Ah, I just sent you an email on this. Your GL policy has an EXCLUSION in it, for damage to YOUR WORK. So, if you drive into it with your car, your auto policy does NOT have an exclusion, as long as it belongs to someone else, it's covered under your property damage liability of your auto policy.
But damage to YOUR WORK, including but not limited to faulty workmanship, is specifically excluded under your GL policy.
There MIGHT be some coverage for an accident (but not faulty workmanship) under the builder's risk or installment floater in place, by the GC or the owner. On the CGL form, refer to exclusions, section j. damage to property, paragraphs 5 & 6 - excluding damage to the part of real property that you or any contractors or subs working directly or indirectly on your behalf, performing operations, if the work was incorrectly performed by you, and K & L, property damage to your product or work, including products & completed operations.
Might be TMI, if you've even read this far . . .