Bathroom Remodel/Retrofitting with Natural Materials

My girlfriend and I have been reading over this site for years now, but we've only recently moved in to a house in Detroit (see this thread for what sounds like a similar scenario). We have tons of projects to start on, the general direction being an attempt to move the house towards greater energy independence and efficiency, as well as comfort and coziness for ourselves. There's been a few threads over the years that have dealt with the fact that, realistically, most environmentally-minded folks don't have the ability (resources, skills, money, what-have-you) to actually design and build a new home from scratch. We too, fall into that category for the time being and need to alter and design this structure to function more effectively.

Trying to prioritize and see what can realistically be done in the midst of a relatively mild winter before the growing season hits, we're looking at first redoing our one small bathroom. It's a good place to start in the house because it lets us tackle a couple essential problems that are going to define how we move forward with other projects: How do we install better insulation and control air movement in the exterior walls? How can natural building materials/methods be integrated into a stick-frame house? How can we do this cost-effectively? (we don't count our own labor as much of a cost)

Currently there's an oversized tub that's been jammed into place with a few holes punched in the old plaster for the faucets and the shower head. There's a few inches of gap between the end of the plaster and tile and the edge of the tub where you can see into the studs, and the end of the tub (opposite the faucets) is pressing up against the studs of an exterior wall with tattered fiberglass insulation visible behind the metal lath. A stiff chill was wafting out of the cavity before we taped up a sheet of plastic. Besides just replacing the tub though, we also need to tear down a good part of the tile and some of the drywall to replace the current ventilation system--an ill-fitting, drafty window--with something more controlled and less of a heat loss. During this process we can also add better insulation.

There's no real water damage and the pipes are in good shape, and we have gone through the conventional process before; we understand how to do the job with some fiberglass, cement board and tiles. We've been surprised though, by how little information regarding natural bathroom building we've been able to find. Perhaps this makes sense. Given the heightened presence of water and air movement in a bathroom, maybe it's best not to dicky around too much with the conventional construction basics. But we're trying to find a better way, one worthy of this forum. The main consideration is: do we want our bathroom walls to "breathe" thus moving a certain amount of the interior moisture outside through a suitable insulation (potentially cellulose)? Or do we want to try and replicate the sealing effect of tile and grout, and simply better ventilate the space? Or maybe I've grossly misunderstood a key element?

We're perfectly happy to find an old tub (even a freestanding one and redo the floor underneath) to fit the space, but we need to properly redo the walls and floor. Perhaps we could do away with the tub entirely and build a shower space with a material like mortared stones that slope down to the drain?

In other parts of the house we have considered adding infill such as cordwood or cob-plastered straw bales but we're concerned that certain natural building materials like cob might not work in a high-moisture environment like this. Would these materials be useable if we simply increased the ventilation? I don't think we have the money or skill to build extensively with lime-plaster. Could another form of earthen plaster work if we protected the areas in direct contact with water with tile or stone?

Instead of a solid infill, we had considered blowing in cellulose as insulation, and even extending the wall gap by tying 2x4's to the existing studs to increase the insulation's thickness. We've also looked at installing batts of rockwool. But insulation materials that don't also act as an internal surface in the bathroom still need to be covered though and again, we're at a temporary loss on something with which to replace cement board and tile. Perhaps we should just find a happy medium between natural and conventional materials; putting up lath just for the sake of using earthen plaster doesn't necessarily seem like a worthwhile endeavor.

For the window we're currently looking at using glass blocks (readily available in abandoned building in the area) with some kind of vent or fan integrated into the blocks. The view is hardly worth having, nor can we do much with solar gain. Even though it's on the south side of the house, there's only a narrow strip of sidewalk between us and the neighboring house. If some kind of natural material like cordwood could be used then perhaps we could use the common trick of adding in glass bottles for light infiltration and then installing a separate mechanical ventilation system?

In short, does anyone have thoughts or suggestions regarding the materials we could use to refinish the bathroom? Hopefully you all will have some ideas on at least where we can look to better understand how to proceed. In the past these sorts of discussions on other people's building considerations were really thought-provoking for me, so if nothing else I hope this provides further discussion on retrofitting existing homes. It's only going to become more and more important as more people begin looking at ways to integrate their homes with their surroundings and their lives.

HEY Kieran...big welcome to Permies.com...!!

This is a great...really Great...question and project...natural bathroom...Yay!

There isn't enough info on this subject or "wet spaces" in general when it comes to natural building modalities...Your keen for taking note of that.... I was even kidding (a little) with my business partner that I could right a book on this subject alone and it would probably be more successful than the one I am planning for "Timber Framing."

Before I can really get into your questions, in good conscious as a facilitator of natural and traditional building, I have a few questions and requests.

1. Photos of the entire bathroom space.

2. Floor plan sketch of the house including yard and cardinal directions noted. This includes known stud size and spacing, over all structural outlay, basement configuration etc...

3. Circa date of architecture.

Thanks in advance for those things requested above.

I think most of your plans are very doable...at least 90% of them...There is no reason that this project can't be almost 100% natural in...means, methods, and materials. Even a nice Japanese Bath theme (one of my specialties) is very achievable...

