Planning to build a tiny house inside a commercial greenhouse in 4b climate. Totally insane or not?

Hello everyone reading this!
Not sure where to start because it's my first time reaching out to people with similar ideas and values but here we go!
I'm very lucky that we have land in my family but it is not permitted to live there or build anything permanent but a greenhouse would easily be approved and after seeing a lot of NaturHus and tiny houses builds, I'm thinking more and more it's doable.
I asked for an estimate for a Harnois greenhouse, 24' by 50' and 16' high, all polycarbonate. The reason for choosing that height is because the horizontal supports need to be high enough for me to build living quarters and that support in this model is 9'. If anyone has an idea of what it might cost, i'd be grateful (very impatient to get the quote!).
I also asked for a quote on solar power since there's no power there and i need to decide on a rainwater collection and distribution system. I will have to supplement with a generator, just for safety. I'm looking at building a RMH inside and also heating the insulated earth floor with radiant heating with the Jean Pain method (wondering if i could put the heap inside or would that produce too much humidity or gases). Or doing radiant with the RMH. I would dig down about 2', put some gravel for drainage, then insulation, then put some of the soil back and compact it mechanically, put down a layer of tarp (the stuff that prevents weeds to grow), then the tubing for the radiant heating and then a cob layer.
The space inside will contain living quarters, thinking of building on skids with a maximum witdh of 8.5' so if i need to go i can have the unit put on a platform and moved. The rest of the space will be a huge woman cave for all my crafting, building, some growing of veggies and transforming, experimenting with sprouts, making objects out of found materials, etc. I'm thinking of keeping my water supply inside too instead of digging down below the frost line which is 5' here.
Other infos about the site/location: Eastern Québec, great sun exposure on site year/round, site on very slight slope (dig will be level) ideal for drainage, more rain than i'll ever need and 10-12 feet of snow/year, potential sun energy from 58 to 124 Kwh/m2 (the best month being march). The coldest days are -25C (colder with wind) but that's not the norm in winter.

So here are some questions i have for you:

We only have an old tractor there, would that be enough to maneuver things around? What kind of equipment should i look into?

What would i do with the grey water? Planning on a composting toilet.

What temperature inside the greenhouse can i potentially achieve with an RMH and radiant heat? The living quarters will be insulated.

Can i place my wood composting pile inside?

With the water tanks inside, won't the water get insanely hot in summer? How do i prevent it (and the pipes) from freezing in winter?

How much do you think the whole thing will cost?

Can i get a big dog? Please please i want a big dog! Lol

English is my second language and i'm not really good with all the technical terms yet but i'm learning a ton from reading on here!
Thank you so much!

Hi Marie,

Welcome to Permies.

Wow, that's a big ask. I love your boldness and vision. You stated that you're not permitted to live there or build anything permanent. So... are you planning on living there? That could cause problems with the authorities prohibiting you from living there. I'd look for the language that specifically addresses how long you can stay uninterrupted before having to vacate for a certain amount of time. I've seen laws and ordinances like this before, and some of them are quite vague. Others are very specific. Can you stay there for a week and only have to leave for a day or two?

I don't know any of the dirty-hands stuff you're asking, but I think with all of the time and $$ you want to put into this, you'll want to be sure how much uninterrupted time you can spend there.

Thank you for the welcome John!

Jim, i plan to live there full time! It's quite secluded, the only people who'll see the structure and maybe deduct that someone lives there is a farmer neibhour that is very chill and he's also counting on us to not tell he built himself an illegal shack further in the forest. The main road is maybe 500 feet from our land but is completely encased in forest. It would be just for vacations but i need a place to stay and can't really afford anything other than the crappy city appartment i have now. If it comes to the town's people ears that someone is living there i could probably come up with a few reasonable explanations and if they still go ahead with trying to evict me it will (could) take years. In rural areas here people don't really care what other people do with their lands as long as they don't bother them. I know it's a risk but after thinking about ir for years, i feel quite strongly about my decision! I'm very resourceful and creative, i think i can come up with something that will work and i don't need much.

 Welcome Marie!
You have a lot of cool ideas.
I think this kind of arrangement could be amazing.
I've often thought I could only live in a tiny house if I also had a giant barn.
This would be like a tiny house IN a giant, well lit barn.

