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Birdman
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# Posted: 3 Feb 2021 20:46 - Edited by: Birdman
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Hi all,
I'm in the process of planning my off-grid cabin build. Couldn't be more excited! I purchased a 1 acre piece of land in the foothills of the Cascade Mountains, about 1.5 hours outside of Seattle.
I've never built anything before, so this will be quite the adventure for me. Luckily I have a lot of very talented friends who will help out when the time comes, but I want to be primarily driving this project.
I am looking for input on design. I am limited to 200 sqft measured at the foundation. I think I have settled on a 12x16 lofted lean-to / skillion design, both for simplicity and efficient use of building materials. The frost line here is between 12-18" deep, and since this area gets a lot of moisture and I want this building to last I am planning on Sonotube concrete pier foundation. One question I had was how do I figure out the diameter, number, and spacing of the foundation tubes?
Is anyone familiar with icreatables plans? This is the design I am considering:
https://www.icreatables.com/sheds/12x16-LTL-lean-to-loft-plans
As far as electricity goes, I am planning on using electric bike batteries that will be recharged using a combination of a propane generator and just plugging in the batteries at the local bar.
For heat I am going to be using one of the Chinese diesel heaters that have become very popular among the van conversion crowd. Based on feedback I got from a friend who built a 400 sqft cabin in cold Quebec, we both feel this 5kw heater should be up to the job.
Any input you all have based on this info? Or things I should know about building in a snowy area in the PNW?
Much appreciated!
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Fanman
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# Posted: 3 Feb 2021 21:13
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If you have a propane generator why not propane heat as well? Then you don't have to deal with two kinds of fuel.
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Birdman
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# Posted: 3 Feb 2021 21:29
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Fair question! I had actually purchased the diesel heater for another project that I didn't end up using.
I also wanted diesel because it is lower energy consumption than RV style propane furnaces, cheaper than RV furnaces, and it produces dry heat vs wet heat that even vented propane heaters produce. It's super wet here in the PNW, and we're snowboarders who really need the ability to dry our gear after a day of riding.
I'm open to suggestions for heating, but since I already have the diesel heater and the batteries needed to power it I'm pretty well set on that front.
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gcrank1
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# Posted: 3 Feb 2021 21:33 - Edited by: gcrank1
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I may be the odd one out on 'foundation work' for a shed size cabin, I like em to 'float'. Im good with cement surface pads (Ive used 'silo block'), stacked blocks atop to level out and skids/beams to build the box frame & joists on. Use a piece of asphalt shingle between cement and wood and pressure treated if within 12" of the ground.
What voltage do the e-bike bats have and what do you figure to run with them?
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Birdman
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# Posted: 3 Feb 2021 23:18
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Yea I'm still not entirely sure on what foundation to go with. The sono tubes definitely look like they will take some work to get the holes dug, but then I shouldn't have to worry about settling and leveling the structure right?
Do you think a fully finished 200 sqft cabin would be too much weight for the foundation you're describing? I can't seem to find anything on the silo blocks, got a link or a picture I can check out?
The ebike batteries are 48v 13.5ah each and I have two of them for around ~1300wh. I've got a 30-60v to 12v 20A adapter (https://www.amazon.com/gp/aw/d/B07WWN2N6D?psc=1&ref=ppx_pop_mob_b_asin_title) to bring that 48v down to a usable voltage. Pretty stoked on these if they end up working out! Really nice to have such a portable battery, and two of them so I can manage charging them while I'm on the go.
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gcrank1
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# Posted: 4 Feb 2021 00:10 - Edited by: gcrank1
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In south central WI I built a 12x24' with a 12x12 loft and a Swiss chalet style roof in '83-'84. It was bigger than I had originally intended and thus heavier. In 37ish years I only had to jack up the center front by about 1/2" when my centered door started dragging the threshold.
