One of my roommates was insanely messy. My other friends and I made a giant sheet out of duck tape and put everything he owned and all the trash he made on it. I mean everything too, clothes, his Xbox, TV, motorcycle helmet, keys to his car, dirty pots and pans, empty bottles, ****ing everything. Then we wrapped that ***** in 75 bucks worth of duck tape. The kid is so messy that he never even unwrapped the ball. He cut a couple holes in it, and whenever he'd need something, he'd just rummage around inside it until he could find it.
On the actual topic, you are on the right track, talk to the builder. I'm sure you will get something worked out.