Shed style tiny house (not THOW) please help me avoid reinventing the wheel/tell me what you learned

Please dream with me then help me be practical, too ;)

The context is Mediterranean in the  mountains about 5km from the coast. My in-laws own the land and house we're renting (for at least the next six years when our twins finish high school). They had the existing 3bdrm house in the 1980s. I've been married to Jordi and living near Barcelona for the last twelve years so I think it'll be a yes about building on their property. If it's no, I might buy a vacant lot down the street haha!)  We have hot dry summers, and colder damper winters (typically ranges between 6 to 29 degrees C or 40 and 85 degrees F, seasonally).

I can build an outbuilding without special permitting permission in Cubelles, Catalunya (Spain) as long as it doesn't exceed 20 square meters (about 215 square feet) including the roof overhangs.

The site is on the third terrace level of the land with road access at the street level only (so not THOW). It's shaded a little by pines on the neighboring vacant lot and is on clay soil that's been pushed down from higher on the hillside. (There's gotta be bedrock too though because the existing house is on this level). It's fairly sheltered by the shape of the mountain, but still windy. We're below (a poorly-maintained but decent) fire break to the south with a prettyish wooded vacant lot to the east. The residential view (road, neighbors, our garage/workshop etc.) is to the north and the existing house is to the west of the site. The house's kitchen window will look toward the shed. The house entrance and front porch are on that side, too. The west wall should have clerestory windows high enough to give privacy to the bathroom and bedroom that will be on that side of the shed. I'd like the high side (3m or about 10f) of the sloped shed to face the green view east and the low side (2.75m or about 9ft) to face the existing house/outdoor living patio to the west. The opposite orientation of the slope might work better for bringing high wind up and over the shed (and indirectly the house) but I'd like more privacy toward the existing house and more spaciousness, windows and view toward green.

I have a spot next to the house where a basic 4m by 5m rectangle would fit with sufficient setback from the property line to have a little edge garden and not crowd the existing house too much. There's a bbq on the side of the house between it and the site, some firewood storage, and an outdoor seating area under a pergola. (My brother in law Enric sloped paving to direct water off the mountain and down the drain under this outdoor living area; I'd like to capture water off my shed roof and the house instead but if I do angle a shedroof this direction it shouldn't threaten undermining the house.)  The shed site isn't paved.

I would like to have it on piers since the footprint is pretty small and I think too much of the land is paved or rocked in already. Sometimes I'm tempted to buy a kit, but then you still need to create the foundation and fit it out. I have my own ideas about window and door placement that make them not quite right. If it gets plumbed with a small bathroom (short soaking tub, toilet, small sink, medicine cabinet, pocket or barn door) it should be in the northwest corner to be closest to existing sewer infrastructure according to Enric. Maybe a minisplit or airexchanger goes in the bathroom? There should be at least one (frosted or reacheable but high up operable) window in there too. Clerestory or transom windows are cheaper and less risky for leaking than skylights in my opinion. They're likely to be whereever I can fit them into the design.

I think a front entrance makes sense on the north side (same as house) with a small linear kitchen on the northeast wall (a couple of open storage shelves, fruit bowl and a cutting board, deep rectangular sink below an operable window, one tea/snack cabinet, a silverware drawer below it, good outlets for an electric kettle/plug-in hob/charging station. I would extend the countertop to be an eating bar facing another window toward the green view to the east so that it could potentially double as a workspace, too. (The 40+ years of kitchen crap that came with the existing house can be borrowed but I want only my Polish tea pot and mugs, one pot, one pan, with the lid that matches them both, four salad plates, four bowls, one salad bowl, one serving bowl, two good knives, silicon spatulas and silverware for four with a triple supply of spoons.) I can do 'real' cooking in the house as needed. I have something more like an office kitchen in mind. A door with glass, simple egress or a slider, goes in the southeast corner of the shed and the counter length is designed around what space remains accommodating the door/howevermuch counter length you can get with a single continuous piece.

The south wall is blank except for a clerestory window(s). There's a rock face of the mountain outside in that direction. (That sounds pretty but it isn't. It's just kind of brown and clay-y with chuncky rocks.) Bookshelves or art might go here behind my one comfy chair and the nightstand by the bed in the southwest corner. It's basically left flexible to change my mind about bed position or nightstand vs. desk or to sort out storage if someone ever really lives in it. Maybe there's a closet abutting the bathroom wall in the bed zone, maybe a narrow desk goes there, maybe nothing. I'll have to see how the space feels. The bathroom walls should create enough of a sense of separation that you don't see the bed the minute you walk in, but really it's a one-person space so the rest remains open. I have a rigid heddle loom that might go here instead of the comfy chair. Some dreary days I think it should be exercise equipment. You get the drift. The west wall is either blank to be the darkest corner of the shed or has another high clerestory window above the bed for cross ventilation (operable, in my reach, but high enough for privacy), plus whatever the bathroom needs.