I definitely think you should keep your water  storage inside of the structure, to add to the thermal mass.
Paint the water tanks black, cover with reflective insulation during the summer.
Uncover the tops at night for radiant cooling.
I would run the grey water through a biochar filter into an aerated pond and raise duckweed in it.

You could put the water tanks and tiny house on top of your radiant floor.
The water storage could also gain heat by immersing a coil of pipe in it, and connecting that coil to the radiant floor system.

I think a compost heating pile would be fine in such a large greenhouse
Topping the pile with finished compost/biochar and planting it as a hot bed could provide filtration and food production.

Bonjour Marie Gen! Welcome to Permies. You express your thoughts with great clarity -- I wish my French was half as good as your English.

I love the concept. Personally I would ensure the living area has fresh air from outside, not from the greenhouse (mold, pollen etc.).

Do not assume that being invisible from the road means nobody can see you. On the contrary, everyone can see you if they want to. We had a similar discussion you might find interesting: https://permies.com/t/146038/Stealth-Cob-House-Greenhouse-secret .

It only takes one "busybody" to set the wheels of local bureaucracy in motion. The easiest weapon against you may have something to do with proper disposal of sewage. Be prepared.

Douglas Alpenstock wrote:Bonjour Marie Gen! Welcome to Permies. You express your thoughts with great clarity -- I wish my French was half as good as your English.

I love the concept. Personally I would ensure the living area has fresh air from outside, not from the greenhouse (mold, pollen etc.).

Do not assume that being invisible from the road means nobody can see you. On the contrary, everyone can see you if they want to. We had a similar discussion you might find interesting: https://permies.com/t/146038/Stealth-Cob-House-Greenhouse-secret .

It only takes one "busybody" to set the wheels of local bureaucracy in motion. The easiest weapon against you may have something to do with proper disposal of sewage. Be prepared.

Thank you Douglas for your input!
The fresh air idea is noted, it’s a great suggestion.
I will be able to have a permit for the greenhouse and solar panels and plan to make the tiny house movable which is considered an rv here and is allowed. I will have an address in the city near by and an alternative place to stay. As someone commented on that thread you suggested, inspectors here are scarce and I won’t be that worried about that but it’s something to keep in mind for sure!

William Bronson wrote:  Welcome Marie!
You have a lot of cool ideas.
I think this kind of arrangement could be amazing.
I've often thought I could only live in a tiny house if I also had a giant barn.
This would be like a tiny house IN a giant, well lit barn.

I definitely think you should keep your water  storage inside of the structure, to add to the thermal mass.
Paint the water tanks black, cover with reflective insulation during the summer.
Uncover the tops at night for radiant cooling.
I would run the grey water through a biochar filter into an aerated pond and raise duckweed in it.

You could put the water tanks and tiny house on top of your radiant floor.
The water storage could also gain heat by immersing a coil of pipe in it, and connecting that coil to the radiant floor system.

I think a compost heating pile would be fine in such a large greenhouse
Topping the pile with finished compost/biochar and planting it as a hot bed could provide filtration and food production.

Thanks William!
Yeah that’s what I’ve been dreaming about for years! I love old barns too and if buying land with a barn on it was an option I would probably have gone that route.
I love the idea of a reflective insulation for the water tank, I had not thought of that.
I think I would keep the compost pile just wood product though because I want to control the temperature and the amount of time it takes to compost to have consistent heat through the pipes for the radiant floor. The Jean Pain method is great in that regard even though you have to dismantle it in the spring and do it over again in the fall. There’s lot of trees on our land that fall every year that I can mulch and use. I’m thinking I could probably exchange the finished compost for some goods or services, lots of small growers in my area needing it.

What an inovative idea Marie!  I'm quite intrigued by the idea of a tinyhouse inside a big tall greenhouse!  Keep us updated please on your progress.

Hi Marie.

By far the biggest source of heat loss in winter is the polycarbonate so having all the walls and ceiling poly will bleed out heat really fast. Using poly only on the south side reduces your heat loss dramatically in the winter.

