12x12 Tiny Cabin Build - 2023

Started by Adam Roby, March 15, 2023, 08:34:18 AM

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Adam Roby

I've decided to build a small cabin this summer, with the eventual plan to dismantle the old cabin and possibly replace it with a 3-walled lean-to tractor port of sorts.  The old cabin fell into some rough times during COVID.  Because of the border closure, I was not able to tend to it for close to 3 years, and racoons managed to get in and destroyed the place.

The new build is small, some may consider it just a shed, but I want it to be my tiny home away from home. 
I plan on wrapping it with chicken wire before the siding and roofing, as well as the perimeter of the floor and under the floor.  I will also be adding 1/4" mesh steel around all soffits and vents, to hopefully deter the mice as much as possible, and keep the racoons from destroying this building as well.  I am building this alone with no access to water or electricity, and it will be completely off grid.  As such, I will be building it a bit non-standard in that I will make 4' wide wall sections at home in my garage, which will fit in my 4x8 trailer, and assemble them like Lego at the build site.   I am hoping I can get it dried in before the end of summer, considering I have other commitments which can take up some weekends (family, cottage we rent out, hunting season, etc.).

I will be using 9 foundation screws, and step one is just making sure I can screw them into the land.  That process should start as soon as the ground is defrosted enough to get started.  I've already purchased them, so I am committed now.  I have to say, SketchUp is a fantastic tool to plan these kinds of builds.  You run into so many virtual issues that you can address and modify now before the build even starts.  I think my plan makes sense now, and I have almost everything detailed and measured out, as well as the materials and costs calculated.

I was originally going to have the main beams lie directly on the foundation screws to avoid any kind of pivot points, but I need to keep access under the building to insulate in the future, and I believe it will help keep the critters out.  All supports will include 3/4" plywood gussets over the supports in all angles, which should help mitigate any lateral movement.  Being a small building, it should be easy enough to keep level.  I will post more images as the build starts.

Not sure on colors yet, but I did this as a test to see how it might look (vinyl siding with metal roof).



Is it possible to change the design to use foundation screws along the two eve sides with no central ones? That's just my preference for minimizing how much crawling under the building I might need to do in future years.
Just because something has been done and has not failed, doesn't mean it is good design.

Adam Roby

Do you mean if ever I need to level the building?
6 screws would probably be sufficient, but I am a bit skeptical of the 5000 lb claim of the foundation screws.  
My thinking was that the center one would be the fixed one that is never adjusted, and I would use all the surrounding screws for the adjustment, thereby removing the need to crawl under (it is a grid of 3x3, 8 are on the perimeter with only one in the center.  I would also have to beef up the main beams to support a 12' span instead of only 6.  Do you think my logic is flawed there?  It is definitely not too late to change the plans.

Adam Roby

I slept on it, and realized you probably mean just the center beam can changed, keeping all outer beams the same.  That would mean 8 foundation screws instead of 9, and only the center beam can have a larger size.  In reality, the perimeter is where all the weight should be, and the center screw will only really deal with floor bounciness...  I will do some more drawings today, thanks for the suggestion,


All the weight (not a whole lot of it) goes to the to eave walls. At 12' your floor doesn't need a center support just some 2x10s or 2x12s, all 3 of the center screws aren't necessary - as long as you're doing joists and rafters.

They make marine boat woodstoves that would be perfect for a little space like that.

Just my opinion, you could lay down some solid CMU blocks and frame right on those. If the building moves its light enough to jack up with a car jack and shim.

I would consider framing the entire floor and subfloor with pressure treated. Insulate on top of the subfloor with 2"XPS. Anything underneath will turn into nest material for animals, I think.

Adam Roby

Quote from: NathanS on March 16, 2023, 07:40:17 AMI would consider framing the entire floor and subfloor with pressure treated. Insulate on top of the subfloor with 2"XPS. Anything underneath will turn into nest material for animals, I think.

