Hi, working on the big picture here, trying to plan what to try to accomplish this year. I really want to spray foam my rim joists. I also want to install stapleup radiant tubing, so am holding off on the rim joist job till the tubing goes in. Is there anyway I can use spray foam to insulated under the tubing? I am afraid it would eliminate the air space which seems needed to heat the floor. Help! I can't start the actual work till the planning stage is finnished. Thanks.