Bricks, Masonry, Asphalt and Concrete - Hole in the wall

I recently removed a Selkirk chimney from my house. It went through my basement (block wall) into the rec room. Now I have a 12" hole going through the wall.

I plan on refinishing the rec room so stripping it down to the block wall on the inside is no problem. But, I am not sure what to do to fill and seal the hole from the weather. Also, the exterior of my house is stucco, again, not sure how to fill and seal to the weather.

Thanks,
Bill

You could just try and fill the Hole with a Mortar Mix. You may want to pickup some concrete Bricks from the Home Center. Using them first to plug the "Cell" in the Block,maybe adding pieces of Brick as you add the Mortar Mix to help prevent the Mortar from sagging. When the patch is set enough to the touch you can smooth it out with a 6"x6" carpet swatch or even a damp sponge to try and get the texture similar to the Block wall. (The patch will liable to be rough and sticking out, at this point you can address this). The outside would be done the same way. Though leave the patch back 1\8" to 1\4 from the Stucco depending on the thickness of the existing Stucco. Then you will have to search for a Stucco supplier to try and find a close match for your Stucco. Thats if matching is a concern.

Note: Most of your Materials except the Stucco mix can be found at your local Home Center. A Mortar Mix and some Bricks. You will also want to pick up a "Margin Trowel". This will be a Trowel the is about 2"W x 4"L . You can apply and smooth the patch with this. Matching existing Stucco will be next to impossible so all you can do is get close.