Also, most people think that keeping a greenhouse warm is the biggest problem and that's certainly a challenge where you are. But cooling in summer is a much larger problem since the greenhouse can turn into an oven in less than an hour without a LOT of ventilation. So replacing the poly on the west and north walls with insulated walls will reduce the incoming heat that you won't need or want in summer, and reduce heat loss in winter.

I suggest looking into the basics of greenhouse design and operation before spending a lot of money on a structure. There are a lot of factors to consider, especially if you plan to live inside the greenhouse for any amount of time.

Regarding privacy or anyone knowing what is on the property, there is no such thing as privacy with the satellites taking detailed pictures of the earth. If someone want to know what's on your land, they only need to look up the latest pictures available from many sources online. That doesn't have to stop you from doing what you want to, but it's something to consider.

Good luck and welcome to Permies.

I don't see why your idea wouldn't work(Ignoring legal issues)
A commercial greenhouse even without out added heat will act like a tent trap heat leaking out of the living area and will also keep wind off the living area.  On sunny days it should be much warmer inside the greenhouse than outside, on cloudy days it should be slightly warmer inside than outside.

Greenhouses like that don't hold heat very well when the sun stops shining and require a lot of energy to keep warm.  A local florist has 4 of them roughly the size you are thinking a few years ago she said it cost 10,000 a month to keep them heated in January and February(in northern Wisconsin) so I have my doubts that you would be able to keep it even above freezing all winter without a constant fire and going through tons of wood.

Instead of a commercial greenhouse you may want to look at passive solar greenhouses designed for Canada.  They can be designed to stay above freezing without added heat even in the coldest Canadian night.

Instead of building a living area inside why not park a camper inside.  I have family who live in a similar set up.  The camper is basically used as a bedroom and  a inner shelter in cold weather.  Otherwise a section of the shed it is in is the living room and kitchen.

Your gray water can be use to water plants or simply dumped.  I assume you will be hauling water in so you will probably try to use as little as possible, so you probably won't be producing much gray water.  

I think a composting toilet is a good option, however I prefer a homemade one with a bucket that you empty in a compost pile every day instead of a commercially made one.  The homemade one is cheaper, doesn't use electricity, doesn't back up if it gets to cold, and is way less disgusting and less mess when it finally comes time to empty it.

Any venting for cooking, heating, propane fridge or plumbing in the living unit will have to be also vented through the greenhouse.

Unheated greenhouses that hover right around freezing during the warmest part of the day have a strange way of sublimating water out of the soil and growing hoar frost on every shaded surface.  A little bit of added heat or leaving a door open to keep it colder prevents this.

The two main questions that come to mind regarding function are:
1. How will you keep cool in the summer?  
2. Green houses can often by humid.  How do you mitigate this in the house to prevent mold issues?

Otherwise, sounds like a great idea.

Congratulations on your bold plan! I think it sounds very charming to have a cottagette completely inside a greenhouse, like an inside-out conservatory! Be sure to choose a dog that doesn't bark much, and then find a job to suit that dog. Dogs with jobs are happier, and people who dislike dogs sometimes dislike dogs with jobs less than pets. Newfoundlands are said not to bark much, and would suit your climate. They make excellent search and rescue dogs.

What will your ostensible reason for having a greenhouse there be? Will you have a business license, or whatever it may be that Canada chooses to require of businesses? In the US it is sometimes protective to have a business license of some kind.

We have two sets of friends who live in non-permitted structures, both of them have children, but enforcement is somewhat lax here on structures, and they would be permitted to live on their land, had they chosen a different building technique. Only one of the two families has any anxiety about it, and that comes from their water supply, which they obtain from a neighbor. Apparently, even acquiring water for free from a neighbor's private well would be enough to draw serious unwanted attention, and trading for it would be worse, and paying for it would be very serious. Both families have outhouses but only one uses theirs. Both families are very active in their towns and beloved members of several small sections of the community for the volunteering and mentoring that they do.

[quote=Robin Katz]Hi Marie.

By far the biggest source of heat loss in winter is the polycarbonate so having all the walls and ceiling poly will bleed out heat really fast. Using poly only on the south side reduces your heat loss dramatically in the winter.