I love my family but would like some me space. My husband has worked from home since the pandemic and his conference call volume often ruins my day or drives me out of the house. He's a collector from a family where everything has history and must be kept. I gave away most of what I owned at 35 and started over in a new country. (I'm on the spectrum and avoidant of noise, artificial/bright light, chemical smells. I don't like clutter unless it's MY stuff ;) I like to control my environment and that's pretty impossible with a partner and twins, who are like me but with different sensory profiles. I have accumulated a decade's worth of art supplies and things with sentimental value but they won't all be coming to the shed. Before marriage I lived pretty happily for a decade in a 55sqm/ 600sqft condo until my upstairs neighbors ruined it by installing hardwood floors against our rules and without my permission. I know this is a third of that size but my apartment was basically empty (although I admit to having a couple of stuffed closets and a space in a small storage room down the hall.) Unlike single living where organizing or downsizing makes room, in family life someone else just fills the space with their stuff. Basically I'd like to build myself somewhere else to go to prevent or recover from autistic burnout without actually leaving my family. I want the right to be inflexible about what goes there.

It could be a guest house or vacation rental later, fingers crossed my MIL doesn't move in. We're five km/3.5 miles inland from a pretty beach town on the train line south from Barcelona. I sometimes think about offering safe/notstealth parking to vanlifers, but my twins are still kind of young (12 in December) for contact with lots of strangers close to home. I'm not a total misanthrope but I do like people in small doses and living in a house with bars on all the windows to keep people out has been working on my subconscious. I'm not sure the site really justifies what I'm likely to spend building it, but my sanity cries out for it and all of it will likely pass to my sons eventually.  Their great grandparents' ashes are sprinkled here and I'm pretty sure the existing house is my husband's forever home after a half dozen different apartments with me around Barcelona in the last decade. I will be a snowbird or traveler when my kids are grown. He grew up summering in the Cubelles house and doesn't mind the heat. Sometimes we travel together. Sometimes we don't.

After this summer included a costly medical crisis in the US about my gallbladder where I was underinsured, I have let go of the idea that I might get to move home with my sons for some American years. We've never tackled US immigration for their dad because it is so expensive, seems so hopeless and he doesn't want it enough. I've coped with being a long-term expat by telling myself for years that it's temporary, but I think the next six years ahead and land owned by the family I married into is enough to coax me into putting down some roots...tiny ones.

I've always pictured a stick build but lumber is costly in Spain and there's only one building in the community built from timber. (My husband grew up referring to as 'the American house'.) Enric is likely to coax me toward a build more in keeping with the local style or push toward cheaper OSB ply, etc. (I'm paying, but he's handy and vocal.) I know Permies folks are wild about alternate building techniques but I married into a family of Normies. Strawbale or cobb might turn a yes to no. I'd like a natural-ish build without much paint or toxic components. I love the idea of sheepswool insulation and/or use of cork (instead of drywall? except in the bathroom, is that crazy?) I've seen some use of cork exteriors in Catalan builds, too but it's pretty expensive. I have some interlocking foam flooring pieces (picture what'ss used to put under fitness equiptment to stablize it) that I want to work in upcycled as extra ad hoc floor or ceiling insulation. I don't really know what I'm doing but I've watched a lot of videos by people who seem to... but who disagree with one another. This isn't going to need to pass code inspections, but I don't want it to be dangerous obviously. A little bit of 'we built it and it's weird' is ok as long as it's functional. No lofts, no ladders for me. I'm middle aged and feeling it lately. If it's hard-to-reach I don't need it. I already have an IKEA underbed storage bed that could hide some miscellaneous stuff. (Three versions twin, double and queen already purchased. Two out of three are stored in the garage since the house is smaller than our last apartment and has bunk beds.)

Nuts and bolts, does anyone have a spreadsheet they've already worked out about what you need for a small build that keeps your DIY from having too short a life? I think the piers get built with treated lumber and that there are various moisture wraps to protect layers. Part of me says, It's a rectangular box, how hard could it be? Enric has quite a nice woodshop in the garage," but I barely survived shop class in junior high. My grandfather and uncle both were missing tips of fingers from user error and I'm pretty anxious about power tools. I would like to be a badass and model learning the skills for my sons, but I'm also pretty afraid they will hurt themselves or each other or be the distraction that makes me hurt myself. We'll see whether Enric and I survive our chicken run collab. He definitely hasn't volunteered to build me this shed. We're housed, so this could be the slow build that takes years I see tiny house folks describe so often. I'd like my retreat the sooner the better, of course. If you read all of this, talk to me about anything you think I should consider or know. Resources, your experience, anything, please.

(I'm resting after what I hope is my last gallbladder-related procedure, so this became longer and more personal than I expected it to. Yes, I do want a bathroom even though it would be easier and cheaper without one. Could I plan the bathroom but fit it out later if it's a shed on piers? We four share in the main house at the moment. The guy on his phone on the toilet for an hour phenom is real. A long, uninterrupted bath is nearly impossible even if boys will sometimes pee on my compost pile instead. I'm pretty sure we'll hire a plumber. The bathroom in the existing house is badly done and I'm not sure how much of that was done by family members or whether they hired someone who didn't know what he was doing. It is tempting to think they'd get it right the second time but fool me twice might be the better line of thinking. I have considered composting toilets but my willingness to handle my own human waste significantly decreased after having to collect and monitor it for weeks in the hospital. TMI!)

