The clothes dryer manufacturers have specifications on the duct work. They want ducting not to exceed a certain length, and they want 4 inch rigid metal ducts. A 4 inch duct has twice the flow capacity of a 3 inch duct. The restriction of a 3 inch duct causes the clothes to take much longer to dry and also stress the fan motor. PVC pipe is known to build up a static charge which causes lint to stick to the surface - thus requiring more frequent cleaning to avoid a possible fire hazard. For long 4 inch metal ducts there are dryer booster fans. The radon people have fans that go into 3 inch PVC pipes that run continuously. What I need is something that will essentially double the flow capacity of the 3 inch PVC pipe while the dryer is running. It can sense the dryer fan pressure or whatever and just ram flow through the pipe and be done at reasonable cost. I just cannot believe that duct manufacturers cannot design and custom build devices like this.

There is not a current toilet in the space. Here is my proposed layout: From GWfloorplans The dotted line running E-W between the Master and the hall bath is a beam supporting the floors--used to be an exterior wall downstairs. The only place for a down drain is along the exterior wall (W wall) of the proposed hall bath--at the end near the drawn hall bath toilet (not at the end near the Master bath Toilet. The joists run N-S in this area. The circled S is the location of the current stack for the house/downstairs bath. In this plan, I think the hall bath vanities can be drained to either the toilet lines and W, or to the old stack. The Master bath sinks and shower would require a much smaller down line (what are those called, anyway?), and could more easily be dropped down the W wall again. (under all this space is an open great room).

Alert, Long Post: Thanks Renovator, Worthy, Sombreuil_mongrel, Brickeyee, Weedyacres, Sierraeast, and last but not least, Pam. Ok, the big picture. I have a plan to use slate tile in a Versailles pattern ranging in size form around 6x6" or so, up to maybe 12x16. This is an estimate. This is called the "Small Versailles". The stone varies a bit in thickness and is hefty. It is slate stone from "The Tile Shop". We have a store in the metro area of Des Moines, Iowa. I will be installing this myself. My goal is for the floor to tolerate: 1) the weight and stiffness of this tile & it's underlying compound 2) fair amount of foot traffic 3) 5.5' cast iron tub 4) water for tub 5) vanity with large cast iron sink 6) toilet. 7) I might put tile on the wall and don't know if that extra weight matters. Floor as is: 1) Floor dimensions in finished bathroom is 6.5' x 9.5'. 1) 2x8 joist at 21"OC, about 10' or 11' in length, and about 9.5 free span. See picture above. 2) 3/4 (or 1") x8" subfloor. And I correct my earlier mistake, it is NOT T&G. 3) 3/4" fir T&G flooring but is covered with a layer of linoleum. When I am ready to remodel the room I will remove the linoleum. I had planned to lay 3/8" exterior grade plywood as an underlayment down on top of the 3/4" fir flooring, leaving all of my flooring intact. I will keep the bath where it is at the far end of the room (you can see the green pipe at the top of the pic). The size, either 5' or 5.5' depends on how the joist position turns out. I will move the sink to the Rt side, where the heating duct comes in. I will shorten that duct span to bring the vent closer to the front of the room (even closer to the top Rt hand corner of the pic). I will move the toilet a few feet towards the far end, about where you can now see the exiting sink plumbing on the left of the picture. I had plans to use self leveling compound and maybe imbed an electric floor/tile heating system ontop of the underlayment. This heating system is only for the tiles not to provide primary heat to the room. The room is ducted for forced air heat. Next, over the underlayment with self leveling compound (and possible heating system), lay Ditra. Then, as I understand it, I am ready to tile as per usual. As stated above I will be using 6x6 up to approx 12"x16" tiles randomly placed in the design. Bottom line is that I want a floor that will support my tile and fixtures in the BR. With all of the posts above it sounds like I need to do something, or nothing, to the floor joist system (except to get those hangers in there). I am leaning towards adding joist inbetween the existing one in the middle. The spaces between the exterior joists, sitting on the sills, and the 1st free spanned joists on either side, might be a problem because of the plumbing, especially on the left where the toilet is (out of sight in this pic). So I might have to leave that area without extra support. Or maybe I could brace around the toilet to stiffen up that area. While the Rt side might be tight, I still might be able to get a joist in there. Anyway, that is my current rendition, taking all of the above discussions into consideration. Any feedback on this plan? ps, this took me FOREVER to write up!

Build a chase from the ceiling to house the extra insulation. It would be like a drop down ceiling. This is assuming you have the 'head space' to pull this off. If your ceiling height is 9' tall now, dropping down 5.5" shouldn't be all too noticeable. If your ceiling height is 8' or less? Probably not a good idea. Realize when you drop the ceiling down, this will also drop down ceiling fixtures. Last thing you want is something for someone to bang their head on. By using bracing you could use regular 2x4 lumber to build the chase with. As this chase is merely to just house the insulation. The 2x4 lumber would follow same path as existing rafters, the insulation batts can then be stapled to the underneath side and then sheet rocked over after the batts have been installed. Any electrical for overhead lights can be run at the same time and new light fixture supports added to support the light fixture at the new lower drop down ceiling point. Once that is complete, sheet rock over the insulation that is attached to the 2x4 lumber used to build the chase with. So you need to make sure the chase is well built and can take the load of the sheet rock. (that would be it's only load, as this wouldn't be roof support or anything like that, IE don't cut into the existing roof supports --- add to it, do not take away.)