I have a chimney that goes from the ground level through the roof (overhang) on the FRONT of my house. My house is a rambler with a basement but the chimney does not go down into the basement and was built in early 70's.

I would like to remove the chimney and fireplace and replace it with a large window. It appears that the chimney comes out from the front of the house about 2 feet so I think it is totally external on the house (other than the actual fireplace inside. There is also a small gable on the roof behind the chimney to help water flow around it.

How complex is it to take out the external chimney and is it likely to be a structural part of the house? I am planning on reshingling the entire house so the roof shouldn't be an issue other than needing to patch that area. There would also not be any roof trusses going out where the chimney used to be so I'd have to figure out a way to provide support for that area on the roof. My other concern is what do I do at the base (underground). Is it usually built outside the main foundation of the house so all I need to do is go down below ground, slope the dirt away from the house and put my mulch covering over it?

Any thoughts would be appreciated...

The truesses are already supported without applying load to the fireplace or chimney. I think you will find that the foundation of the fireplace is more massive than you picture. It is usually outside the perimeter of your foundation but can be a soild block of concrete or at least a footing as deep as the rest of your foundation. You can jack hammer much of it and then back fill without hurting the foundation strength.

Thanks, that helps. Would there be any reason that I couldn't just leave the foundation of the chimney in place? It would be under an area of landscaping and I would have no reason to remove it. I can just put mulch chips and dirt over it once I get down to it and just avoid planting flowers there. Also, any ideas on how to support the roof where the trusses have been shortened to allow for the chimney?

If you can see the foundation and it does not bother you then keep it. The trusses already carry the full load of the roof so all you need to do is extend thetruss span with 2x10 or 2x6. I think you need to go 2' so use a 6' piece of 2x10 glued and screwed to the truss side.

Had the same issue at my sons house, all we did was tie a strong rope around the chimney and tied it off to my pick up and away I went and the chimney came down. Left all the footings and picked up the bricks and thimble liners, all done.

I saw a guy on TV do something similar. He used a 35" chain to pull down a 40" silo. Guess what happened.

They are spectacularly easy to knock over and dangerous as all get out, the perfect hobby, right? My neighbor built his own unfortunately he didn't keep the mortar wet to cure it at all and a big gust of wind knocked it flat a few weeks later, almost took out his truck parked in the yard. The chimney is totally freestanding and can't be supported by the house framing to keep it from catching fire from the heat inside. Sometimes a house or cabin will burn down and all that's left is the chimney standing there. Take as much or as little as you want away. In my experience the foundation for a stone or brick chimney can be poured as deep as 5 feet this stabilizes it to keep the massive weight from tilting away from the house leaving a big crack between or alternately from heaving due to frost and starting to lean onto the house.