I know, I’ve mentioned this topic several times, but the topic is worth repeating because so many writers get “comprise” wrong. Here’s one of the few who got it right.
Remember: Compose goes from the parts to the whole; comprise goes from the whole (usually a singular) to the parts, which are usually plural. So “barndominiums” is the whole thing (a company, not a bunch of places), and “25%” is the part, which can be either a singular or a plural, depending on how you care to look at it.
Here’s a picture of a barndominium: