You'd typically use a birdsmouth at both ends of a shed-roof rafter so each end has a proper seat on the top plate. On the tall wall, it's still the same idea - the rafter gets a plumb cut for the wall line and a seat cut so it bears flat on the plate instead of just hanging off the face of the wall.

A couple things to watch:

• Don't overcut the rafter for the birdsmouth.
• Make sure you have enough bearing on both plates.
• Add the proper hurricane ties / metal connectors to tie the rafters down.
• Check your span, snow load, and local code before finalizing the cuts.

If the geometry gets awkward on the high side, some people use a ledger or dropped beam detail, but for a standard shed roof, two birdsmouth cuts is usually the normal approach.

I'd strongly recommend drawing one rafter full-size on plywood or on the floor first so you can test the fit before cutting the whole set.

A 16x36 cabin can work really well for what you're describing, and keeping it 16' wide is smart if you want to preserve the option of moving it later. If mobility is even a remote possibility, I'd be cautious about simple concrete pads/blocks alone for a structure that size. They can work for smaller sheds, but for a cabin you'll want something more stable and frost-resistant, like sonotube piers, helical piles, or an engineered pier system, depending on your soil and climate.

If you want to keep the lot buildable long-term, an elevated pier-style foundation makes a lot of sense and is much easier to remove than a full slab. I'd also think through access for a future move before final placement.

Your layout idea is very doable in 16x36. A main floor with one bedroom, bath, small kitchen, and open living area plus a loft for the second sleeping space would probably be the most efficient. Board and batten with a steel roof would fit the rustic look nicely, and an old cook stove could be a great feature as long as clearances, venting, and floor/wall protection are done properly.
Biggest advice: check setbacks, frost depth, and local code before committing to the foundation. That will drive the best answer more than anything else.

To help clear up the terminology confusion: the reason you're seeing different down payments is entirely about the bank's risk.

• Raw Land Loans (25-50% down): This is for land with absolutely nothing on it.. no roads, no power, no sewer. Banks view this as highly speculative, so they want a lot of your cash in the deal.
• Lot Loans (10-20% down): This is exactly what you are looking at. Because the lot is in a development and already has water, power, and road access, it is considered "build-ready" or an "improved lot." The bank feels much safer lending on this, hence the lower down payment.
  

As for lenders, absolutely skip the national banks like Chase or BofA.. they generally hate land loans. Your best bet is to Google "Credit Unions" or "Community Banks" in the specific Idaho county where the lot is located. Local portfolio lenders actually want to finance local growth and will have the 10-20% lot loan products you need. (Also, Rothbard is 100% right.. read those HOA covenants carefully before you buy to make sure they allow your specific build plans!).

One longer-term tip regarding "improved" lots: If you plan on eventually using this property as a rental or investment (like an Airbnb/STR), keep a detailed paper trail of what you pay for the lot and the utilities/infrastructure.

While raw land itself can't be depreciated on your taxes, all those "land improvements" - like the grading, utility hookups, driveway paving, and fencing - absolutely can be. You can use a tax strategy called cost segregation to significantly accelerate the depreciation on those improvements and save a ton on taxes. I've used SMF Cost Segregation Advisors for my projects.
 The nice thing about them is they will run a free preliminary benefit analysis for you upfront, so you can see exactly what your tax savings would be before you ever commit to doing a full study.

Good luck with the Idaho lot hunt! Stick to the local credit unions and you'll find the financing you need.

Very nice - i am impressed. This is going to be an awesome spot for the family, I am sure 

Great points on the SIPs and slab-on-grade. That combination definitely shaves off a ton of framing time and foundation headaches when you're doing the heavy lifting yourself. Low-pitch asphalt is a smart, budget-friendly move too.
Totally agree on the cost segregation front.. it's a massive cheat code for freeing up cash flow if you're holding the property as a rental or investment. Just need to have REPS status if its a long term rental and of course need to materially participate. 

I saw you mentioned Cost Segregation Guys. I actually looked into them on my last build but ended up going with SMF Cost Segregation Advisors instead. I found SMF's process to be a bit smoother, mainly because they ran a free preliminary benefit analysis for me right out of the gate and I had a pretty nuanced tax circumstance as I needed to do a lookback study. It was incredibly helpful to see the exact estimated tax savings on paper before I had to commit or pay for the actual study and there was some adjustment they did to account for all the depreciation I didn't claim in the years prior.. 

Just throwing it out there as another option for anyone reading the thread who might be weighing their choices on the tax side. Good luck with the rest of the build!

See if this link works for you for: https://app.sketchup.com/app

They've really buried the free version (online only, and limited) but it still works for me when I don't need to export DWG's etc. 

It's been a while  so I thought I would toss out an update.

The foundation which is now about 23rds complete (the new foundation) and is entirely closed in now, has made a HUGE difference to overnight temperature swings and ease of keeping the cabin warm in the winter.  I know, I know, that was obvious but I didn't think it would make THAT much of a difference! ha ha

This spring we plan to finish the last 1 1/2 walls and add the foundation for the addition as well, which will be a 12x18 master and an 8x10 dinning area in an L shape around the East and South walls.  I used to have sketch up but it seems to no longer work and new versions they want you to pay or something....I might have to find something else so I can do a drawing.

We are also planning the first guest cabin which will be a D-log butt and pass style cabin in the 10x12 range.  Bascially a 'bedroom' cabin with a wood cookstove for heat, a bed, some chairs, maybe a counter of sorts and a power station to run things with a place to put a portable solar panel.  That way the power station and solar panel can be brought up when needed and removed when not there, making it secure

Meanwhile, my battle with the critters got a little higher tech

Mountain Don gave great advice.

I have had a Stiebel Eltron for almost 10 years. It runs on 240v and uses three 40 amp breakers. This is one of their bigger units, and in a cold climate. I use a pump to loop a descaler solution through it once a year.

In general, I have been satisfied with the unit. My only real complaint is that if you just want a low flow of hot water, the heater sometimes doesn't realize I am trying to draw hot water and won't turn on. They make all different sizes depending on your needs, though I am not sure if they offer a 120v unit.

Sorry, but this is an old topic and the depositry for the images is no longer active

I'm unable to see any of these photos in your post - any suggestions?  Thanks in advance!