Nope.
That’s the short answer that you should hear from every chimney professional. Your fireplace can never be considered “safe” no matter what repairs we may do to it. “Safer”, yes, but never “safe” Why is that? Why can no chimney sweep ever say your fireplace is safe? Two reasons.
The largest stainless steel liner I have personally installed. 12″x24″
We didn’t build the chimney and it’s likely we didn’t supervise its construction. There are hidden areas of your chimney, behind walls and other areas, that are completely invisible. All the video cameras in the world won’t reveal some of these areas, and there can be disguised dangers there. Did the original contractor obey every single clearance to combustible 100%? Or is it more likely there may be a shortcut or two that was taken along the way. Has there been damage to the structure that went unseen because it was behind a wall? We may never know unless you’re willing to start tearing walls down, and I have yet to meet the homeowner that was comfortable with that idea. Unless we suddenly develop x-ray vision, there may always be areas of concern that are locked away from a traditional inspection.
We can’t stay at your house and monitor you having a fire. Human error is one of the biggest reasons chimneys experience a catastrophic event. Poor use and poor maintenance can have serious consequences. Will you use the fireplace properly after we’ve been there, with common sense safety standards? We don’t know, and we’re not willing to bet on it. I can make your chimney the safest it can possibly be with my skill and knowledge, but if you turn around and put firecrackers and gasoline in there all my work means nothing. If you had a car accident because you were speeding, you wouldn’t look to the mechanic who changed your tires last. Same principle applies with chimneys. We do the best we can, but if you don’t use the appliance properly you can have bad results.
So the short answer is still “nope”. Your fireplace will never be 100% safe guaranteed. But proper maintenance and repairs when needed, plus a healthy amount of common sense can have you enjoying a fire with peace of mind.