Look forward to being of service...and again...Welcome!

j

Hey Jay, thanks a lot for your response. I've read through several of your write-ups, particularly those with regard to different foundation construction methods across cultural/traditional methods and have a great appreciation for the insight you have to offer. Due to the ease of doing this on the fly I'm going to respond to your questions in reverse:

3. The house was built in 1953. I don't know enough about the evolution of American construction to name an architectural style associated with but I can describe it. It's a closed floor plan (something we're hoping to eventually open up to better spread heat from our wood stove, replacing walls with half walls that provide greater thermal mass) over a crawlspace foundation. The crawlspace has poorly-installed fiberglass insulation under the floor joists, but it's relatively moisture-free. There's an almost-square hip roof with a slight ridge going east-to-west at the peak.

2. Floorplan will be attached in the following reply

1. Here's three pictures, the bathroom is small so there's not too much to be shown. The tub and back wall are the first places we need to get fixed up because of the lack of insulation and the draft coming from the exterior wall.

We've been reading through several methods of laying floors and walls with natural materials in saunas/bathhouses/showers/etc., but many of them rely upon an earthen foundation underneath in the Japanese vernacular you use I guess it would be kind of like a doma (sorry I don't know the character for that one). One example would be of a gravel subfloor with insulation above, sand on top of that and eventually stone tiles and grout. A big gap in my building knowledge is whether or not some variation on that method would be possible over a crawlspace foundation. Based on your work--which if I've understood correctly often employs a takayuka (高床) method--you clearly have a method for doing natural building on a raised floor. We look forward to your ideas.

-kieran

Here's a floorplan of the house. We don't have any official blueprints so this is a plan we drew up for our own benefit, though I'd be lying if I said if it were exact exact. I don't have any experience with Google Sketchup or other building design programs so this is hand drawn. One square block is 1 square foot and the walls are roughly 6 inches wide. Studs are 16 inches on center. Per your request I've added a compass rose. Note, however, that there is another 1-story house only a few feet to the south of ours, so any passive solar gain is minimal at best.

*edit: I'll add also that while the floor of the bathroom is some kind of linoleum, under the tub it goes down another inch or so straight to the subfloor, which is just plywood. Kindly neighbors in the area have already offered their bathroom facilities during our construction phase so we're considering tearing up even more than is strictly necessary, and trying to really make the bathroom a pleasant space.

Wow, that's the worst tub change out that I have ever seen!

It sounds like you are on a budget, so I would avoid tearing down too much unless you know plumbing. Bathrooms have complicated drains and it can be difficult to change them without significantly altering the main drains. This may not be the case, without seeing it I can't say.

Take the little wall in front of the tub out and remove the tub. Install a normal steel or cast iron tub that you find second hand. Remove the damaged tiles by lightly tapping on the interface of the mortar and wall with a cold chisel. Replace tile backer as necessary and re-tile. Yeah this is not natural building, but throwing away things that work is not that great either.

Now strip of all that nasty latex paint. I use steam on all but the most stubborn paints. Once that is gone we can start to build up a natural breathable plaster. Gypsum is a great plaster that often gets overlooked, because that is what drywall is made from. It is still a great natural mineral plaster. I like to then apply a lime wash or light plaster over the gypsum to make it more durable.

If you want to go deeper into this, just ask the questions.

I have attached a photo of my daughter's bathroom that was in similar shape. Lime plaster(tadelakt) over gypsum and drywall.

Hey Bill, thanks for your input. While researching, we've looked into lime and/or gypsum plaster as you mentioned, and currently we were thinking that that was going to be our method for redoing the walls around the outside of the tub. I had come across tadelakt as well, but it seemed like something best saved for another project and another house when I have more experience with lime and earthen plasters.

I do indeed want to go deeper! And so I will ask the questions.

You bring up a good point, that "throwing away things that work is not that great either." The tile and plaster that's currently on the wall is obviously functional and so our simplest solution would just be to replace the backer and replace broken tile around a well-fitting tub, as you rightfully pointed out. However despite working on a budget, we'd like to improve the space, as right now it's not particularly... well it's not anything, it's just a shitty bathroom. The bare-bones repair would render it "finished" but there still wouldn't be much of a sense of space or enjoyment of that space.

So assuming we want to do more significant renovations I will try to provide some further information. The water pipes come into our crawlspace almost directly below the sink in the bathroom. The drain to the tub goes down through the subfloor and hooks up in the crawlspace. I have been told by a neighbor with PEX tools to replace the PVC pipes with PEX, but I haven't seen a clear reason to do that yet as we have no plan to alter the plumbing scheme. You seemed like you were partially advocating for less tearing-down because of plumbing risks, but we don't intend to alter the floor plan or general bathroom setup in any way.

What we do want to do (in order from practical to aesthetic) is: fix the exterior wall to stop the air flow, replace insulation in the exterior wall; replace the leaky, non-private window; add flooring under the tub if we can find a freestanding tub; and refinish the walls (maybe also flooring). We have about a month before the pressures of the growing season begin to restrict our construction time.