Depending upon your soil type you may have to do some ground prep. Mine was on a sand/gravel hilltop, I just put the blocks down in the right places, built the box frame, squared and leveled it up and filled it with joists.
I eventually ended up setting my cabin up for genny input at 120vac, plug & play. Then it was an easy thing to invert my solar charged 12v bat-bank to 120vac to swap the infeed. I have a long run from the powerhouse so the line losses were important to minimize, much easier/cheaper on wire if the bat can be inside the cabin. I run the gen for heavy loads only.
Are those batteries LFP's? If so you are supposed to ne able to use the ah's 80-90% depth of discharge (dod) and stay in battery happiness. I have 4x 4.5-9w bulbs in my current 16x24 and mostly use only one at a time alone, sometimes two if it is the two of us. Way low draw. It will also charge phones, etc, usb port stuff without much drawdown. Mine are 12v inverted to 120vac tho I did run some 12vdc MR-16 bulbs early on with a bat inside. Two sets of wiring was a hassle. I dont know how stepping down your 48v to 12v will affect your ah's, should think there will be a bit of loss. Find out and compare that against getting a small pure sine wave inverter from 48v to 120vac. Id like to see how it works out.
Note that batteries charge slow on generators, Id try bringing both fully charged and swap when needed, your low use may get you through; keep some notes on what you can run for how long to get a sense of it.
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Birdman
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# Posted: 4 Feb 2021 01:38
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Good to hear about the foundation! It definitely sounds like that's a good way to go so I'll talk with my buddy when we go out there to do some preliminary clearing and flagging to get his input.
Yea I lucked out on these batteries. Unsure on the chemistry, but they cost $80 a piece and were brand new. One of those insane Walmart clearance deals. Never ended up getting an actual bike to go with it, but figured I would find a use for them eventually.
As far as lighting goes, I think I'm going with all low voltage led. There are these cool recessed ones that I've seen used in a number of van builds:
https://m.aliexpress.com/item/4000124854797.html
They only draw 5w of power. I'm not great with calculating battery hours, but taking into account the 20% safety buffer with ~520wh and running a few of these I should have plenty of run time I hope. I also do have 300w of solar panels available, not sure how effective they will be on my property though because it is pretty wooded and we don't get a ton of sun anyways. I'll tackle the solar later and make due with the generator and bar for now.
And 2 of these wireless dimmer setups so I can set up a few different zones of lights and simplify the wiring process.
https://m.aliexpress.com/item/32968148329.html
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Brettny
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# Posted: 4 Feb 2021 05:44
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Have you talked to the local building inspector/town/county about what your planing?
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ICC
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# Posted: 4 Feb 2021 09:05
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Quoting: Birdman Unsure on the chemistry,
E-bike batteries are usually the cylindrical lithium-ion type, as used by Tesla because they are the most energy-dense of all the lithium types. Probably 52 of the 18650 cells in a 13S4P configuration.
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gcrank1
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# Posted: 4 Feb 2021 10:41
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What usable 12v ah's do you figure can be converted out of those 48v bats?
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ICC
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# Posted: 4 Feb 2021 10:57
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Quoting: gcrank1 What usable 12v ah's do you figure can be converted out of those 48v bats?
How efficient is the converter?
How deep are you willing to discharge the batteries?
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snobdds
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# Posted: 4 Feb 2021 11:04
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Quoting: Birdman Yea I'm still not entirely sure on what foundation to go with.
Stick with your initial thought of sonotubes. This will also get you off the ground a bit. In snow country, you want to be off the ground a little bit. I'm in deep snow country and I'm 3 feet off the ground, best decision I made.
Also, since your in snow country, and use it in the winter to dry things out...get a wood burning stove.
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Birdman
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# Posted: 4 Feb 2021 11:14 - Edited by: Birdman
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Quoting: Brettny Have you talked to the local building inspector/town/county about what your planing?