I was contemplating that when the floor would have been much closer to the ground (had I left the beams lay directly on the foundation screws).  Since moving it up, I should have 18-20 inches above ground, and I seem to remember one of the Don's mentioning that was a safe zone for non-treated.   The only insulation I plan on adding is spray foam, I wonder, could that be used as nest material?  I was also concerned having pressure treated on the floor (off-gassing), since insulation will only happen in 1-2 years, and I will be using it in the meantime. 

Blocks are also difficult for me as I have a bad back, after my last surgery my doctor advised against any heavy lifting.  I tend to work like a madman for 16 hours straight, then have to lie on a sofa for 2 weeks to recover.  That was also driving the foundation screw idea.


I believe 18" is the separation needed to use non PT lumber.  

I just had the floor of my cabin spray foamed, we did 2".  Amazing the difference it made, highly recommend.  For a small occasionally used cabin I don't think you need any more than 2".  And I don't see how animals could get into it, but I guess I'll have to report back on that.


I'm not sure about the spray foam. Before I enclosed the eaves on my house, starlings would dig into and nest in the polyiso insulation. It's incredible the damage animals can do. Chipmunks actually chewed through the wood after it was enclosed and I believe they nested in it too.

Adam Roby

Quote from: NathanS on 3/16/2023, 8:40:17 AMThey make marine boat woodstoves that would be perfect for a little space like that.

I remember seeing someone with one of those on here a couple years ago.  It was a very attractive unit.
I was leaning more towards a small direct-vent propane heater.  They sell the 11,000 BTU units at a decent price.  They also take very little room, which helps in such a small structure.  Still haven't decided though.

Something like this:

Adam Roby

If I went with the recommended 2"x10" without center beam, would the supported ends need to be double up, or could they be like this?



By the book, I believe you would want to use the spans for table 602.7 "Roof, ceiling and one clear-span floor"

A doubled 2x10 can span 6' 1" in 50psf snowload.

Alternative would be to add another screw to shorten the load bearing wall span.

Adam Roby

Well, this project took a quick halt.  First I broke a rib and was out of commission for 3 weeks, then I had a talk with the code encorcer who has a different take on the NY state restrictions.  The city wants a permit for anything over 10x10, not 12x12.  The other caveat is that any structure that will get insulated immediately becomes a dwelling, which means the screw in pylons are no longer legal to use.  The inspector wants to see the externior walls from inside, and from any window.  Basically, if you decide to insulate your outhouse, it then requires a cement foundation.  I understand the safety concern for anyone trying to build a residence, but this will be slept in maybe 3 times a year.  There will never be any water, plumbing, or electricity inside.

Not sure what my next move should be.  I can't afford to put in a full foundation for a building that will cost me $3000 build.  I also can't move around cement blocks or pour concrete footings with my back.   It's either a shed that will forever look like a shed, or it doesn't happen at all.  


Years ago there used to be a special category for "hunting and fishing" cabins. No permanent foundation was required and piers were allowed. I have no idea about how insulation was looked at. No plumbing indoors and no grid tie electric or other services were allowed IIRC. I believe there were other reduced structural requirements as well as a limit on the number of days a year it could be used. I have no idea if such things are still on the books or if that was state-wide or county-specific or whatever. 
Just because something has been done and has not failed, doesn't mean it is good design.

Adam Roby

Indeed, they still have some special provisions for a hunting cabin, where no water in or out, and no electrical will be installed.  The existing cabin has grandfathered in rights for the blocks it sits on now, but if I were to rebuild they would want footings below the frostline with rebar etc. and she'd prefer I deal with a contractor she's worked with before to avoid me having to fail inspection.  I will still ask for a couple of quotes to get an idea of the cost, but I have a feeling it will be pricey... unless they hire students to dig with shovels to avoid the big machinery.  Any stabs at what they may charge for footings for a 12x16 cabin (as long as I am spending more, may as well consider x16 instead of x12.  What would code be for that, 6 footings, 2'x2' pads 48" deep kind of thing?  Is it realistic to dig something like this by hand?  I sure would prefer a new building over patching the old one.


Is she saying that you could or cannot do a special hunt/fish cabin but that id you did one of those you'd still need a rebar-reinforced footing?

