Ownership of Design and Design Documents

In our contract, we claim ownership of the designs when we provide them. Here is a note from a potential client after reviewing the contract.

“Out of curiosity, if we have paid to have the plans drawn up, then why don’t we own them?  I’m assuming this is some sort of industry standard thing but I’m curious as to why.  Not that I think this is likely, but I can vaguely foresee situations where we are forced to abandon ship half way there.  Of course, we’d want to pay you for all costs incurred and work done etc.  But having done so, why aren’t the documents ours, so that at some later date we might restart the effort?”

Response - This is an industry standard as the client suggested. We specifically include the claim so that we can use parts of the design to build other jobs down the road without fear of copyright infringement.