Winter is finally over for us in MN, and I am about to start the excavation process for a cabin I've been planning for some time now.
Current plan is to dig a full basement to get around the frost depth we have in MN. Code specifies 5ft minimum depth below grade, so that's how far down this thing will go.
Foundation will be full perimeter CMU with filled cores and a 24" x 9" footing profile. Waterproofing membrane to be installed around the lower 78" of the foundation before backfilling.
I have some sketchup designs here if anyone wants to take a stab at issues with it. (first floor doors/windows aren't in the model yet)
First floor sitting on 11 7/8" I-joists to span 14' 8" across CMU walls. 24" O.C. 3/4" OSB sub-flooring
Long-axis walls are balloon framed 2x6, 24" O.C. with 12' tall studs and a floor starting at 8' height. supported additionally by 8" ledger and fire blocking at 8'.
Short-axis first story walls are standard 8" height with double top plate. also 2x6 24" O.C.
1/2 story and roof are where things are a little more interesting... Roof has structural ridge, 3-ply of 26' 1.75x16" LVL. Big mother of a built-up beam. Allows for a clear 23' open span in the room.
Ground snow load here is 60psf, roof pitch is 12/12. Rafters are 2x8 24" OC. Will be secured with metal hangers and hurricane straps. I have no idea if I can get away with the slider windows right down the center of the beam's path to the foundation. Another option is two smaller single hung windows side by side of the supporting column as it goes down to the floor. Less header headache. I am still worried about the floor being the rafter tie 3 feet below the point at which the roof exerts some thrust on the wall... With the ridge holding half the weight, each stud is still going to see ~90lbs of thrust outward. Seems manageable for each 2x6 stud, but I haven't calculated beyond this...
The floor is to be 2x12 or I-joists again, except in the center portion where half the floor is open to let in light from (potentially) skylights and let heat up from a wood stove. I think this floored portion in the center may need some better engineering to deal with wall thrusts. Not sure on this.
Collar ties are just to hang electrical and what have you. I like having the void in between each pair as it seems ideal to tuck away wires and such!
Soil is sandy clay, but with the total weight of this building on the total foundation footprint I've prescribed, the soil will be fine. 156 sqft of footprint and total snow-loaded house weight of 80,000lbs
Here's some sketchup stills of the frame I'm imagining... (sans basement) Open to any suggestions on this. Really would like to have plans in a "do in once, do it right" state by mid-summer or so.
Thanks for stopping by!