Sure thing, manual labor needs to be figured into the plan, when creating a diet/workout program. You are expending a lot of extra cals and will probably require more food than if you worked at a desk. That doesn't mean that you shouldn't do cardio as well but it all depends on your goals. If you are trying to get ripped, you may still need to add cardio in. It's going to come down to your diet. If you are in the off season, and you have a hard time gaining fat or muscle, you'll probably want to limit the amount of cardio you do. If you are in contest mode, I'd start you at 30 min post workout and see how you responded.