They are doing work for your benefit, should you close off your bathroom to them?

You have someone coming to your residence to do something that is very time consuming, putting in a deck, doing roof work, putting in a home network and stringing cable all around, painting, etc. it is plausible they may need to relieve themselves, it is unreasonable to close off your bathroom and deny them use of it, or not? If they are working outside do you expect them to pee in some corner of your property, that they should leave, go find a restroom and then come back? How would you handle such a situation?