A typical pier type of foundation as seen with a large number of DIY cabins will not meet the specs as set out in the IRC, which is used by most states. The norm usually includes a full perimeter frost depth steel reinforced concrete footing or a frost depth footing combined with a slab, often as a monolith.

The best answer should come from the department issuing the building permit.

IRC, Chapter 4 Foundations
Just because something has been done and has not failed, doesn't mean it is good design.


Quote from: Adam Roby on May 08, 2023, 10:27:35 AMshe'd prefer I deal with a contractor she's worked with before to avoid me having to fail inspection. 

Unreal. Just wow on so many levels.

I don't know what advice to give but a code inspector threatening to fail inspection on your non existant building in the middle of nowhere northern New York if you dont use her contractor is just perfect.

You have spent a lot of money trying to vacation in this state with not much but headaches and an empty wallet to show for it. In my opinion, build the 'shed' and enjoy it during hunting season if youre crazy enough to still want to come here. If they actually come after you, burn it down and leave this absurd state and count yourself lucky.


Yeah I'm sorry to hear you're going through this, I'd probably do it the way you want, and then once some time has passed and no visitation from her finish it to your liking.  It sucks to say that, but obviously there is some strange things happening up there.  I know things are handled much more reasonably where I am in NY.  

Adam Roby

Sorry for the confusion Don.  The existing cabin had the hunting cabin rights and was built with blocks and no water.  It actually did have electric at some point, and is completely insulated.  Those rights are grandfathered if I can rebuild it, but even that I think I may get the run-around.

Latest conversation I had on Friday with the code enforcer is that I am not allowed any side longer than 10', so max of 10x10 means no 8x12 either. I called a few places, and they estimate a 12x16 perimeter footing would cost around $3000, if that even passes.  Everyone is booked until August at this point.  I think for this year, I will simply build the 10x10 to have somewhere to store my stuff, and worry about the next decision once that is done.  


Ah. I understand.  Frustrating on the size/side lengths.

We've met with the NRCS... a federal conservation assistance program ($ grants) and are also frustrated by some of their rules, stipulations and methods.
Just because something has been done and has not failed, doesn't mean it is good design.

Adam Roby

Side tracking the build for a minute...

This may seem like an odd idea, but I wonder if this is a valid truss type of design?

The existing trusses in the old cabin were done very strangely.  They are spaced 4' apart, and use 2x4 across them.

There are 2x4's running the width with presswood on top and on bottom.  Then it looks like a 2x6 (not nailed or connected) with a cutout to support the "ridge beam", but the rafter 2x6's are resting on top of it, and simply nailed side by side.  Same kind of connection at the soffit ends.  It's very strange, but has been abandoned 30+ years that I know about and it still very straight (just the roof sheathing is failing).  If I were to try to fix this, I was thinking to put a new truss system every 4' between the existing ones, then remove the existing one by one while replacing them with the new design.  I'd like to eliminate the attic space which seems to attract the raccoons.  I put a 2x6 tie across at about 1/3 the height down (not sure if it should be 1/3 up).  If I add plywood gussets on the riser and truss connection up top, would these be strong (at least as strong as what is there)?  I don't trust the ridge beam that is there, it is several pieces nailed together to make a longer beam.  Just moving the plywood underneath it makes the supports holding it up move, so I need to strategically cut the plywood around those supports to get rid of the attic space.  As you can see, it's full of garbage and crap up there, from the previous owner and scattered around from the racoons. 

I know tear down and rebuild would be the right decision, but I am still considering this due to all the nonsense around the permit process and grandfathered rights.  I am starting the 10x10 build first, so I have time to plan out how and if I can fix the existing cabin. 

Heading down tomorrow to layout the placement of the now 10x10 build.  I worked a bit on Friday to remove some trees and an old camper trailer that was in that spot.  Hoping to at least get one or all of those foundation screws into the ground.  I have no clue what the ground is like.  I know the top layer is very soft, everything sinks (tractor, trailer, cabin on blocks) over time. 


A quick reply, then I may be able to get back here later today or tomorrow.

What you have illustrated in the drawing is not a truss. It is an incomplete rafter set. The horizontal member, near the top, would be a collar tie. To complete the rafter set one would have to add a rafter tie in the lower 1/3 of the triangle.

