by
ian
This looks like there was a doorway here sometime in the past.
more importantly, from what you write, I'm guessing you are something like the 10th or 11th owner of the property.
Given your age, you are unlikely to be a victim of one of the asbestos diseases -- you more than likely will be dead before the dust disease gets you -- but your kids and grand kiddies could be at risk.
How sure are you that the property has never been sheeted in asbestos? That none of the dust you are discovering is not contaminated with asbestos? Perhaps ban them from the house till after the reno work is completed. Once you have fully cleaned up, including all the dust residual risk should be minimal.