Also, most people think that keeping a greenhouse warm is the biggest problem and that's certainly a challenge where you are. But cooling in summer is a much larger problem since the greenhouse can turn into an oven in less than an hour without a LOT of ventilation. So replacing the poly on the west and north walls with insulated walls will reduce the incoming heat that you won't need or want in summer, and reduce heat loss in winter.

I suggest looking into the basics of greenhouse design and operation before spending a lot of money on a structure. There are a lot of factors to consider, especially if you plan to live inside the greenhouse for any amount of time.

Regarding privacy or anyone knowing what is on the property, there is no such thing as privacy with the satellites taking detailed pictures of the earth. If someone want to know what's on your land, they only need to look up the latest pictures available from many sources online. That doesn't have to stop you from doing what you want to, but it's something to consider.

Good luck and welcome to Permies.[/quote]

Hi Robin, thank you for your thoughtful answer!

I have looked extensively at greenhouses buildings and systems and i know a lot about passive solar buildings as well. I wish i could visit such builds (which would help a lot with my questions and why i'm here) but they are very uncommon here for many reasons such as electricity is nationalized and very cheap and building codes are very restrictive.
My area gets maybe 10 days a year of temperatures over 30C 86F and since i'm not that far from the St-Lawrence river i get quite nice winds. I plan to have a roll down panel with bugscreen the whole lenght of the greenhouse, an 8'X8' door on the west side (predominant summer wind) and another opening on the east side to get as much ventilation as possible. Do you think that would be enough for ventilation?
I did think about replacing the poly on the north side with insulated panels and i'm still looking into it. I'm waiting to see what the basic kit from the manufacturer costs and then i'll adjust my plans. My budget is admittedly tiny so i'm not sure how much i can do yet. I want to be able to keep the greenhouse around the insulated living quarters just above freezing which is why i plan to excavate and create a sort of insulated earth slab with radiant heat going through. Maybe some passive air ducts to redirect some of the heat from the peak back down to the floor too?

J Hillman wrote:I don't see why your idea wouldn't work(Ignoring legal issues)
A commercial greenhouse even without out added heat will act like a tent trap heat leaking out of the living area and will also keep wind off the living area.  On sunny days it should be much warmer inside the greenhouse than outside, on cloudy days it should be slightly warmer inside than outside.

Greenhouses like that don't hold heat very well when the sun stops shining and require a lot of energy to keep warm.  A local florist has 4 of them roughly the size you are thinking a few years ago she said it cost 10,000 a month to keep them heated in January and February(in northern Wisconsin) so I have my doubts that you would be able to keep it even above freezing all winter without a constant fire and going through tons of wood.

Instead of a commercial greenhouse you may want to look at passive solar greenhouses designed for Canada.  They can be designed to stay above freezing without added heat even in the coldest Canadian night.

Instead of building a living area inside why not park a camper inside.  I have family who live in a similar set up.  The camper is basically used as a bedroom and  a inner shelter in cold weather.  Otherwise a section of the shed it is in is the living room and kitchen.

Your gray water can be use to water plants or simply dumped.  I assume you will be hauling water in so you will probably try to use as little as possible, so you probably won't be producing much gray water.  

I think a composting toilet is a good option, however I prefer a homemade one with a bucket that you empty in a compost pile every day instead of a commercially made one.  The homemade one is cheaper, doesn't use electricity, doesn't back up if it gets to cold, and is way less disgusting and less mess when it finally comes time to empty it.

Any venting for cooking, heating, propane fridge or plumbing in the living unit will have to be also vented through the greenhouse.

Unheated greenhouses that hover right around freezing during the warmest part of the day have a strange way of sublimating water out of the soil and growing hoar frost on every shaded surface.  A little bit of added heat or leaving a door open to keep it colder prevents this.

Hi J, thank you so much for taking the time to reply!

I have looked extensively at greenhouses buildings and systems and i know a lot about passive solar buildings as well. I wish i could visit such builds (which would help a lot with my questions and why i'm here) but they are very uncommon here for many reasons such as electricity is nationalized and very cheap and building codes are very restrictive.