The collar tie helps to hold the top ends of the rafter pair together, and the upper end of the rafters would be nailed to a ridge board that runs lengthwise under the roof peak. The upper rafter ends would be cut at a suitable angle to the roof's pitch, in pairs against the ridge board.

The lower horizontal rafter tie is to resist the outward forces created by the loads on the roof. Rafter ties would usually be positioned on the wall tops and face nailed to the side faces of the rafter tails which are notched (birdsmouth) to provide a flat bearing surface on the horizontal 2x4(6?) that should be nailed across and to the top ends of the wall studs. This is the wall top plate and there would normally be two, one on top of the other with the topmost ones overlapping the lower at the corners to tie the upper ends of the walls together in a box shape. Rafter ties can be raised as long as they are in the lower 1/3 of the rafter triangle. There are size adjustments to the rafters of the rafter tie that may be required as the height of the rafter tie is raised.

What the photograph shows could be called odd DIY construction. The fact that the structure still stands is a testament of sorts to the resiliency of wood building materials even when assembled in a less-than-ideal manner. The existing rfater ties (doubling as ceiling joists) kept the walls from spreading. The ridge did not sag because the wall tops were held in place by the rafter ties.

Question.  How much can be removed and replaced with new materials before the rules would consider the work to be something that is NOT grandfathered in?

Note, when building rafters that meet code the rafter spacing would be 16, 19.2 or 24" on centers (OC) usually 16 or 24). Tables or a rafter load calculator would be used to determine that. The collar ties would be no more than 4 feet apart.
Just because something has been done and has not failed, doesn't mean it is good design.

Adam Roby

Quote from: MountainDon on May 21, 2023, 02:47:44 PM... How much can be removed and replaced with new materials before the rules would consider the work to be something that is NOT grandfathered in? ...

 That is a good question, and one I don't want to ask the city.  The way it seems to work here, is as long as you get a permit for what they can see, then they are happy.  They don't charge much for the permits themselves, I think it is more so they know when to raise the taxes and I guess keep some control.  If I can do some reinforcement work inside, then simply get a permit to replace the roof (sheathing and metal over top) then I think they'd be happy enough.  There is literally nothing inside but framing and presswood, so even if I replace it all, they'd have no way of really knowing (no finishing or anything).  

If the rafter ties can be 4' OC, I can possibly remove the other 2x4's that span the area to open it up, while reinforcing the existing truss system and adding extra trusses in between the existing ones.  I'd like to at least add gussets over the existing setup, and beef up the ridge board.  I would lose some of the support on the outside walls...  would doubling up the ties on the 4' OC have any added benefit?  (2x 2x4 every 4' versus 1x 2x4 every 2')  I am thinking more esthetics and extra room to put the vertical supports for the ridge board. 

Adam Roby

Hopefully this drawing helps explain what is there now, and how I would like to add to it (the incomplete rafter above should make a bit more sense with this drawing).

This is how it looks now.

This is what I am thinking to do.  Everything existing is now semi-transparent grey.

Removing every 2nd 2x4 across the structure to open it up, but adding a new one on the side of the existing to help support the offset rafters since they are only nailed together at the top.
Adding two new 2x6 vertical supports for the ridge board.
Adding new rafters in between the existing, but without the bottom chord to keep it all open.
Adding the 2nd tie across the top to create some "attic" space for ventilation. 

Adam Roby

Well, begun the 10x10 build.  As per tradition...

Silly floor dance.   Funny, the 4-wheeler was sitting funny, which made the camera not very level, looks like the floor is lopsided,  but trust me, it is perfectly level all around.  Dug down as much as I could until I hit rock, then filled the holes with rock and rock dust, topped with 18"x24" "patio" stone, and then those deck posts.  Best I could do, the foundation screws would not go deeper and 12", too much rock, even digging  by hand 2' down, so much rock it was impossible.  


If I was at home I would rotate that image to make the platform level. But I don't have that ability on my phone.

As for depth, if there is rock, there is rock. Better than sand.  :)
Just because something has been done and has not failed, doesn't mean it is good design.