You may want to include "gabions" in your foundation planning.  I have no direct experience, but see them employed often.

Thinking about doing a gravel trench for a 10x16 shed in NE Minnesota.  Something like this, two trenches of crushed rock to place blocks (to get it up off the ground a bit) and then the beams sit on the blocks.  Building would be modified 10x14 Little House plans from this site.



I wouldn't be going below the frostline, just down to solid ground, and drained to daylight.  Would line with filter fabric to keep sediment out. Also thinking about putting in a perforated pipe to drain water more easily.

This is sort of a hybrid of different shed base ideas I've seen: the gravel trench described in the Little House plans kit, the commonly used gravel pad shed base (typically bordered with treated timbers) and the rubble trench (typically full perimeter trench with concrete grade beam).

We actually already have a base of class 5 on the build site, and some folks said we could just put blocks on top of that.  Which I've considered, but the shed spot is sloped about 12" from high to low corners and I didn't like the idea of a stack of 4-5 blocks on the low side. So the trenches would be dug down about 10-12" on the high side, and the low side we'd be building up mounds of class 5 to hold in the crushed rock and grade away from the building.

Is this a dumb idea and/or is there a better way to create a shed base on a slope like this?  We'd like to be able to shim and adjust as needed, so piers or posts don't seem like they would work.   Oh and we have sticky red clay, as far down as we've been able to dig.  Our neighbor said his well driller told him he's got 145ft of clay.

Thanks in advance for any advice!

It seems best to start planning from the ground up; footprint and foundation. We will be deciding between 12X16 and 14x14. 

My wife has a thing for symmetry and since our walls will be around 14' high, I too see a pleasant little cube taking shape. A 14' tall 12' wide box seems tipsy by comparison. Additionally, a 14' span could open up more head room upstairs without increasing the pitch. Still, I wonder if there isn't a savings to be found in lumber spanning a 12' rectangle. We've been playing with scale cutouts of furnishings and appliances on graph paper to determine if one shape footprint or the other has any functional advantages.

Regarding the foundation, we're building in an expedient location right now. We can drive almost to the spot and it's close to the electric bush (the in-laws cabin). The plan is to build on skids so we can drag it to a permanent location eventually when we decide where.

I'm seeking advice on the appropriate foundations to go under the skids.  They have to satisfy some pretty unique conditions.  The shack will need to be lifted fairly high off the ground.  A few years ago a one hundred year flood and a log jam in the right wrong place upstream drowned the property 16" deep. Our frost runs deep and the ground water is high. Also these are temporary footings and we don't want to put too much expense into them unless we would be able to reuse them in the future. 

I have an idea to build piles out of gabion. One thing the land seems to provide in profusion is rocks. Dig a 2 cubic foot hole and you somehow end up with a foot of dirt and 2 feet of river rock. My idea is to dig a hole for a pier, build a hoop out of galvanized sheep panel, wrap that in a sock of landscape fabric, drop that in the hole and fill with rock, and backfill around it. Top that all off with a concrete tile to shim off of. Please feel free to explain how dumb this idea is in the comments!


Lastly, the property can experience some exceptional winds and while I understand generally what it will take to hold the shack up, I don't have a clue what it will take to hold it down...

Hey Gang! I've been doing cabin-curious internet searches for awhile now but I'm surprised and delighted to have just now found this community! I've clicked around a bit now and it seems like there is a ton of useful and knowledgeable advice. I also appreciate the user positivity and enthusiasm. I sincerely look forward to gaining your valuable insight and sharing our building experience.  

A year ago my wife's parents gifted us a couple acres on the backside of their place. They are selling their parcel and the existing cabin soon, so we've been developing an idea to build a livable off grid shack so we can continue to visit after they leave. It's about a 4 hour drive from where we live, but we try to get over to the land about every three weeks and we seldom get to stay for more than 3 days at a time.

In the area we are building there isn't much in the way of code enforcement, but in any case we can build up to 200 sf without a permit. We are planning an off grid 1.5 story 14x14 or 12x16 with a 3/4 bath, full kitchen, and a wood stove. We haven't settled on a design theme yet, but the area has lots of cool agricultural, mining, railroad, and forest service buildings to draw inspiration from.

As much as possible we would like to build in security. Most of the time the building will have to look after itself. It will need to stay dry and clean. It will need to keep out insects and four legged critters from mice to black bears. It also might have to fight fires and endure floods on it's own. It would also be nice to have some design adaptability should we decide to build a larger permitted house in the future and then bolt this one onto it.

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. 

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. 

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.

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. 

For those thinking about getting a grapple, here's my take on the LS grapple I bought and you get to see more cabin stuff