Yea... I'm a bit obsessive when it comes to researching things and have dug through my county's building code as well as looked at how others have built similar cabins. So first off, I will acknowledge that I am not technically allowed to live in the cabin even recreationally. But after reviewing a number of code appeal cases, it looks like the loophole around here is 2 things: structure has to be under 200 sqft, and if there is no primary dwelling on the residence than you have to refer to the structure as an "agricultural or forestry accessory structure". It's a grey area to say the least, but again based on my code appeal research and seeing what others are doing I feel confident this will work. Also worth mentioning that my property is the last privately owned parcel before hitting national forest land. The parcel is a pretty odd shape @ 90'x500', with the long side having road frontage. Hoping that I can tuck the structure back a bit and maybe install some privacy fencing to get away from prying eyes.
Here is a link to one of the code review appeals I am referring to.
And here are a few other examples of people who have done something similar:
The last guy is right down the street from me, and I actually called him up to talk about his build. Super friendly guy, and he told me that he actually had the building inspector out there and got the thumbs up on everything.
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gcrank1
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# Posted: 4 Feb 2021 11:19
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Fwiw, my infrared lp wall furnace dried out my wet gloves just like my wood stove.
Sitting in front of it feels just like my wood stove.
Takes up LOTS less space than my wood stove.
Fires up and starts kicking out heat right away.
Requires no hole in the roof or class A chimney.
Im getting very attached to it.
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Birdman
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# Posted: 4 Feb 2021 11:28
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Quoting: ICC E-bike batteries are usually the cylindrical lithium-ion type, as used by Tesla because they are the most energy-dense of all the lithium types. Probably 52 of the 18650 cells in a 13S4P configuration.
Yup I believe you're spot on there.
Quoting: gcrank1 What usable 12v ah's do you figure can be converted out of those 48v bats?
Quoting: ICC How efficient is the converter? How deep are you willing to discharge the batteries?
The converter is supposed to be right around 98% efficient, it's a solid state charger so no moving parts or anything. So please check my math/logic here, but since it's a 48v x 13.5ah battery, assuming 100% capacity I should have 648 wh in each battery. Haven't decided on a discharge % yet, but for the sake of discussion let's say super conservative and I'll only discharge down to 80%, so ~520 wh. So again please correct me if I'm off here, but between these two batteries I essentially have the same capacity as a Yeti 1000 lithium @ right around 1 kwh.
My ultimate goal is to run a few of these low voltage LEDs, the diesel heater as needed, and one of the small and super efficient compressor style refrigerators like Dometic that are popular amongst the van conversion crowd. The batteries charge @ 2A, so they should take about 4-6 hours to fully charge. I wonder if I can squeeze a day's worth of use out of each battery without any inputs? We'll have to see.
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Birdman
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# Posted: 4 Feb 2021 11:35
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Quoting: snobdds Stick with your initial thought of sonotubes. This will also get you off the ground a bit. In snow country, you want to be off the ground a little bit. I'm in deep snow country and I'm 3 feet off the ground, best decision I made. Also, since your in snow country, and use it in the winter to dry things out...get a wood burning stove.
Yea good point. This year has been very good to this area and there's hardly and snow on the ground, but other years it could have 5'+ easy.
I actually do have a small wood stove that I COULD install too, but I'm really hoping to rely on the diesel heater as a primary heat source because it's so damn convenient compared to maintaining a small wood stove.
Here's the stove that I have
Quoting: gcrank1 Fwiw, my infrared lp wall furnace dried out my wet gloves just like my wood stove. Sitting in front of it feels just like my wood stove. Takes up LOTS less space than my wood stove. Fires up and starts kicking out heat right away. Requires no hole in the roof or class A chimney. Im getting very attached to it.
What's the relative humidity typically where you are at? Those look very similar to Mr. Buddy style heaters to me (maybe I'm totally wrong there, but it's an unvented propane heater right?), and I used those for a while in my short bus conversion. Just didn't work out in my climate. After 4 or so nights my down sleeping bag lost enough loft from the moisture that it wasn't keeping me cold.