Hello from Cubelles. Thanks in advance, Eileen

Eileen said, The site is on the third terrace level of the land with road access at the street level only (so not THOW).

For the benefit of other folks, may I ask what THOW stand for?

Third terrace level is not something that is common in the USA or at least Mr Google is not familiar with that.

Tiny House On Wheels

I will hazard a guess.

https://saunat.net/tuote/2-kerroksinen-mummonmokki/

Eileen.

I would also recommend to build with local style, which makes Catalonia one of the best looking places on Earth.
Please do not build from timber in fire prone areas with arid summers.
If you build using Porotherm bricks, you will have both insulated and natural, breathing walls. Otherwise I would recommend a normal reinforced concrete frame infilled with light clay.
20 m2 can easily fit a bathroom and a nice living/sleeping space.
It would also fit a kitchenette, however in hot summer places it makes no sense to use the kitchen anyway during half of the year and in winter time you could use a small masonry stove both for heating and cooking (and baking in the firebox).
If you could build 1.5 story tall, then you could sleep at the attic and have more space on the first floor.
If you could build 2 story house then it would be a normal small house with living/bath/kitchen on the first floor and two bedrooms on top.
Designing to fit existing dimensional constraints is fun and makes you creative and efficient.

Thanks for your interest. Yes, THOW means Tiny House On Wheels. I'm not anti, it's just that they're generally narrow to be road legal and better suited to rv site parking. Mine can't be mobile if built here, so it won't be on wheels and needn't be narrow. The THOW phenom has been hugely influencial on tiny house design, but I think 4m by 5m suits my site better and will give me more usable space than starting with the assumption that one dimension can't exceed approx 2.5m so should be that wide by 8m long to make 20.

Our land is a small slice of a mountain. At the ground level 'first terrace' there's a carport, garage, garden and pool. All of the other levels are accessible only on foot. Climb most of the way up the stairs and you'll pass the 'second terrace' which is a large ivy-covered area planted ages ago over a spot backfilled with construction rubble (we've been talking about it on another post, Anne), the 'third terrace' is at top of the stairs. The existing 3bdrm house is there, as is the shaded side lot where I want to put the tiny shed house to the east and an outdoor laundry setup to the west of the house. The 'fourth terrace' is a wooded lot up the mountain above the house. I had forgotten that this wouldn't be intuitive. I taught my kids to refer to it this way so that we could find each other more quickly. (My mom did the same thing at our Seattle house with a multi-level back yard calling them 1st, 2nd and 3rd Avenue. She wanted sibs to be able to help her find us quickly in an emergency.)

I'm attaching a picture of a shed style house that captures the vibe if not the design I'm describing. I've ruled out a lot of ideas I like that include decks, porches or screened porches because for my purposes those would count against the 20 square meters (approx 215 square feet) total allowed without permitting where I live. I'll likely go for less roof overhang and more interior footprint with the roof being 4m by 5m and the shed house interior footprint stepped in slightly from that to still have some eaves to the east and west.

Cristobal Cristo wrote:Eileen.

I would also recommend to build with local style, which makes Catalonia one of the best looking places on Earth.
Please do not build from timber in fire prone areas with arid summers.
If you build using Porotherm bricks, you will have both insulated and natural, breathing walls. Otherwise I would recommend a normal reinforced concrete frame infilled with light clay.
20 m2 can easily fit a bathroom and a nice living/sleeping space.
It would also fit a kitchenette, however in hot summer places it makes no sense to use the kitchen anyway during half of the year and in winter time you could use a small masonry stove both for heating and cooking (and baking in the firebox).
If you could build 1.5 story tall, then you could sleep at the attic and have more space on the first floor.
If you could build 2 story house then it would be a normal small house with living/bath/kitchen on the first floor and two bedrooms on top.
Designing to fit existing dimensional constraints is fun and makes you creative and efficient.

Cristobol Cristo,

Thanks for your reply.

I hear you about the local style because the overall uniformity does add something special to Catalunya, but I've gotta say that individually I've seen some of the ugliest houses in my life built here, too ;) I almost want to make a little gallery of some nearby stinkers and say, 'but at least it would be better than this!' Competitive breeze block and ironwork decor make for some funny versions of keeping up with the Joneses. Paving and covering entire lots with tile so you don't have to manage too many any living things is a pretty stark choice even if you throw in a potted lemon or two after the fact! I have opinions about gravel and other rock gardens (I don't even want to know what Jordi spent on river rock before he met me!) The Franco-era assumption that thugs may be coming through the windows at any minute also makes for some crazy unsafe homes with fireplaces. I've been lobbying my husband to prioritize fire egress from bedrooms. The modern fear is okupa (squatters) and they can be a real headache, but I'd rather risk a break in than not be able to get out in a fire.

I will try to learn more about Portotherm bricks. I was hoping a sensible roof could mitigate enough of my fire risk. Getting lighter materials to the site is also a factor in favor of a little timber but I've asked for advice and should probably now take it.

