We're adding a new bathroom in the basement of our 1920's house. The exhaust van duct needs to be vented to the exterior. The basement walls are very solid, poured concrete. The electrician wants to cut a hole in the wood 2x10 rim joist above the concrete wall. Because this 2x10 rim runs perpendicular to the joists, I don't think it would be a problem structurally, but cutting a 3" diam. hole in the side of the house makes me nervious. Any thoughts?