For the deck, my technique: Yes, for a "generic" installation you frame it, then use CDX ply on the top of the frame, then 15 lb felt on top of the ply, then use thinset and screws to set the cement board on top of the ply/felt. If you think you'll be getting a lot of water/splashing on the tub deck, you can treat the top surface of the cement board instead of using felt underneath the cement board. Use RedGard, Kerdi, or some other topical waterproofing to better protect the deck. You can also run the waterproofing up the walls a little bit. Here's where paths can diverge regarding tub installation. After the cement board is installed, some will install the tub and leave it shimmed high so that the deck tiles can be slipped under the tub's rim when the tiling is done at a later date. Others will tile the deck first, then drop the tub in on top of the tile. Some others even drop the tub in with the rim in contact with the cement board, then tile up to the edge of the tub rim, and caulk the gap. I prefer tiling the deck completely then dropping the tub in on top of the tile. You only put the mortar bed down at the moment when you are ready to set the tub. And remember, it's the base of the tub (mortar bed) that supports the tub, not the rim. You don't want the tub "hanging" from the rim. The mortar bed (or tub feet for a non-mortared installation) should support the tub with the rim just contacting the tile. After the tub is set you can make the plumbing connections, test for leaks, then tile the front apron. For a soaking tub there's generally no need to treat the adjacent walls unless you think your soaks will create the occasional tidal wave. If you're going to add a baseboard or trim piece where the tub deck meets the wall, you can fold the tar paper (or previously mentioned Kerdi or Redgard) up the wall a few inches and cover it with the trim piece. Some people also run a row of tile on the wall as a transition. Caulk the junction where the tub deck meets the wall trim or wall tile. There should be no need to remove and replace the existing wall board around a soaking tub installation. I do all the work myself, so I can control the work order and shift from one thing to another. If you're subbing out the tile, you might be better served by arranging things so your tiler can tile everything at once to minimize site visits and installation costs. In that case an access panel for the plumbing would help.

These are the ones I am familiar with: 1. Perm-A-Barrier VP î Air/Vapor Barrier fluid applied synthetic latex rubber membrane as manufactured by Grace Construction Products. a. Primary Air Barrier Membrane: One component elastomeric membrane, spray applied. 2. Air Bloc 31 as manufactured by Henry Company Inc., Cold Stream Road, Kimberton, PA 19442. 3. Sto Guard Assembly: manufactured by Sto Corp., Camp Creek Pkwy, Atlanta, GA 30331 a.Sto guard mesh for joints and flashings b.Sto Gold Fill for joint treatment. c.Sto Gold Coat for the membrane 4. PROSOCO R-GUARD Assembly: provided by PROSOCO, Inc., 3741 Greenway Circle, Lawrence, Kansas 66046. a.PROSOCO R-GUARD Tape for joints and flashings b.PROSOCO R-GUARD Fill for joint treatment c.PROSOCO R-GUARD Spray Wrap for the membrane I have used the WR Grace product on CMU back up in a brick cavity wall for a college dormitory but I like the STO system for residential construction because it can be applied by anyone with a roller.These products will someday be the only weather/air barriers used in houses when the manufacturers finally decide to actively market them for that use. Sorry, I don't have any cost data at the moment.

Here is my response to a similar question on one of the other boards. I reasearched this a lot, and though I'm not in a cold climate, most of the recommendations would hold for your situation: I had a similar situation. Some genius had put 3 inches of blown fiberglass in the attic (over the knob and tube wiring!) and that's it. The room was hot in the summer and cold in the winter. Here is what I did: - r13 on the floor between the soffits and the back of the kneewall - this was over conditioned space down below (I didn't cover it, but I could have if needed for storage)- rafter vents at the soffit-end of the insulation keep the soffits open - r13 kraft faced insulation on the back of the kneewalls (2x4 wall construction) - 2" isocyanate foam insulation (r14)with reflective surface on the angled portion of the ceiling, leaving 1.5" air space up to the unfinished part of the attic. My rafters were true 2"x6", so I didn't need the fancy channeled insulation. This insulation is R7 per inch, so I got R14 on the slanted portion. - R38 faced insulation in ceiling of the finished space, with eyebrow roof vents to keep air moving through there. - seal up all penetrations (electrical boxes, pipes, etc) with caulk or spray foam) The principles you need to follow are that you should insulate any of the unconditioned space where air from the outside is flowing. Any vapor barrier (e.g. the kraft facing)should face the INTERIOR - don't put insulation then vapor barrier, because then any moisture from the interior will reach the cooler air of the unconditioned space and condense, leading to mold. If you use the foam insulation, you have to cover it with a fire rated material (e.g. sheetrock). You could also consider using the new reflective sheets on the bottom of the roof sheathing - I didn't do this, but apparently it has a huge impact on heat gain. The impact - the upstairs is comfortable all year. It has no dedicated heat or AC, but never gets below 65 during the winter or above 72-73 in the summer. If it gets stuffy on the hottest days, I open a couple of windows to get a cross breeze. Hope that helps.