Going up a half or full story would exceed the 20 square meter footprint exception under the rules (according to my husband, who admittedly sometimes fibs to discourage me from doing things he doesn't want me to do). They'd count the extra area on the addition floors. I'd like to maximize while still making this look like an outbuilding of the main house. If I tried to go up extra stories it would definitely attract unwanted attention and might dwarf the already petite house.

A kitchenette where you don't cook much still makes sense to me in any season. Tea, juice, museli, yogurt, fruit, sandwiches, salads, snacks, a place to store food and hand wash dishes, etc. I didn't grow up on a giant Iberian hot lunch so that's what I usually eat anyway. I would call it a 'butler's pantry' or some such bougie thing, but then people picture wine, glasses, liquor and an espresso maker. I won't have an oven, microwave or hood fan, but I'd like a plug in hob to boil pasta or make an omelet if I feel like it that I can tuck away when I'm not using it. My husband is celiac. It would also give us a chance to reduce gluten contamination in the main house. I'm a good pie baker, but never make them anymore since rolling out dough looks like a biohazard to him. I could bring prepped food in to the other house to bake but not risk spreading flour around where he preps food. I could also keep my husband and sons from eating my cashe of preferred foods before I get a chance at them ;)

I do like to work with constraints, too. Some things that haven't been fixed would likely get fixed up once they're the 'view' to the tiny. That bit of fence keeps anyone from going off a cliff but there's room for improvement for sure. Photographing in each direction made me want to repaint the existing house, too. My mother-in-law said she picked that color because the pine pollen blends in on it! Live and learn.

Cheers,
Eileen

I just noticed that 20 m2 is counted with the envelope of the roof.
In this case: Porotherm 25 cm + 15 cm for nice cornice and protruding tiles gives 40 cm of wall thickness (plus 3 cm of plaster).
It leaves you 4.2x3.2 m of floor space. If you build shed roof, the bathroom could be located under the taller part. With 1:2 roof slope the height difference would be 1.6 m.
Using the celing of the bathroom structure and brick brackets in the wall (to support some wood beams that could be removed) you could have 4.2x1.65 m sleeping area and nobody would call it 1.5 story, being naturally enclosed into shed roof of a building looking like an outbuilding.
The space between bathroom (2x1.5, 2.15x1.65 including interior wall thickness) and the exterior wall would be 155x215 cm for a kitchenette. Reducing the bathroom width would increase kitchen space.
Living space would be 205x320 cm.
It would need more detailed analysis and dimensions of toilets/bidets, sinks, fridges, etc. to make sure the tiny space can be furnished efficiently.
Could you include a basement, without  any restrictions?

How vital is the short soaker tub to you? You said there is a pool already on the property.
I've been looking at tiny builds for a few years and also considering some of those ideas for our basement upgrade.
Being able to age in place is something I've been putting at a high priority so am trying to plan in accessibility.
For a small bath, making the whole room a "wet" room seems to give the best space, access and usefulness value. A folding, wall mounted seat and a flexible shower head, with no closed stall, would make it very accessible, even with the small size. Easy to clean too!

For the kitchenette, my uncle did a bunkie a few years ago and the one he did was to put in a short bit of countertop that was just wide and high enough to go over the top of a bar fridge. Total length is a bit over double the fridge space and the rest is closed shelving. Open shelves above and there is lots of room a kettle, some canisters and any room temp foods on the countertop.
The same bunkie uses sliding glass doors as both the doors and the full length windows. Shows the best views and you don't lose another wall to a door.

Last thing I can think of is if you can cheat on the porch issue by using a sun sail? It's not permanent, so it shouldn't count but could give you almost the same benefit.

Dian Green wrote:How vital is the short soaker tub to you? You said there is a pool already on the property.
I've been looking at tiny builds for a few years and also considering some of those ideas for our basement upgrade.
Being able to age in place is something I've been putting at a high priority so am trying to plan in accessibility.
For a small bath, making the whole room a "wet" room seems to give the best space, access and usefulness value. A folding, wall mounted seat and a flexible shower head, with no closed stall, would make it very accessible, even with the small size. Easy to clean too!

For the kitchenette, my uncle did a bunkie a few years ago and the one he did was to put in a short bit of countertop that was just wide and high enough to go over the top of a bar fridge. Total length is a bit over double the fridge space and the rest is closed shelving. Open shelves above and there is lots of room a kettle, some canisters and any room temp foods on the countertop.
The same bunkie uses sliding glass doors as both the doors and the full length windows. Shows the best views and you don't lose another wall to a door.

Last thing I can think of is if you can cheat on the porch issue by using a sun sail? It's not permanent, so it shouldn't count but could give you almost the same benefit.