All of the tile that's currently around the bathroom was laid over plaster and metal lath, by getting under the tub and looking up into the exterior wall I can get a pretty good view of it and the insulation behind, which is all smooshed and smashed fiberglass. It seems to me that it might be a worthwhile use of our time to replace that fiberglass with something better. Obviously that doesn't absolutely necessitate pulling down the tile to do, but it would make it easier to replace the fiberglass with a dense-blown cellulose. Personally I would prefer to try and use some kind of natural insulation like light straw-clay, but because are studs are only 2x4's I don't see how we could get the necessary thickness to approximate a similar R-value without seriously encroaching on the tub space. We could replace the tub with a shower, or we could remove the shower head and use just a tub. Over time we should be able to install an outdoor shower for use in the warmer months.

One benefit to removing the shower head is that we'd then be able to finish the walls with a much greater variety of materials as they would not be taking direct water contact. Lime plaster around the entire bathtub alcove would become possible without going into the in-depth process of tadelakt. Do you have any opinion on that idea? If we do remove all of the tiles (I just took off the majority of the broken ones this morning and without too much effort), it might not be worth it to put up a whole series of new ones. Instead we could do anything from lime plaster to wood (maybe?) and the material would not be exposed to direct water.

If you think the process of replacing the insulation is unnecessary because we will already be gaining greater warmth simply by stopping the exterior air movement, do you think it would be feasible to remove the tile from the plaster and then simply use the metal lath and remaining plaster as a surface to lay new lime plaster over? That could greatly reduce our work time because the lath would stay in place. If we still wanted to add insulation, we could also then cut a few holes in the drywall above the tile and blow in cellulose ourselves, though I fear the loose fill in a bathroom would shift over time as vapor entered and exited the wall. We also will eventually have to redo the exterior wall of the utility room and we could just continue over and redo the insulation from the outside.

Currently there is neither plaster, nor lath, nor tile in the hole around the faucet. Assuming we don't go the cement board route and want to do plaster there, Hhw would you recommend we have the faucet come through the plaster? Would it be wise to do at least some kind of tile backsplash right around the faucet and handles?

Because of the nasty view outside the window, and it's poor fit/general draftiness, we were looking to replace it with glass blocks. I'd appreciate thoughts you might have on that, or better ideas.

Lastly, what are your thoughts on the floor? The bathroom picture you attached didn't show the flooring. But I'm open to suggestions.

Thanks again, working through some of the ideas "out loud" helps me better weigh the factors that affect the end decision.

Well alrighty then! It sounds like you are ready for demo. I like to provide easy options first and see where you are at. That way I don't just go off on some tangent.

First we get rid of the toilet(when you do this, plug the hole with a test plug to stop the sewer gasses from coming in), sink, tile, tub and the lath surrounding the tub which is actually drypack cement, not plaster. This is an OPC(ordinary portland cement)/sand mix that is packed into the lath in a dryish mix so it can be perfectly leveled. This is how they prepped a wall for tile before cement board. Turn off the water and disassemble the plumbing. Either take it down to a threaded fitting and plug that or cut the pvc and glue on caps. Most of your pipes are probably galvanized steel, which is where the pvc will be threaded in. PVC makes the worst water pipes available. I use copper for drinking lines and pex for all else since it is so easy. Next strip the floor down to the subfloor and tear out the dividing wall for the plumbing of the tub. This wall is unnecessary since you are going with either a free-standing tub which will be filled from either the side or from a faucet mounted on the tub supplied by lines coming through the floor or a walk-in shower. Remove and save window trim and remove drywall from exterior wall.

Now you must decide on the final layout; basically tub or shower. I'm thinking tub since it will be much less work and require much less skill. Find an old clawfoot, then refinish with Abatron porcelain restorer and paint the bottom exposed area with automotive or DTM(direct to metal) paint. A lot of times these tubs have a faucet attached, these can easily be rebuilt.

For insulation, I like rock wool. A 2x4 wall insulated with rock wool is only R-15; not good enough for your climate, so I would add furring strips to the studs to make them at least 5 1/2 inches deep which gets you to an acceptable R-24.

If you want to plaster with lime, you will need to prepare the putty. There are many very nice limes out there, but they are somewhat expensive if you have to ship very far. I have a hard time getting the better limes, so I usually use the stuff from my local building supply; type s hydrated lime. It sells for $10 a bag and even the big boxes carry it. I use 3 5-gallon buckets per bag; you will probably only need 1 bag. For this you need a large drill and a mixing paddle. Pour water in the buckets 1/3 full, then add lime 1 bucket at a time 1/3 each and mix well. Then add a little water to cover the putty and cover the top of the bucket with a plastic shopping bag(they fit over the top perfectly). Age your putty for at least 10 days.

This will get you going for now. Ask more questions and I and others will do our best to answer them.

