now you know why people's homeowners insurance premiums are so high- I feel for you friend but you really ought not be doing industrial activities inside your home.
Last Thanksgiving 27 homeowners burned down their house by deep-frying turkeys inside their garage so they wouldnt have to be "out" in the weather.
Even without that going on...you should have a fireproof mat in front of that fireplace anyway, so you ought to do that.
If your contractor left you any spare pieces of carpet, and he should have, you can patch that and no one will know- go to DIY.COM and it will show you how to patch carpet.