Dian,

The bath is pretty high on my list. Hot baths are one of my main sensory joys. Ideally I'd read a couple of hours a day there. I used to recover from my office job that way before I married and had my kids. (The pool is an unheated, above-ground pool...in a mosquito war zone (bat boxes are on my list). When the pool fails (hopefully after the kids finish high school)  I don't want another one. I have psoriasis (an autoimmune condition that comes with skin issues as one of its outward symptoms) so chlorine is terrible for me. I would like to create a natural plant-filtered pond someday, but not here. I will keep accessibility in mind (psoriasis may come with severe arthritis sooner than later, too) so faucet fixtures, door handles and drawer pulls should be well-chosen, too. I love the idea of a shub (shower plus tub) generally or a 'slipper tub' (a high-sided tub with the back shaped for comfortable long baths) particularly. I don't know what's going to be available where I live yet. I have an Obramat catalogue (think 'Lowes' if you're American) and there are specialty sellers around, but I'm not sure what my budget is yet. If I hadn't married into a Normie family I might go the livestock trough 'who cares' route, but my landlords are going to expect/prefer/demand something more conventional.

(A basement won't work here. Replying to another commenter, not because you're working on yours.)

A sunsail is a good solution. We have a lot of 'outdoor living' areas already. I'd be as likely to sit on the porch of the main house, which has a table and bench seat I like as anything. (Except mosquitos! That one might get screened in.) I mentioned it mainly because decks and porches are big in tiny house design and they're kind of ruled out here if I try to go the too-small-to-require-a-permit route. After the tiny shed is an accepted fixture for a couple of years it might magically grow a pergola or a grape trellis to the north to shade that door ;)

Really happy to see the Bunkie site. Those are new to me. Thanks. I probably won't buy one but I might emulate them. My last apartment's bedroom had two sets of sliding doors as the wall to the balcony (unfortunately right next to train tracks!) Heat gain and loss were a problem seasonally, but I agree generally about sliders. The house my parents built where I grew up on Vashon Island had double French doors as the main entrance. They reduce privacy and they're a bother to keep clean, but that would feel like home away from home, too.

Cristobal's comment about integrated half-level lofts is totally valid, but it's probably not my preference. I've moved a lot around Barcelona. In Sant Cugat had a room with a loft for a couple of years and I only used it as (dusty) storage. It never became the office or crafting space I thought it would even though it had a nice desk and chair and lots of supplies. That probably says more about me than the design element (or maybe that it was too far removed from my kids to adequately supervise them at that age). Also heat rises, so as a Pacific Northwesterner who already thinks Catalunya is too hot for a lot of the year I'm likely to stay below. The twins had a big loft, too but without full ceiling height.  They loved it but it made 'bedtime' awful for me as the mama. As a kid, I had the top bunk for years and didn't like it. Climbing down to use the bathroom is a drag. My vision is poor when uncorrected. I'd like to stumble to my bathroom safely without glasses in the middle of the night. Although my kids might feel strongly about me sleeping in the tiny shed. Perhaps it'll be a daytime napping bed and reading spot more than an overnight bed.

On a side note, I often hear people in videos refer to ADUs (accessory dwelling units) as 'a marital aid'. I never know whether they're implying that it's a love shack or a way to keep partners from divorcing because they're spending too much time together. I love my guy, but quantity time post-pandemic rather than quality time before it hasn't been great for us. He eliminated a long train commute, but still seems to have given those hours back to his employer while working remotely. It's like I live in a call center. He writes code for banking clients and it's like I've returned to a fulltime job an Amazon co-office without getting paid. The upside is that he comes to me for a hug when he needs to annouce, "People are so stupid!" but I miss having a couple of quiet, solo hours while the kids are at school and he's working.

I'm looking forward to feeling 'home alone' in my own space!

I currently live in a tiny house that was the dream of someone else.

Our land came with a shell and we finished the inside.  It took us about 3 years to get it to where it is now.  It will never be finished in my lifetime.

Our other tiny house was built very much like this one:

https://permies.com/t/49991/tiny-house-build

To me it is the design inside that makes it liveable.

This forum was very helpful for planning the inside of our home:

https://countryplans.com/smf/

Eileen Kirkland wrote:In Sant Cugat had a room with a loft for a couple of years and I only used it as (dusty) storage.

I understand. In this case you could shrink the bathroom to 1.5x1.5 m and it would fit a bathtub and a toilet. Bathtub faucet could be used like a sink, or very small sink could be squeezed in the corner. The bathroom would be located under the low part of the roof. You would have 320x250 cm living space - enough for a bed, table, armoire and a cupboard. The kitchen could have multiple storage shelves going up to the tallest part of the shed roof.