Bill, thank you so much for that breakdown. I had already started whacking off tiles last night; the tub makes a nice receptacle for the mess. We went to the store today and bought lime as well as some sand for the eventual plaster. Tonight we'll be mixing up the lime putty and leaving it to age(/slake?) for a while. A couple preliminary questions: You said "tear out the dividing wall for the plumbing of the tub." If you look at a our (poorly-labeled, roughly-drawn) floor plan, there's actually a closet on the other side of that dividing wall that's rather useful, so I'm probably going to leave that in place. Unfortunately this limits the size of the tub we can put in, which forces us to be a bit pickier. It might also make it difficult for us to deepen the wall cavity of the exterior wall since the tub will be in the way. The position of the tub in the bathroom is pretty much fixed, because I don't have the technical know-how to relocate the toilet... We've got a bead on a couple of tubs though, and at least one should fit the space.

Appreciate your insight on what I thought was plaster and is actually drypack cement. That makes a lot more sense because it was sustaining very little damage as I was knocking the tiles loose.

My main question right now is: what surface should apply the lime to? Especially on the exterior walls where we're going to have to place something over the rockwool insulation. Do you suggest we build a kind of lath?

I've also recently come into some wood planks (Detroit's the scrap capital of the world). Would those be useable on the interior walls for all or part of the wall? They'd be similar to the lime plaster in that they'd accept and release a certain amount of water vapor without being exposed to direct water. If they are useable, can I place them directly over the studs? I was looking it up to see if that was allowable by code, but I couldn't figure it out. Obviously for the exterior wall I'm still going to need to use plaster in order to form a proper air seal. What are your thoughts?

I also took a whack and pulling up some of the concrete/tile flooring that currently covers 2/3 of the bathroom. It's got the nice expanded metal mesh laid onto the plywood subfloor for added fun in removing. My plan is to redo this with a clay plaster an inch or two thick and then either finish that or tile over it. My understanding is that concrete is about 150lbs per cubic foot. The clay-sand mixture I would use would be a good deal lighter so I don't foresee any problems, should I be concerned about adhesion though? I've heard tell of cob not sticking well to timber framing, but friends of mine have done clay plaster as well as cob over wood with good results.

Jay, if you're still following along I'm curious if you could offer some insight into how traditional builders would have put down flooring on a raised foundation like this? Particularly in a cold, wet climate. I'm curious how you do it today as well.

Even though it's outside the scope of this project, I'm also curious how one would go about finishing the ceiling below the attic without the use of something like drywall and still produce a solid air barrier

This entire process is an interesting philosophical dilemma for me. We have a house with a ton of embodied energy in it, and most of its systems at least function, even if they're not finished. I constantly strive to reduce my impact on the planet's resources, insofar as I try not to senselessly remove things from the general decay-rebirth cycle by chucking them in a landfill. But we're now spending our own physical energy, and buying off-site supplies like lime, to remove embodied energy from the home and then replace it. I've decided that ultimately the benefit we're gaining by increasing our own knowledge of construction and natural materials is an outcome that outweighs the cost of these efforts. And to that extent we've decided that it's our responsibility to replace the current systems and materials with as much natural, recycled, low-impact material as possible. A good ideal to hold in mind I suppose when I find myself putting up wooden lath and plaster in place of drywall.

Yes, it's always tough to decide where the line is; rip it all out and go full natural, but throw a lot of materials in the dump or fix what you got even if it's not to your taste. I find myself walking the middle path; not really natural building, but not business as usual. I utilize industrial products , but I try to minimize the amount and as much as is practical, I use local natural products.

Every stone, tree, bush, even grain of sand wants to remain in it's current state right where it is. The only way to build in harmony with nature is to beguile each and every one with your eloquence and beautiful offerings so that they want to be part of the beauty that you are making. Anything less than this is modern means and methods. A bag of lime is industrial, but limestone that wants to be lime, cooked in a kiln that is built with materials that want to be utilized and cooked with wood from trees that happily gave up their natural existence because of your beautiful insistence, this is natural building the way our ancient and even a few not so ancient ancestors practiced it.

If you dig your own plaster with the attitude of; it's just here for the taking, then you may as well have just bought a bag from the store.

That poor, insulted store bought bag of lime, can still be elevated if you put in the energy to fill the hole ripped in the fabric of the natural world.

Past this, I try and use materials that get stronger and more durable with time. This is why I love lime. The plaster just gets stronger and stronger as the CaOH absorbs CO2 and becomes CaCO3 or limestone.

You asked about wood in a bathroom. My wife and I have a fir floor in our bathroom. Wood is amazing! Just don't use a film forming finish and it should be great. Even a natural film finish like shellac will be problematic, just use a good oil and if you want a light coating of wax. For air sealing use a building paper behind the wood and seal it to the surrounding walls with a high quality silicone caulk.

Lime plaster adheres really well to rough wooden lath, but not so well to smooth modern wooden materials. So the lath is attached to the wood and the plaster is stuck into the lath. Expanded metal works fine and lasts about 100 years or so, but wooden lath works better and lasts 1000. You can probably find literally tons of wood lath, free for the taking.

I'm horrible for skimming, so if I missed something feel free to bring it up again.

You continue to be a fount of quality information and reassurance, Bill. Good insights into the careful methods and thought processes we must go through to construct beautiful places.

