I would buy one to keep them dry at the moment. My boars have their Pighouse so it's covered but if they are in their run and it looks like it might drizzle , then I put an old waterproof shower curtain over the run (It covers the top, secured by pegs. Sides are clear)
You need to make sure they've got enough ventilation. But I think it's worth it to keep the hutch dry (apart from all the pee. You can't stop that)
Great thanks, I'll get one then. They have the type where the hutch is on top of the run but they are too scared of the ramp to go up it I think so I need to do DIY on it to make it less steep. I put a hidey house in the run and they go under that when they want to snooze/hide.