Expanding the roof opening for the chimney for the 2" clearance all around.

As you recall, last time we put in the chimney and when all was said and done-- we realized we missed a 2" clearance around the chimney to the combustibles-- i.e. the roof. Luckily, there was just enough room to maneuver the tools in order to expand the opening. At first, I marked off the 2 inch clearance location on the sheathing. I then knew how far I needed to cut. The best tool for the job ended up being a so-called Variable Speed Oscillating Multi-Tool.

Sawzall on the left, Multi-tool on the right.

This tool ate through the sheathing like warm butter. With little notches all around the perimeter, I was able to expand the opening to the required 2" clearance. The location where the multi-tool didn't fit (if the blade was longer, it would have worked), I ended up using the Sawzall successfully. After a few hours of work and a trip to the store to pick up some new blades, I had my required clearance of the roof to the chimney. Inspection is coming up next, then the space between the black chimney support box and the roof sheathing will need to be boxed in so that nothing gets in and starts a fire-- i.e. insulation, rodents :) One more important note-- a lot of junk has fallen in to the support box from cutting the roof and later expanding the hole. I need to vacuum all of it out before I close it up!

Closer look at the roof opening clearance for the chimney.

If you look closely, the lighter gray is the outside flashing while the shiny gray is the chimney and a 2" clearance in the roof (that's a pretty big gap!).