Would you mind posting a picture of your bathroom floor? I'm interested to see how you did it. We were also thinking about using clay or lime plaster as opposed to building paper. Would that be applicable over the subfloor and then we could set wood into that? We were originally thinking about doing it with a mish-mash of tiles. It seems like the plaster should still function well as an air barrier. We had also been considering putting the wooden planks on the wall surrounding the tub. They're not tongue and groove so would you recommend putting up a coat of plaster first and then attaching the wood through that? Or just putting the wood up directly onto the studs? The latter option could only be done on the two interior walls as it wouldn't form an air barrier, and I'm afraid it could be a bit of a fire hazard since there'd be no plaster or gypsum board behind it (also probably not up to code...). Sorry if some of these questions are relatively elementary, I'm still learning a lot.

Thanks Kieran,
Yes, plaster is a very good option. It is breathable, durable, fire resistant and makes a great air barrier. If you start collecting lath now, you should have enough by the time the putty is ready. Just make sure the lath boards are still porous and not coated in latex or something.
Our bathroom's fir floor is the original T&G farm floor from 1890 when the home was built. I don't have any photos right now, but I could get you one.
Do you have access to a table saw? A simple "ship lap" can be created with only a few cuts or a groove can be cut in to accept a "free" tenon that locks the pieces together.
I think you are well on your way, post more photos as you go!
I've attached a photo of the back side of a 90 year old plaster wall in order to show the proper spacing and key or squeeze through.

So ordinarily, you would take great pains to protect wood in a bathroom environment. You have fir flooring that's been in there since 1890 though and I'm assuming it wasn't coated repeatedly in polyurethane.

How did they build it to last? I was considering putting wood on the floor since we have it available. But with the lime plaster I feel relatively confident that it will be able to take up and release moisture. I don't feel confident about the wood though. It would be installed over a 3/4" plywood subfloor over the crawlspace, but I can't figure out what steps to take to make it sure it can adequately dry out. For now we're leaving the leaky window in place to let the room stay ventilated and over time we'll figure out a better-controlled system.

The thing about films like polyurethane, or even natural film like shellac, is they blister when vapor from the interior of the board pushes it's way out. This blister pops, compromises the finish and more moisture intrudes until failure.

If you use a good oil, there is no film to push off. Think of oiling the skin on your hand, now stick your hand in water. It beads up; same thing with wood.

One way to preserve wood is to char it first to remove the sugars from the wood that mold likes to eat. Check out this thread Yaki-sugi

Here's a photo of a deck that I restored; it was about 14 years old when I planed off the "natural" film finish that was originally applied and oiled the bare wood. 10 years later it still looks great.

Before oiling a re-used board, first wash with oxy-clean. The stuff is amazing; I clean whole cedar roofs with it.

While I was looking for photos, I came across a bathroom remodel that we did a while back that is like yours. This is a 3 layer finish plaster to give depth to the tiny space. First grey clay, lime and gypsum, then straight lime, then lime with crushed azurite. We pretty much just changed the finish on the walls and installed new wood trim with oil finish.

I had trouble with the deck photo loading, so here it is.

While looking, I stumbled across this photo of a cafe remodel that we did in pine, with oil and shellac. The shelves and countertops are in birch plywood. The shellac is only for wear resistance, not waterproofing

Really wonderful pictures Bill. And that yaki-sugi thread was great. I'd heard of that method before, but hadn't really looked into it all that much. Your picture of the pergola shows a really cool and varied effect across the wood.

Apologies if I'm just rehashing the same question, but I don't think I've fully understood yet. Even if the wood is tongue-and-grooved or "shiplapped," it's still not going to create a full air barrier behind the boards, is that correct?

In the bathroom for example, I've been collecting T&G boards from houses scheduled for demolition which I will clean and then oil. That part makes sense to me. I'm going to place them over the plywood subfloor, and I'm wondering if I should put something else down between the boards and the plywood? I know I can put down #15 building paper, but I don't know if that will lessen the wood's ability to "breathe." I'm also asking more in terms of natural building", partially just out of curiosity. It's less of an issue on a concrete pad or earthen foundation, but when you're on a raised foundation of some sort, what do you use underneath the floorboards?

Thanks for walking me through this. I just want to make sure I understand all the elements and forces that are going to interact with a material before I install it.

The 90 year old home we are currently restoring had exactly that in the bathrooms - diagonally installed 1x sub-floor, 15# building paper and then fir t&g flooring nailed on top of that. You just nail the tongues. Much of that floor is still in good shape.

Don't worry so much about full air barrier; go after the drafts. The building paper will keep out the drafts and is vapor permeable. I don't however use it behind steel lath as is commonly done these days. It's not necessary as a good plaster job will provide the draft proof seal.

If you want to reduce your heat bills, go in the attic. Look at all the places air can escape into the attic from the walls and ceiling. Stuff these openings with rock wool insulation. I save every scrap from insulating for this purpose. Take a metal colander and set a votive candle on it, now cover the colander with an upside down metal bowl. The heat stays in. Put the colander on top and the heat escapes.