One of my concerns about putting a vapor barrier down on the dirt floors in my old house's cellar has to do with the risk of creating a super-saturated zone right at the foot of my dry-laid walls (some rubble, some much more carefully selected and laid, but all w/o more than chinking mortar.) The vapor barrier, in my view, is there to stop the inexorable rising of water vapor from the soil. (It rises due to constantly changing atmospheric pressures that no one can do anything about.) Blocking it at the cellar-floor surface level won't stop it rising, but it could channel it all outward to the edges of the barrier. If the barrier is tightly sealed to walls (as it ought to be) then where does all that accumulated water vapor go? It seems to me it will create a lot of sogginess in the soil at a very bad place: where the foundation of my house rests on what I assume was undisturbed soil at the time of construction c 1845-ish. I think it's important to differentiate between free water that comes in during periods of high soil water or the result of poor local drainage from roofs, flooding, etc, and moisture that comes from rising soil moisture vapor. The free water part may be containable, managable, or mitigated, but soil moisture vapor is probably not something you can stop. Moisture arising from the soil in very old houses may be a natural phenomenon that we have lately defined as a problem, or that has become problematic because of material changes we have made to our buildings by installing central heat, insulation, double-glazing and even running water. It may also be that our expectations have changed to cause something previously deemed "normal" to be seen as a problem in need of action to eliminate. Before there was electricity and air-conditioning technology I doubt that people were much pre-occupied with removal of air-borne humidity by dehumidification. But the fact that we can do it, may now make us feel that we have to do it. I also disagree with the notion that keeping cellar rooms closed up during the warm months is the best course of action. I do see the logic that keeping warm, summer, moisture-laden air away from the soil-cool stones of a foundation avoids condensation on the walls. But I am less concerned with condensation coming from warm-air atmospheric moisture, than with venting soil moisture vapor to the outside of my building envelope. Old people around here who lived in old houses like mine have told me of the careful attention they paid to opening up the cellar and airing it out after the winter. Since most of them lived and worked on the farms they were at home to attend to this and paid close attention to the direction of the wind so to maximise the flow-through pathways by opening different windows, doors, etc. I practise this as much as possible and it results in a dryer cellar, even though I still get some condensation on the walls, especially in the early Spring. In the years when I can pay the most attention to active cellar ventilation, my cellar - and consequently the rest of my first floor - stay the driest. But it often takes multiple changes during the course of a day, and I have to have my whole outdoor cellar stairway open all the time (during the day, it's generally closed at night to avoid dew-laden night air), which many people couldn't or wouldn't do out of fear of intruders. My cellar walls show evidence of multiple layers of white-wash (quick-lime and water). This is an effective preventive, curative and aesthetic disguise for dampish stones. It does nothing to reduce humidity in the air (adds to it for a few days as it dries off), but it makes the cellar seem less grungy. I struggle with this issue, a good deal, because I think a lot of the best-advice from old house "experts" may not be the best for the building's long-term survivabality. Info dump: My house is located in northern, NY. Foundation as described above, otherwise timberframed, two-story, wooden structure with its original plaster walls intact. Wall cavities are mostly filled with two separate layers of backplastering on wooden lath. Two layers of 5/4" X 10" T&G sheathing with clapboards nailed on top. Slate roof. Still no central heat, though now only two modern, more-effective stoves rather the original 4-6. Electrified (but not in every room) just before WW II; minimal indoor plumbing installed in 1960. In short, a oddly long-term survival of 19th technology, which I am slow to alter. If you're going to put vapor barrier down, and going to the trouble of sealing it properly, you should use material specifically intended for the purpose, not construction poly. I haven't solved this problem to my satisfaction, yet. Lately, I have been thinking that I should undertake a more active course of observation (recording indoor and outdoor temps, humidity and wind direction and speed) along with a program of trial openings and closing to gather better information to form a more thought-out moisture vapor reduction program. (I expect this was all empirically known a hundred years ago, but even old timers now have forgotten the details, alas.) This summer has been dryer than normal so perhaps this would be a propitious time to start. There is a guy, an engineer, (located in eastern MA, I think) who owns an old house and he has basically sealed up his entire cellar walls and floors from within. I'm drawing a blank on his name, but a frequent poster, Worthy, often posts links to his work so if you search for Worthy's posts on this forum you should turn up the link. I have read this guy's writing on his website, but remain unconvinced that it's what I should do with my old building. I don't think he's a crank, or anything - and he may be right - but what he does is essentially non-reversible. That irreversability is what's stopping me. L.