Hi Audi, I have a 28'x36' barn/house which is insulated with used foam as well. It came off some flat roof from somewhere. Some of the sheets were tapered, some 4'x4', some 4'x8', some still had large washer still stuck to the sheets. I also get foam as factory seconds, with voids or slightly the wrong size. All things that make the installation a bit more time consuming. For my own project and money I am happy to use these types of materials. For clients I tend to go with new product, as it installs quicker and so cheaper for them. Or it turns out to be a wash cost wise. I would have no issue using used or seconds if the client so desired.