We actually went full bore and tore everything out of the bathroom. Leaky tubs and toilets had ended up causing lots of rot in the subfloor and even in some joists and the bottom plate of the exterior wall. We replaced most all of this which took longer than expected and was kind of cold while the bathroom was basically a giant hole down into the crawlspace. In retrospect we probably shouldn't have pulled the concrete floor off the subfloor, as we could have just floated a wood floor above that. But we did, and maybe it was for the bet because it exposed the extent of the damaged structural members underneath.

After demolition was finished though we went ahead and got ready to plaster. In case it's helpful to anyone else, we decided to go with a lime plaster because the bathroom is obviously a pretty moist environment and given that, we wanted something with sufficient moisture capacity (viz. the recent thread on breathable walls for much better insight into the specifics) to retain and release that vapor, while small enough pore space to resist any bulk water damage. Gypsum drywall is "breathable" enough that we probably didn't need to tear it down before applying plaster, but we're gluttons for punishment and wanted to work from scratch so we took everything but the ceiling down.

Holy cow is it hard to find comprehensive information about lime plaster preparation and installation. We cobbled together bits and pieces of information from a ton of resources: Mike Wye, Ty Mawr, and others. We actually put up wood lath using some rough cut scraps from a nearby sawmill that we usually pick up for kindling. Wetted that down and applied multiple coats of plaster in progressively smaller ratios of lime to sand. Our first coat was exceedingly sloppy because we had no idea what we were doing, but we moved up the learning curve pretty quick. In the final coat, we mixed in some boiled linseed oil and polished lightly with soap, but we then decided to apply a limewash over that because we found some cheap mineral pigment. Not sure if that was the best decision or if we should further polish/burnish the limewash, but so far we haven't experienced any problems. I highly recommend experimenting with plaster as putting it on is about as much fun as spreading butter on toast, which is to say, a lot. At least when it is working well.

For aesthetic reasons we put up kind of a puzzle/collage of randomly sized wood planks on the wall behind the tub. And given that our floor is suspended over a crawlspace, we followed one of Bill's many helpful suggestions to just use building paper (red rosin in our case) with shiplapped 2x10's for the floor. I pulled those out of the rafters of an abandoned school where they had been hanging nice and dry since the 1920s. They creak a little because I'm not a much better floorwright than I am a plasterer, but I appreciate their groans after a long life as collar ties.

One decision on which I am still not confident was my decision to "float" the floorboards. After we redid the subfloor and laid down the building paper, I laid out the floorboards and felt that they were too cold. By chance the drain pipe for the toilet was also too high. I was (and still am) not fully convinced of the efficacy of all our decisions and was worried about screwing everything down permanently. Though there are probably a variety of solutions to these problems, I didn't feel like cutting the cast iron closet bend and I didn't want to install insulation in the bays between the floor joists. So we chose to lay some old 1xs across the floor perpendicular to the top floor, and then laid down thin batts of rockwool insulation in between. Despite probably only adding an R-value of 3 or 4, this made a perceptible (though hardly a miraculous) improvement on the floorboards ability to stay comfortable underfoot. I also left a small expansion gap behind the tub under the molding for the boards to shift if they so choose. If everything seems to be going well perhaps I'll screw everything down someday, but I at least have an easy out if we ever have to take things up for any reason.

Note that in the last picture we have a half-installed normal toilet as well as our gerry-rigged composting toilet chair in the foreground. Originally we were just going to put a rug over the old closet bend hole, plug it up and bid good day to the municipal sewer system, but our composting facilities in the yard are maybe not yet well-enough designed to take 5 gallon buckets worth of humanure every week so we're still shittin down a drain. I have an eventual plan for a compost pile ringed by a "tree bog" that is specifically for humanure, but I have to find a willow to take cuttings from first.

I'd also like to replace our sink and window. But we could only remodel what we had money for. If anyone has suggestions for replacing a leaky window on the cheap side without doing too much extra work I would be happy to hear it. Right now I've been playing with the idea of mortaring in a bunch of recycled glass blocks or bottles to make a more private window, but I don't know how well the mortar, be it lime or something else, would stick to the 2x4 window frame. Thoughts?

Hope this is helpful to any future permies bathroom redoers. It's not all permaculture all the time, but we try and view our building decisions through a holistic lens and make what compromises we must and move forward a few small steps at a time.

best,
Kieran

ah, forgot to mention above. lots of linseed oil on the plank wall and the floor boards. After a few days I sprinkled water hither and yon to analyze it's behavior. Felt good to see it bead up and stay in place to get wiped up by a towel. We went with Boiled (aka supremely jiggered with the addition of metal oxide catalysts to accelerate drying) Linseed Oil as opposed to raw because we couldn't find any for a reasonable price locally, and because we were kind of sick of pooping in the bedroom so we got impatient.

Here's another bad photo of our plank wall. If you think about it for more than 5 seconds, you might come to the conclusion that putting the wood right next to the bathtub was a bad idea. Possibly. We did so because we got to install fun shelves and hooks, and I'm hoping that the linseed oil combined with the woods ability to "breathe" a certain amount of vapor will not produce massive failure. Again, like the floor, if we have a problem here we'll disassemble the tub drain, remove the wall and reconsider. For now things seem nice though.

