You likely hear people talk about protecting your walls from rain during construction. Surely this sounds like a good idea and it is indeed something I agree with…to some extent. To me, the most important aspect of protecting your walls is to make sure that no water makes its way onto the top of the bales. Of course, if it is going to rain for a long period, then protecting the walls from rain on all sides is a good idea, but if it’s an occasional rain shower then the tops are truly all that matter.
Consider what you do before plastering the walls. Yes, you spray them with a hose to get them wet. They can handle some water on the sides, it’s the nature of the material. If you look at a straw bale, you’ll notice that it has different sides: a cut edge and a folded edge. The cut edge does a great job of draining water away and the folded edge does as well. The problem comes when water is dropped down into the top of the bale because it can then settle into the middle of the bale from which it has a hard time draining (unless laid on edge to drain which you can’t do once the house is under construction).
As your course go up, be sure to cover their tops, especially at the end of the day if rain is in the forecast. I would not suggest that you bale with the wall covered the way it is in the picture. This was at the end of the day. If you are experiencing a lot of rain and your overhangs are not adequately protecting your walls during construction, then hang tarps from the eaves (or even better…build better overhangs!). In most cases, you should be able to build without added protection and should simply protect the walls as shown at the end of the day. There’s nothing quite like waking up at 3am to a massive rain storm and saying to yourself “I really wish I had covered the bales. I hope they’ll be okay.”