Toilets have a fixed distance from the wall that works, only constraint unless adding grab rails.
Your post foundation allows you place fixtures anywhere in the  future, just crawl under to relocate drains.
A wood fired/RMH hot tub would not count towards your sq. footage, and if part of a 'separate' deck/porch with trellis would be almost like a second room.
My daughter's school mini claustrophobic box apartment in Seoul had a 'bathroom' that was really just a toilet located next to a small shower, with a tile floor and glass partition separating it from the bed and workspace/kitchenette.
Poach storage ideas from the mass of online tiny home builders. Nothing makes a small space smaller as fast as clutter.
Dunno what it's like where you are at, but here, the packrats will destroy and carry away the insulation of your floor. Plywood sheet it for durability and airtightness. "BubbleWrap", "plastic sheets", fully useless.
Have a look at my skid shack thread. An awning, posing as a wall, would allow you some indoor/outdoor space for many seasons. Lightweight rolldown screen, the mosquito plan.
Stack plumbing vents in a common wall, reduce roof penetrations. In wall venting also possible. That would allow you to put a sink in a small island for example.
Casement windows open out and when placed properly cross ventilate a small space well.
Do you have a friend with a small crane? Build your roof on the floor/deck. Nice, flat, level, and square. Slide it aside, frame your walls in place, brace them plumb and SQUARE, pick the roof up and drop it on.  Save a ton of ladder work if you cannot walk wall tops.
In your mind build/plan the house from the roof down. Start at the end and work back. Allows you to foresee problems, not react to them.
Build the hot tub deck first, practice a little power tool usage, layout measuring and placing/fastening.
Cut a few decorative 'milk crates', garden benches, cabinets to store building supplies and tools, whatever. See if this really is something you are comfortable with.
Properly/respectfully handled power tools are neither dangerous nor scary. But inexperience and carelessness are.
Don't let your mind tell you it can't be done.

Tommy Bolin: "Toilets have a fixed distance from the wall that works, only constraint unless adding grab rails.
Your post foundation allows you place fixtures anywhere in the  future, just crawl under to relocate drains."  Good to know.

A wood fired/RMH hot tub would not count towards your sq. footage, and if part of a 'separate' deck/porch with trellis would be almost like a second room.
I'm under Spanish law. It would count. Anything built to create usable space does. Husband read it again and it says (paraphrasing) 'build over usable area' so I'm wrong in my previous post about having to step in for the eaves (.3m/1ft arguably not usable) to avoid exceeding 20sqm, but I really shouldn't plan to put anything major under trellising like a RMH or hot tub (even though that sounds magical). I probably could shade my front door with plants later. They're not monsters.

My daughter's school mini claustrophobic box apartment in Seoul had a 'bathroom' that was really just a toilet located next to a small shower, with a tile floor and glass partition separating it from the bed and workspace/kitchenette.
Sounds interesting. Any pictures?

Poach storage ideas from the mass of online tiny home builders. Nothing makes a small space smaller as fast as clutter.
Yes. Bryce Langston made a very comprehensive video of top storage ideas for tiny houses for his Living Big in a Tiny House YouTube channel, which I recommend.

I think in my case the kitchen, eating bars/desk will become multistorage - plus storage bed, medicine cabinet and possibly a closet on the bed side of the bathroom wall. I'm earmarking half of the south wall for future shelving or storage potential, but I think this will mostly be 'she-shed' (don't love the term) as I will not need to move out of the existing house to have this be my retreat. A lot of potential clutter is left in the family home where the rest of the family seems content to live like packrats.

IKEA Kallax shelves have many many moves with me and I will factor in the possibility of some of the 4 tall, 4 wide ones that're cramping my style in the existing house coming over. They're not terribly elegant, but I'm used to using them for multifunctional storage. One might stand in as a room partition for the bedroom and be adjustable until anchored. I will leave a generous Kallax width from the end of the wall if a slider/egress goes in the southeast corner, make sure the clerestory is above the likely shelf height and will think about where outlets go based on possible positions, too.

I'm still looking for a stellar solution to laptop, tablet and phone docking that isn't bedside and doesn't take too much countertop/desk space but also isn't too close to water/kitchen sink.

Dunno what it's like where you are at, but here, the packrats will destroy and carry away the insulation of your floor. Plywood sheet it for durability and airtightness. "BubbleWrap", "plastic sheets", fully useless.
I'll consult Jordi (husband) and Enric (brother in law). I think the local style is mostly brick and gaps (being cynical) but I'll keep in mind that. I have a lot of those gym floor mats that wouldn't appeal to rodents so maybe those are incorporated into the floor.


Have a look at my skid shack thread. An awning, posing as a wall, would allow you some indoor/outdoor space for many seasons. Lightweight rolldown screen, the mosquito plan.
Stack plumbing vents in a common wall, reduce roof penetrations. In wall venting also possible. That would allow you to put a sink in a small island for example.
I'm interested to learn more about these ideas. Thanks.


Casement windows open out and when placed properly cross ventilate a small space well.
Yes.

Do you have a friend with a small crane? Build your roof on the floor/deck. Nice, flat, level, and square. Slide it aside, frame your walls in place, brace them plumb and SQUARE, pick the roof up and drop it on.  Save a ton of ladder work if you cannot walk wall tops.
No crane, but we do have scaffolding. I need more friends ;)


In your mind build/plan the house from the roof down. Start at the end and work back. Allows you to foresee problems, not react to them.
A good mental exercise.

Build the hot tub deck first, practice a little power tool usage, layout measuring and placing/fastening.
Cut a few decorative 'milk crates', garden benches, cabinets to store building supplies and tools, whatever. See if this really is something you are comfortable with.
Properly/respectfully handled power tools are neither dangerous nor scary. But inexperience and carelessness are.
Don't let your mind tell you it can't be done.