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Birdman
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# Posted: 4 Feb 2021 11:40
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Also huge thank you to everyone who's responded! Didn't expect this forum to be so active. Super helpful to have people like yourselves to talk this stuff out with. I've been living in my own head with these ideas since I purchased the properties back in June of last year.
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Brettny
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# Posted: 4 Feb 2021 11:40
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I would also look up any setback requirements for a building 90' with 500' of road frontage dosnt leave much room for error nor does it give you alot of space from the road to tuck it away.
Sorry not going to download anything from an unknown source.
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snobdds
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# Posted: 4 Feb 2021 11:51
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Quoting: Birdman I actually do have a small wood stove that I COULD install too, but I'm really hoping to rely on the diesel heater as a primary heat source because it's so damn convenient compared to maintaining a small wood stove.
Wood stoves work off radiant heat. Diesel and propane work off of convection heat.
You could run a place all day off the propane or diesel and it will never feel warm as none of the indoor furnishings will get warm. It will always feel cold on surfaces. A wood stove heats the objects in the room and for cold snow gear, you want them to dry thru, just not surface dry.
I also have a place in Steamboat since I snowboard a lot in the winter, it's all radiant heat. I actually ripped out the forced air furnace and had a geothermal well drilled and had hot water baseboard heaters installed. The comfort now is night and day different than when it was just convection heat.
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Nate R
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# Posted: 4 Feb 2021 12:00
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Birdman, there are vented propane heaters that don't release any moisture to the interior space. RV Propane heaters are like this, but as you said, they can suck the power. Propane wall furnaces are usually vented outside, too. The wall mounted non-vented ones are the moisture nightmare.....You actually get 1.6 lbs of water in the air for every pound of propane burned!!!
URL
If I were you, I'd sell the diesel heater and get a direct vent propane wall heater, like a Martin 14000 BTU. Just my opinion.
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Birdman
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# Posted: 4 Feb 2021 12:12 - Edited by: Birdman
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Quoting: Brettny I would also look up any setback requirements for a building 90' with 500' of road frontage dosnt leave much room for error nor does it give you alot of space from the road to tuck it away. Sorry not going to download anything from an unknown source.
Yup just looked into that recently. Setback from the back lines are 5'. I'm not so worried about it being 100% unseen, because after talking with the other property owner mentioned above they got the thumbs up from building inspectors. It's more about privacy.
Totally hear you on the file, if it makes you feel better that's a PDF coming straight from my county's website. You can google site:www.kingcounty.gov "Code Enforcement Appeal" "5581700120" and you'll find it.
Or I can make it easy on you. Here's the quote from that case:
"The use of the onsite structures for residential occupancy, whether merely recreational in nature
on a temporary basis or permanently, is not allowed under the zoning code.
In order to be permitted to remain onsite, the accessory structures must be utilized as solely
accessory to a permitted use;. as residential use is not feasible on the property due to sanitation
limitations, they are not able to be utilized as residential accessory structures since no primary
residence is feasible on the property. As a result, as noted the Appellants have acknowledged
that they may only use the structures in conjunction with a primary agricultural or forestry
production use for storage of materials used onsite, and state that they intend to use the property
in such manner. Such intended use would resolve the code violations on the property so long as
the structural size is exempt from building permit requirements."
It's a common theme when looking at these code appeal cases; you have to use the right wording when describing your structure and be careful to not mention anything like "cabin" or "tiny house". I am also lucky that my parents live in the area, so if I do end up living here full time I can use my parents address as my "full time" / mailing address.
Quoting: snobdds Wood stoves work off radiant heat. Diesel and propane work off of convection heat. You could run a place all day off the propane or diesel and it will never feel warm as none of the indoor furnishings will get warm. It will always feel cold on surfaces. A wood stove heats the objects in the room and for cold snow gear, you want them to dry thru, just not surface dry. I also have a place in Steamboat since I snowboard a lot in the winter, it's all radiant heat. I actually ripped out the forced air furnace and had a geothermal well drilled and had hot water baseboard heaters installed. The comfort now is night and day different than when it was just convection heat.
