Majority of the property is demolished and rebuilt via a partial demo with an Alt-CO filing with DOB.

Basically I got the house demoed, new roof, new gutters, misc. materials and other minor labor completed for $15k.  

I am beginning renovations on a single family home in West Seattle soon, and the demo and trash generated will be pretty extensive.

Dont forget the permit fee, time, and cost of demo and hauling all the material away.

I don't know them but for that price, it's worth checking out a demo I think. https://coachmatix.com/5.

When you get your demos, ask about data sharing and make them be specific.

There is a garage in the back that is not in a good shape, so I am considering demoing it and making it a parking pad.

That being said, if it's not disturbed, you don't need to worry about it (but this will add to the demo costs when you gut / rebuild.

Be sure to ask for very specific scenarios, locations, and property types that you are interested in since their canned demos only show CoStar in its best light and none of its missing holes.  

We will always give a GC the opportunity to bid the entire job but if his cost is out of bounds then we may give him the demo, plumbing, electric,framing...Stuff that may require permits,  but once everything is inspected & it's time to close up the walls or right after the walls are closed the remainder of the job may go to handymen with the same skill set as the GC, but not the license or overhead.