Hi Kieran,

Really, really great!!!

I love what you've done!

You've improved the aesthetic and function of your bathroom far beyond what your average contractor would've done with a bare minimum of materials.

Your PVC window can be replaced with a free wooden window, here's a thread Free-windows

Kieran Chapman wrote:ah, forgot to mention above. lots of linseed oil on the plank wall and the floor boards. After a few days I sprinkled water hither and yon to analyze it's behavior. Felt good to see it bead up and stay in place to get wiped up by a towel. We went with Boiled (aka supremely jiggered with the addition of metal oxide catalysts to accelerate drying) Linseed Oil as opposed to raw because we couldn't find any for a reasonable price locally, and because we were kind of sick of pooping in the bedroom so we got impatient.

Here's another bad photo of our plank wall. If you think about it for more than 5 seconds, you might come to the conclusion that putting the wood right next to the bathtub was a bad idea. Possibly. We did so because we got to install fun shelves and hooks, and I'm hoping that the linseed oil combined with the woods ability to "breathe" a certain amount of vapor will not produce massive failure. Again, like the floor, if we have a problem here we'll disassemble the tub drain, remove the wall and reconsider. For now things seem nice though.

Breathability is extremely important, as it affects the woods ability to dry when wetted. If the wood can dry within 48 hrs, there is no danger of rot or mold. The finish you have chosen will perform well for decades with no issues whatsoever.

Yep, looks good and like you got some good advice. If you are concerned about the wood get a moisture scanner and check it periodically. From what I read 19 and 28% are the ones to remember. below 19% is considered "dry" above 28% "fiber saturated" and many materials even clays get to this point and can not air dry, other than by drainage if they are open at the right pore size....we have data on the "Breathable Walls" although the rates seems to be hard to quantify like EMC (Equilibrium Moisture Content, based on RH) you measure with a scanner. I agree with Bill, with all that hygroscopic mass surrounding the wood I be surprised if you have issues. It will start to check (open, cracks) when it is saturated now becoming capillary more open. Across the grain as you have it is less absorbent/desorbent (like logs) than along and some seal up the end grain I have read anyway.

It appears a holistic approach with natural ventilation when showering is all that is needed cutting energy cost of running exhaust fans and air conditioners just by using better breathable materials that store moisture, imagine that!

Being the tech I am it been interesting to get some RH, MC, and dew temps before and after.

Kieran

Amazing effort. Hat's off to you for some major work getting up a plaster wall.

In Terry's thread I mentioned using linoleum on the floor. That's because baths and kitchens have _lots_ of water on the floors occasionally and some times quite a bit regularly; it's way better if that water stays in the bathroom instead of flowing "downstairs". Properly installed concrete, tile or linoleum floors keep solid water out of your floor structure better than just about anything. It's trivially easy for water from full tubs and regular showers to sneak over the edge and onto the floor and along the edge and down the seams into your floor. It's often very hard to see what's happening and because of that w/the wrong usage patterns a quart or so a day can make it's way into the house w/out you seeing it at all. That's not something a house will survive well, not matter what it's made of or how much breathing it does. If you expect your floor to handle solid water regularly than you should put in a drain on a tight floor. The moral is make it hard for solid water to get into your structure; if you make tight seams and seal them well along the tub (if built in) and walls/floor you'll be able to "catch it in the act" because it will puddle and you have a chance to notice what's happening. The above description is why I think you should pay close attention to what's happening _under_ the floor you laid on top. Even if it all just runs into the crawl space you may end up growing things if it gets rewetted every day.

But putting up a plaster wall first go from scratch, that's something! Carry on. <g>



Cheers

Rufus

I think you made the right move to go with all lime plaster, it is more hygroscopic that gypsum especially if the drywall glued on paper is not removed. Linseed oil has little effect on lime cement plaster (EG: Type S hydrated, or NHLs), here is what Strabe test show,

“The linseed oil had little effect on the permeance of either the 1:1:6 (cement:lime:sand) or 1:2:9 mixes. The latex paint reduced the permeance of the 1:1:6 mix to about 200 metric perms (almost 4 US perms) as expected. The oil paint also performed as expected, lowering the permeance of a 1:1:6 mix to around 40”

: http://www.ecobuildnetwork.org/images/PDFfiles/Straw_Bale_Test_Downloads/moisture-properties_of_plaster_and_stucco_for_strawbale_buildings_straube_2003.pdf

Bill attesting to having a wood floor in his bathroom doing fine now for if I remember right twenty years I'll take as empirical data difficult to debate, I think he said above he uses fir which is known for its weight-to-strength ratio, not as moisture resistance as western red cedar, white cedar being the highest. Bill has a lot of history as a remodeler. The history of saunas with wood floors is more, using soft woods that stay cooler on the feet.