Can't have the hot tub or deck but could build myself some cold frames or raised garden beds to get more comfortable. My father was always can-do, but also often drunk or hungover while building, so the example I grew up with stresses me out, too. DIY is not my happy place. I like watching reference videos but then there's always someone in the comments ripping them a new one about mistakes or what they should have done instead. I try to learn from it but don't know who to rely on. There are a few shifts for me to make for comfort beyond safety - metric, cost of materials when making mistakes, etc. I also get vetoed by my husband and BIL when I enlist their help and end up mad when they take big detours from what I drew/planned/wanted, then they declare me ungrateful about the finished product. (Small things like a vertical plant wall, a quail cage and a backpack/shoe rack; I can't even imagine how far wrong a house could go.) BIL is Catalan-speaking and deaf from birth so when we miscommunicate sometimes we really, really miscommunicate. We're building a chicken run this month. I almost guarantee the door will not go where I want it. I'm ok with easier when it's still functional, but I don't think he understands yet that I'll be moving a ton of compost material in and out.

Anything done with or around special needs kids can have its share of anxiety. I once took my boys bowling and could barely focus on the lane when it was my turn. I want and appreciate pep talks but balance them with my life experiences. One kid is extremely cautious and prudent (arguably anxious/avoidant like me) the other is the kind you find trying to light a fire with a magnifying glass...indoors. Kid ADHD where at most one step of an instruction sticks at a time makes even our everyday life tasks hard. My sensory profile means that anything loud already has me at the edge of my tolerance.

Work hired out has been done badly, with no regard for delivery dates and contracts aren't easily enforced her even if you do have a solid agreement. My mother-in-law's telling of the building of the existing house in the 1980s includes several steps in which work was bungled and/people kept her money and never completed work and simply became unreachable. The solar package we bought (from the monopoly power company earlier this year) was delivered several months late, the mechanical room had to be redone, they didn't patch the first wall they put it on, and the we still don't have the rebate. For my part I feel like a foreign target for being cheated and am mostly good at getting bids from people who can never be reached again or scheduled if they do answer. :P

It may sound like I'm trying to talk myself out of the whole endeavor, but I'd rather try and lament than die with the money in the bank.

I think a framed structure with insulation board, tar paper (roofing felt), mesh wire then add a mixture of cement/sand (add color if you like) would be a nice. Add plenty of windows and enjoy.

EweTube and the like are 95% self promoting, attention begging, drivel.  Anything with pulsing, garish lettering, bizarre facial expressions on a host carrying a selfie stick, has nothing useful to add to your mindspace.  I've been building houses long enough to realize most of the 'Tube is just  chimps lecturing the undeducated. I've been drunk and hungover while building, (not very often) my opinions might be suspect.
Books are calm, noiseless, free of trolls, and allow you to absorb at your own pace. Does not work as well for those that need 3-D and hands on. Sketching your ideas out if you can a bonus.

I'm little in the dark about how much of this you wish to do yourself. If you are at the mercy of helpers with their own agenda, sorry to hear that. If you are stacking your 'un'happy DIY place with uncooperative 'assistance', this can become shortly very stressful.
You should get used to planning/thinking in metric. Avoids static from uncooperative help and the need to constantly convert.

Wood framing with a metal roof might be the best choice for DIY. Barriers to knowledge entry are low. Can stop at any stage to regroup, mistakes worked around. It is also the most flexible for design. In Canada, 'metric' plywood and lumber just mimic US sizes, there's no trouble crossing over. Find out how lumber, (not timber) is sized in Spain, layout from that.
Real exterior grade plywood, not OSB. Cost difference for a project your size is minimal. I've inhaled enough OSB dust while cutting to know I hate it. Probably toxic while airborne. OSB does not take (waterbased) paint well, it's splinters are miserable and infectious, and it is quickly destroyed by water, swelling and falling apart.

Pictures of Pokey's apartment, no. Two years of foreign exchange in Korea was a serious, anxiety filled part of her life until she settled in. Think of an RV bathroom, RVs in general.

A chicken coop is not usable space covering the lot/earth, but an entirely separate little deck built to support a human filled tub is?

RE: the floor. I imagine insulating between the joists. Cold floors suck and waste heat, although that sounds like lesser priority for your case. Some barrier underneath is necessary to keep vermin, if any out, 'seal' in the dead air space. Anyone recommending bubble wrap has never built anything of substance. Probably a EweTuber. Plywood under or between the joists checks all boxes.

A 'kitchen' island on wheels could be self contained storage/counter space for all things cooking, shove against the wall when open space is needed.  

If you are decided on piers, beams, joists, and sheeting for your floor, you'll need a decent idea of you interior layout, to avoid having to workaround, head out, or move joists. Flat blocks nailed between joists flush to top support partitions/interior walls.

In order of immobility in general are HVAC, plumbing, then electrical. Whichever apply to you.
That is the order in which trades are allowed in after the house is framed, and the order in which a framer prioritizes layout. Framers can fix or accommodate anything they do/need.  Building in your mind from the roof down solves all structural and layout issues and is how good carpenters go about their work.