Great info! I didn't know this at all. Ok... well sounds like I need to plan on incorporating this little wood stove into my setup. It'll definitely add to the ambiance, and that'll be good to have both heat sources so I don't have to rely on such a small wood stove alone to keep me warm through the night.
I'll look around, but do you have a thread on here for your cabin that I could check out?
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Nate R
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# Posted: 4 Feb 2021 12:20
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How does that mean you can build what you want?
"they may only use the structures in conjunction with a primary agricultural or forestry
production use for storage of materials used onsite, and state that they intend to use the property
in such manner. Such intended use would resolve the code violations on the property so long as
the structural size is exempt from building permit requirements "
I read this as they can only use a small building with no residence on site for storage...?
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Birdman
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# Posted: 4 Feb 2021 12:25
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Quoting: Nate R Birdman, there are vented propane heaters that don't release any moisture to the interior space. RV Propane heaters are like this, but as you said, they can suck the power. Propane wall furnaces are usually vented outside, too. The wall mounted non-vented ones are the moisture nightmare.....You actually get 1.6 lbs of water in the air for every pound of propane burned!!! URL If I were you, I'd sell the diesel heater and get a direct vent propane wall heater, like a Martin 14000 BTU. Just my opinion.
Experienced the propane moisture issues first hand while camping in my short bus up at the mountain. Haven't seen that Martin heater before, it looks like it could work really well, but MAN they cost right around $1000! My diesel heater cost right around $100. It is cool that it requires no electricity so that's a plus, but besides that I don't see what benefit it provides above my diesel heater. If I end up finding that my batteries don't have enough juice to keep the things running that I need, I'll consider those vented propane heaters more seriously.
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Birdman
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# Posted: 4 Feb 2021 12:28
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Quoting: Nate R How does that mean you can build what you want? "they may only use the structures in conjunction with a primary agricultural or forestry production use for storage of materials used onsite, and state that they intend to use the property in such manner. Such intended use would resolve the code violations on the property so long as the structural size is exempt from building permit requirements " I read this as they can only use a small building with no residence on site for storage...?
You're not wrong, but I have driven by the property mentioned in that code appeal case and they are definitely still using it as a cabin / recreational property. And after speaking with the other property owner down the street from me, it's clearly a cabin and not used for the accessory use described, but the building inspector gave him the thumbs up and he hasn't had any problems. His property is right out in the open too. I have found ~15 other examples of people doing this same thing, and most of them have no code enforcement complaints against them.
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snobdds
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# Posted: 4 Feb 2021 12:29 - Edited by: snobdds
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Quoting: Nate R I'll look around, but do you have a thread on here for your cabin that I could check out?
I was not very good about updating it. here is a finished product. 
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Birdman
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# Posted: 4 Feb 2021 12:41
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snobdds that thing looks amazing!! Wish I could build something bigger like you've got there. The geothermal well is so rad too, great use of the natural resources to make your place more comfortable.
If you're ever in the PNW and want someone to show you the goods, give me a shout. I've been riding at Stevens Pass since I was 4 years old so I've got the place pretty well mapped out.
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snobdds
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# Posted: 4 Feb 2021 13:00 - Edited by: snobdds
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Quoting: Birdman snobdds that thing looks amazing!! Wish I could build something bigger like you've got there. The geothermal well is so rad too, great use of the natural resources to make your place more comfortable. If you're ever in the PNW and want someone to show you the goods, give me a shout. I've been riding at Stevens Pass since I was 4 years old so I've got the place pretty well mapped out.
I just built it. I didn't ask for permission or what codes needed to be followed. THe old, it's easier to ask for forgiveness than permission. I did have to have the place rezoned so I could pay more in taxes, but they don't do code stuff here.