I had a camper but it was rotted so i completely gutted it and kept the frame on wheels and might use that to build tiny on top. I really don't like campers for more than a few days, i'd rather have something small but well built and comfortable. I would love an al fresco kitchen in the greenhouse!

I will be collecting and storing rain water and if i plan this part correctly, i really don't think it will be an issue. I haven't figured it all out yet but i'm getting there.

I did think about replacing the poly on the north side with insulated panels and i'm still looking into it. I'm waiting to see what the basic kit from the manufacturer costs and then i'll adjust my plans. My budget is admittedly tiny so i'm not sure how much i can do yet. I want to be able to keep the greenhouse around the insulated living quarters just above freezing which is why i plan to excavate and create a sort of insulated earth slab with radiant heat going through and heating with a RMH during the day. Since i plan on being there full time and fire wood being readily available it feels like a no brainer. I had this idea that the moisture problems i read about in greenhouses is because it's being used for plants (duh) and thus there's watering happening and a lot of fresh soil. Since growing will be a minor thing in mine i didn't think moisture would be an issue, am i wrong?

I appreciate your input!

Riona Abhainn wrote:What an inovative idea Marie!  I'm quite intrigued by the idea of a tinyhouse inside a big tall greenhouse!  Keep us updated please on your progress.

Thank you Riona! I have all my fingers crossed that i can figure out how to make a version of this a reality! I will keep you guys updated for sure.

I think your idea is a good one. I have one concern though, due to the required stealth. Do you intend to use any lighting in the greenhouse after dark? I ask because that greenhouse will light up like a beacon.

Here's a light aimed at my 'nursery 15 feet away.


Here is the same light placed in the greenhouse from 10 feet distance.


Here is a view from 50 feet away.


Oh, look, someone lives there!

Marie Gen wrote: I had this idea that the moisture problems i read about in greenhouses is because it's being used for plants (duh) and thus there's watering happening and a lot of fresh soil. Since growing will be a minor thing in mine i didn't think moisture would be an issue, am i wrong?

I appreciate your input!

I have two dormant greenhouses at the moment.  On is insulated on 3 sides and double pane glass to the south, it gets well above freezing any time the sun shines.  The only time it has moisture issues is everyday when the inside just warms up to about freezing over the course of a few minutes the windows will fully fog up , then as it warms up over the next 10 to 20 minutes the windows will clear from the top down causing the inside to be quite humid.  Once the window are clear the humidity goes down as well.

The other is a unheated building completely wrapped in plastic with 10x30 foot greenhouse one the front simpley made of 8 mil clear plastic.  That one rarely gets above freezing and everything inside the building is covered in a thick layer of frost that I am pretty sure was sublimated out of the ground.



Another person suggest light would be a problem.  It isn't at all out of place for greenhouses to be lit up like small cities all night long to give the plants artificial light.  So depending on how you do it, light from living in there may not stand out at all.  And with modern LED lights it would be possible to fully light the greenhouse all night with a modest solar electric set up.  (I am assuming you don't have power on site)

If I were in your shoes I would consider:

Building the North, east and west walls out of earth bags or straw bales
Possibly banking dirt against those walls to earth shelter it.
Build a framed shed roof and insulate it heavy. Insulation could be fiberglass, foam or straw.
Frame the front wall with 2x4's every 2 feet.  Make the front wall match whatever your ideal angel is for the most heat in the winter.  Then cover the inside and outside of the front wall with poly film held in place with lath.

Such a greenhouse would probably not cost any more than a kit.  And it would be well insulated to hang on to any heat you get from the sun or add through burning wood.  

You could even partially build it underground to retain even more heat from the earth.

If built with the proper over hang it will gain and hold heat in the winter and shade everything inside in the summer keeping it cool.

Our insulated greenhouse is the nicest place on our farm on sunny spring days.  We finally get long sunny days that just start to get above freezing and inside the greenhouse it can be 85F.  Which after a long winter is a wonderful place to work and soak up the heat.  Then in the summer it is shaded and has lots of venting so it doesn't get much above ambient temperature in there.  What would make it better is more insulation and a longer overhang on the roof.