If I was in your situation, I would first frame the floor, get it sheeted, then layup for a bit. Then frame and stand walls, layup for a bit, then close it in with a roof, being mindful of seasonal precipitation.  This breaks your helper monkey's task oriented mental overload. Go have tapas and wine for a few weeks or whatever. When the deck is framed you can start actually laying out your partitions and fixtures, storage, or whatever. You'll have an excellent visual of your space to be, better reference for doors, windows, etc. Layout snapped by you on the floor makes arbitrary decisions less likely. Involve the helper monkey's input at the design part, help avoid all that pesky, counterproductive, thinking for themselves at future date. Drawing the four exterior elevations and a floor plan starts to get all the wizards into the same plane. Be clear about what is flexible and what is inviolable. Don't start without understandings about time and money. You'll need patience sounds like.

FWIW I've heard that folks with skin issues like 30% hydrogen peroxide or salt for hot tubs in lieu of chlorine. Maybe too expensive for a pool, don't know.

Good luck.

I’m going to ask a really dumb question:  how many “sheds” are you allowed to build?

Because if you can build two, one could be the “wet” one, with toilet, bath, wet part of kitchenette, and, I dunno, central command center for whatever irrigation you do.  (Plus sauna/outdoor-kitchen, etc.)

Then your crafting/sleeping space could gain a lot of room.  

Put a sun shade between them when weather requires it and you’re golden.

I love how much thought you have put into this, and hope you can build something that makes you happy.

Good thoughts from Tommy Bolin and Morfydd St. Clair

My jumbled reply:

Morfydd, I think multiple outbuildings are allowed on the property if they don't exceed the max sqm and don't call too much attention to themselves. (If a tinyhouse village cropped up there would be issues, but spaced around and relating to the main house they seem to be allowed. Many in my neighborhood have wooden kit outbuildings for tools or by the pool, etc.) The chicken run is being adapted from a pergola near the carport on the first terrace (street level); It's a different project from the tiny shed house (on the third terrace a.k.a. house level). I perhaps should have said monopitch instead of shed, but ideally it would kind of read as a shed/greenhouse to bypassers in addition to having a monopitch roof.

Books are fabulous. I think I go to the internet a lot because libraries don't have a lot of resources in English. Books with well-labeled diagrams to show Jordi and Enric would certainly be helpful and might be even better in Catalan, but then I feel a bit left out ;) I'm made a crazy by how much vocabulary it takes to correctly describe various pieces of wood based on their position and function. I know these terms all exists for a reason, but it's easy to get bogged down in it all when translating between English and Catalan (or even just trying to communicate about it in English).

I found exterior grade lumber, but not exterior grade plywood at the local big box store. That doesn't mean it doesn't exist, but it might be harder to come by. Comments on OSB noted.

I'll work on the mental shift to top-down design. When I know which bathtub, toilet and sink then I'll know how big to make the bathroom. (Reminder to self: I'd like a tall toilet and sinks and counters set taller than the usual. I'm 5ft7 but my sons will be very tall.) The rest is open plan, so otherwise the floorplan just looks like a rectangle with some doors and windows as described. Left to my own devices I'd make a spreadsheet with sizes and prices and keep on adding materials to it until I have something like a materials budget. Semana Santa (Spring Break before Easter) might be a good target date for framing the shed with help. I'm writing this up as the worst of the windy and wet weather begins here. Local low temps are in January.

Tommy's order for getting started makes sense to me. I will avoid calling anyone a helpermonkey though as they certainly wouldn't appreciate it. Enric built the garage and is the owner of all of the tools I'm hoping to borrow, so I should put a proper plan together and loop him in. He tends to 'overbuild' compared to what I'm used to (aforementioned drunk father making things relatively quickly out of whatever was on hand being my primary example), which can be a good thing or can be a budget-buster depending on how it plays out. If my inlaws/landlords want it permitted and approved despite size being within the size exemption, then I'll probably need an architect to draw the plan, but I'm hoping we can just go for it.

Thanks for indulging me as I try to think this through.

Eileen,

I have researched the Porotherm bricks in Spain and they are called Termoceramico:
Termoceramico bricks

This company is located in Almeria, but dimensions and pricing should be similar in Catalonia.
I wish I could get them here. For $1.45 a piece it's a steal. No fire, no bugs and rodents, quiet, warm, breathable and natural and every mason in Spain will erect walls for such a small building rather quickly.
I consider it the best building material for the mass produced houses. The second would be Ytong.
For 33x20x30 dimension you would need around 52/per course so with 15 courses (12 room height plus average 3 for shed roof) it would be only 780 bricks (8 pallets of 105).

Keep your feet on the ground, as you reach for your dream cabin. As you go along I am betting your confidence will grow.

With an assist from masters of the craft, you can relax and enjoy your journey, and keep your peace of mind.  Oh, and I wholly concur with the critique of OSB. Along with pressure treated wood, it is not created in a workshop, but in the seventh circle of he'll. Avoid.