Take a look at spruce in the graph below, note how even the curve is sloping up meaning a nice even spike in absorbing liquid water or vapor. Ironically, temperature has little effect on its ability to store and release it. At the end of the curve is where saturation or surface condensation occurs, you see spruce does not easily, plywood and other do after 80% RH. Concrete and stucco are slow to absorb/desorb (noted by the flat cure until 60% RH) then large saturation spikes noted by more tick marks on the curve, back to slow drying when the RH drops below 60. These materials will not dry fast in a 48 hour time frame and are prone to mold (from add mixes mainly), which in the germination stage cannot be seen with naked eye and can become air borne causing respiratory problems. Zero-to-low perm barriers on the floor from glued down linoleum, etc, could potentially trap moisture at the glue line, condense fast like glass. Take a look at this popular MSDS for the glues below, which is for the workers, not homeowners and will not list the installation hazards. Since we do not see that this polymer is stable or inert in the presence of moisture listed anywhere we can assume it is a fungi food since the MSDS does not specify it as fungi resistant. Be careful of manufactures not listing the assembly specs, only the natural details.

So if the crawl space is not maintained at a RH higher than the bathroom (can reach 100 when showing) and the floor is vapor impermeable, we have a good potential for fungi at the glue line from vapor uptake especially in low ventilation hot humid Crawl Space (CS). If the bathroom fan is used, or a drafty window open, that lowers the vapor pressure in the bathroom, and the crawl space has low air flow which a lot do, the bathroom will suck ground gases and moisture up into the bathroom and once again accumulate moisture on the glue it cannot get past. Small holes (likely) in a vapor barrier produce large pressure differences. If the floor can breathe in both directions at the slow rates discussed in my thread, and pass heat slowly to dry out any vapor that accumulates on any surface in combination with the breathable wall materials, inert anti-fungi materials such as wood and rock insulation, lime, the mold will not be able to grow. The breathable floors ability to equalize vapor pressures aids in this by not creating a high pressure differential across the barrier. It would have been a good idea to put a clay plaster layer on the old plywood, back then they used more formaldehydes (fungi foods) we do not today, phenolic resin (plastic) resigns and catalyst, oils for resign flow, and they do not mineralize the wood.....that would have neutralized or mineralized the wood sugars and in the same respect petrified wood is buried in soil that last forever, or other low density fiber-board makers do...If you look at wood in its natural habitat, despite seeing lots of water and moisture, the average life cycle is 50 years, western red cedar 150. In the average home, 25. You did right with the mineral wool insulation and keeping the wood surface dew temp lower than latent air, that should also aid in evaporation. The biggest concern is the plywood subfloor in winter when the CS is sealed and there is little vapor drive that direction to evaporate. If you tightly fit that mineral wool between the 1xs (great thing about MWool is the tight fit) it is inert and has some small moisture content, it also has a high surface capillary ability(like all rock) to hold liquid water spread it on its surface and evaporate it, water that drips down between the floor boards. That is why it in board form is rated for below grade, and is used as “drain board” so is wood fiber-cement boards rated for soil contact and below grade, and is a "capillary break" to wood.

MSDS: http://www.armstrong.com/pdbupimages/198079.pdf

I wouldn't even give it a second thought surrounding wood plants in a hemprete or strawcrete, clay-chip insulation between floor joist, sealed with a lime or magnesium binder or board. Red or white cedar or fur or pine.

Normally in your climate zone 2 x 4 insulation levels r-19 or 23 is not enough for an exterior wall, but the mass effect should increase that a good r-5 in r value terms. Plus the mineral wool does not loose r-value like FG or cellulose if it gets wet. It is also inert, needing no fire retardants.

I’d stay with all copper/brass fittings on potable water, it is 99% pure and use a lead free solder and ground it per code. That will reduce dissimilar metal galvanic corrosion that even occurs when PEX is used with metal or any plastic or rubber fittings. The additives in PEX have to watch they can leach into the water stream and each manufacture has their own and process. Any exposure to sun cause a chemical break down since there are no UV’s. CA has started to mandate UV protection for transportation, it can happen in the back of a truck on the way to the jobsite.

Well time to hit the road back to my out of state job site where it has been snowing all weekend. We got some fir timbers delivered yesterday...They linseed oil the inner, leave the outer bare. It and all the other wood has been seeing ALOT of water and moisture.....This place will build in moisture and the SIP barriers, glues, caulks, etc, they choose will not allow it dry out. A mold factory assembly line. Jay says they should be aged there, these are kiln dried down below 20% MC. They have to be above 28% now and saturated, along with all the other wood we have in the field...I told them to get the OSB tongue and groove out of the weather or it will swell.

Here are some Douglas Fir Timbers kiln dried coated with boiled linseed oil at a job site with a dew point of 42F, 70% Relative Humidity, 51 F temp. You can see some absorption. Along the grain where the pores are like straw will absorb the most, across the grain little as seen by the beads that are not evaporating since the temp is only 10F above due and the RH is high. Most materials RH above 80 is the concern if drying does not occur in 48 hours and a mold food source exist. In a heated (~70F) and/or vented breathable space this is not an issue, it should evaporate. You can see the stack the timbers on wood spacers for this reason, to not trap moisture. All wood at a job site should be stacked this way.