[quote=Marie Gen] My area gets maybe 10 days a year of temperatures over 30C 86F and since i'm not that far from the St-Lawrence river i get quite nice winds. I plan to have a roll down panel with bugscreen the whole lenght of the greenhouse, an 8'X8' door on the west side (predominant summer wind) and another opening on the east side to get as much ventilation as possible. Do you think that would be enough for ventilation?[/quote]

It seems like there is a lot of variation on what's suggested for passive heat management in greenhouses. One source says that the ridge ventilation area should be equal to the lower (incoming air) ventilation area, which makes sense to me. Also, each area should equal 20% of the footprint of the greenhouse. This seems like a decent rule of thumb, but it still comes down to the amount of polycarbonate exposed to sun vs. air exchanges per minute to remove the heat. And of course having steady winds to drive the air movement is a big bonus in summer.

The course I took on greenhouse design made it very clear that ventilation is the one parameter that is usually under-sized. What shocked me was that during summer, ventilation should be in the range of 1-2 air exchanges per minute (not hour!). That's a lot of air that needs to move all the time. Although the outside temperature definitely has an impact on cooling/heating, it's the sun shining on the poly that drives the heat up so fast.

One thing you might consider is using metallic shade cloth in the summer. You can get it in various levels of light blocking, and this will help a lot with heat management. In the summer your plants will still get plenty of light due to the long days.

Hello all that took the time to reply to my post! And all of you just reading it now of course.

It was amazing to have other brains working on it since mine is going 24/7 and not making much progress. You have sent me down some very very interesting rabbit holes and i'm humbled by all the creativity and knowledge i encounter.

I have a few more ideas to run by you and some questions also.

A lot was said about privacy because i'm not suppose to live there but it really isn't that much of a big deal, even when it's all lit up. I checked on site last sunday and it's definitely not visible from the road and that road is really not busy. I asked my Dad about it and he says it's really not a concern and if he's not concerned then there's really nothing to worry about.

I learned from my Dad that the soil is mostly rocks and sand topped with 12-24 inches of good soil. As i plan to use the excavated soil as a insulated slab, is it possible that it will be too much trouble because of the rocks and sand? Sand is not a good mass and won't rocks shift and possibly cause my top layer of cob(?) to crack? I've been looking at alternatives for cob because if i can't find clay locally that won't be an option but that still seems like the best option at the moment to make a mass floor that will be heated by the sun and probably a water radiant system too.

All of you who said insulating the north (at least) side were correct. I didn't want it to be true but it is. As i'm still focused on using a standard 24' by 48' by 16' greenhouse kit, i'm looking for ways to insulate the north wall in a non-permanent way. I thought about fabricating panels that would have insulation facing the outside and a reflective surface on the inside. I'm thinking of a lightweight frame made from aluminium or just light timber like cedar. The panels would be 6' wide and about 13' long and would be suspended between the arches on an angle leaning the reflective surface towards the floor during winter and then swung up inbetween the arches so the the reflective surface faces up during summer to help with overheating. Again, my desire is to have a space that doesn't freeze over winter but not to heat it like a house. These panels and the insulated heated earth slab might not be enough still but i feel like that would get me much closer. I'm waiting on an answer from the greenhouse manufacturer about it being solid enough to pile up snow quite high on the north side. I don't think he'll like that idea but i'm hoping it's structually doable.

I'm now trying to estimate my water consumption to be bale to size the tanks i would need to store rainwater as it will be my only source. I'm very grateful for all the info i found here about using grey water twice, like shower to washer. The bit that is concerning is that it seems a pump is required for everything! I would like to use gravity as much as possible but i don't know how practical it would be. I thought i could build the bath/shower combo high up on a platform, over storage or something, and then let it drain directly into the washing machine but for the rest of the water system i'm not sure i can calculate the impact putting the water as high as possible would have on the size of pump i would need to feed the sink and shower.

All right, i'll stop for now because that's already a lot! Going back to reading the wonderful book i purchased: The rocket mass heater builder's guide!

Thanks, stay safe.

Maybe try this:

Thank you for the suggestion William! I’m sorry I didn’t see your reply before.

I was thinking more of 3.5’’ foam boards with a reflective film on the back to get get a good insulation value and so I get something rigid I can lean things against.