As many of you know, most CAD files will not insert seamlessly into Visio for use as a “background” so that you can mark them up with SI5 shapes. We have full documentation here (third section) on how to correct the common error received as well as how to break a CAD drawing into smaller drawings. The problem though is that you need some sort of CAD program in order to complete the steps. Many of our clients do not have the full version of AutoCAD but have a LT version on at least someone’s machine within their company. Others do not and then must try to get the architect/builder you are working with to perform the steps so that you can use the CAD file, not always an easy task depending on who you are working with.
DraftSight by Dassault Systemes may be a good solution for you. This free software allows you to perform all of the steps that we have outlined (plus a whole lot more) in order to get a CAD file Visio compatible. You must provide them an email address and activate the software but well worth it if you get some emails from them occasionally in exchange for a free CAD editor.