Sounds good. The first time I heard of stevens pass was in a snowboard movie called easy rider. To this day I can rember temple cummings jumping the moving train. It looks like good terrain up there. I go to whistler every few years. The snow is so much different than what I am use to, very heavy wet snow. I am use to the champagne powder of Steamboat.
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Birdman
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# Posted: 4 Feb 2021 13:16
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Quoting: snobdds I just built it. I didn't ask for permission or what codes needed to be followed. THe old, it's easier to ask for forgiveness than permission. I did have to have the place rezoned so I could pay more in taxes, but they don't do code stuff here. Sounds good. The first time I heard of stevens pass was in a snowboard movie called easy rider. To this day I can rember temple cummings jumping the moving train. It looks like good terrain up there. I go to whistler every few years. The snow is so much different than what I am use to, very heavy wet snow. I am use to the champagne powder of Steamboat.
Love it! Yea I wish I had the acreage to do whatever I want and a code department that was a little more lenient, but I'm glad that they at least allow what they do around here. The other cool thing is that there is no limit to the number of accessory structures on a property, so I can build multiple of these little cabins if I find I need the space down the line.
Stevens is awesome man. I haven't seen Easy Rider, but I'm a huuuuge fan of Temple Cummins and all those OG PNW snowboarders. Highly recommend this video too, it does a great job of highlighting the terrain here. Just like you experienced at Whistler, it's heeeeavy snow out here. Most of our big storms come in and temps are right around freezing and the snow is ruined within hours a lot of the time. But when it's good, it's so good. Definitely makes it hard to plan a trip though. I've ridden here basically my whole life and haven't yet had the chance to experience the champagne pow of the Rockies... once I get this cabin set up I'm hoping to do a lot more cruising around to other resorts with my bus.
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gcrank1
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# Posted: 4 Feb 2021 15:02
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Some may have noticed I said 'infrared' lp heater. Unlike the 'blue flame' heaters, which do heat the air, and air is a poor conductor of heat, which then floats around the room eventually raising the temp of objects in the room the infrared heats objects. Yes, there is a convection process included, just like there is with a wood stove too.
When we run the wood stove we typically have a large mouth jug of water on it for humidity and ready use hot water. With the lp it is humidifying as is. Our shack is air leaky enough that the O2 alarm never goes off. I was using the lp for initial warm up (and right away) and getting the wood stove up to speed but the visit last Sat we just ran the lp and had the 16x24 from 24*f to 76* in two hours, quicker than my combo method. I think the wood stove was drafting my warming air in the cabin thru the stove and up the stack.
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gcrank1
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# Posted: 4 Feb 2021 15:30
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Regarding your bike-bats math it looks right but I dont have experience with more than 12v bat-banks so that 48v converted to 12v may be throwing me.
I get the same 48v x 13.5 ah = 648w
x 80% use (and including in that the -2% effic.drop)
is the 520ish w. Now with that divided by 12.5v converted makes for 40ish ah per bat, 80 total usable, IF Im doing this correctly??
Guess that fridge is 12vdc?, some 7.5amps? or? My old absorption cooler is this so I'll use it as an example, if it were 7.5amps you would run the fridge only for 10ish hours. For me that is too high a tariff on my bat-bank so we use an ice cooler. Not a Yeti, but similar (and faarrr cheaper) and used wisely lasts for days. Key for me with bat-bank based power, no matter how it is charged or converted or inverted, is energy conservation first and the new-gen ice chest suits us (and is way cheaper) than a power sucking fridge.
Ie, up your power 'requirements' means upping your system (costs) to accommodate the indulgences. Running the numbers, if we go from a 3amp/hr av. usage (3x24hrs=72 x 3 days=216ah @ 80% dod LFP means I 'need' a 270ah battery; thats pricey for only an av. 3amp draw. Make it 6 and  )
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