A few thoughts come to mind.
[ul]
[li]Unless you stop your employees from saving the files to their computer they're going to be able to take copies of anything you have. Even if you stop them from saving the files, you're probably not a good enough IT expert to stop them taking them some other way (copy + paste to another file?). And if you do stop them saving the files then how are they supposed to work for you? Your drafties will need to save drawings and your engineers will need to save calculations. The costs of stopping this from happening are probably higher than any benefit.[/li]
[li]Why are you concerned about employees taking your tools to another company anyway? I can understand proprietary information and data, or computer code for products etc. These will be protected by copyright / patents etc. and ultimately your lawyers.
But if it's just calculation templates that are based on industry wide standards (e.g. AS/NZS here in AUS, ACI / AISC standards in US), or standard details that are pretty much identical to the same standard details everyone else uses then one of two things applies:
[/li]
[ul]
[li]Either you're worried because they're a good engineer and will potentially be competition if they go elsewhere. If that's the case, then a) why let a good engineer go - pay them more, give them better conditions or whatever. And b) good engineers will already be building their templates, calculations etc. They probably don't want to use yours anyway, because they don't understand exactly how it works, and it's not set up to suit their preferred workflow. Most good engineers have a terrible case of "not built here" syndrome.[/li]
[li]Or they're a bad engineer. In which case your templates won't make them any harder to compete with if they leave you. And if they screw up so badly something falls down then it's very unlikely you'll get blamed through a spreadsheet from years ago that they didn't use correctly.
[/li]
[/ul]
[/ul]
Maybe it's an Australia vs US thing, or a small company vs big company thing (I've always worked in small companies), but in all the places I've worked people have actively encouraged their employees to build their toolbox of standard calculations and reference info, or at least winked and looked away while you did it ("what I didn't see you copy + paste can't hurt me"). My current director specifically tells all the new grads to build a reference library of documents, spreadsheets etc., and to take the time to understand the tools they are using and developing. Provided you give something back (help develop the company's standards in return etc.) nobody seems to mind. I can't think of a single (good) engineer I've worked with who didn't have a vast collection of spreadsheets, standard drawings and reference calculations from current and previous employers. Some of it may be legally questionable but no-one cares either, provided you're not:
[ol a]
[li]Using proprietary data, customer information, computer code for customer facing apps, internal research etc. - that's a big no-no.[/li]
[li]Using it to sell yourself or your new employer (e.g. "hire me because I have all the spreadsheets from previous employer xyz").[/li]
[li]Pretending to be someone else / some other company (that's Fraud anyway).[/li]
[/ol]