My wife and I will start building a 14-15 ft diameter earth bag round wall cabin this June. it will be built on a 4 ft deep rubble trench insulated with earth bags brought up to grade. We will be using a mix for the bags being 25% clay 75% sand (only exception being the first course on rubble trench will have gravel in them) We are building in the Upper Peninsula where we get lots of rain and snow. We have a working span from June till mid-late October before the winter begins, so having the plans as complete as possible is crucial, also this will be our first earthen building so we are trying to keep it as simple as we can.
Question we have, is a bond beam necessary for such a small structure? Or would velro plates under the rafters suffice?
One last question, and this is really where were stuck at the moment, is roof ideas? Right now were contemplating a gable roof. Because of how small our structure has to be (because of building codes) we would link to incorporate a sleeping loft.
Right now were thinking from the inside out having our layers go like this, boards that we cut, one inch think white bead board, rafters with straw stuffed between, and another one inch thick white bead board on the other side of the rafter, we would put a layer of heavy gauge plastic over that, with sheet metal being the last layer?
We will do a post and beam structure on the outside of the house, so the roof would mostly be supported on that.
Let's see if I understand you correctly; octagonal? timber frame with an infill of earthbags. The bags need a bond beam, but this can be wood as has been done for millennia. The mass wall will perform well if the outer shell is well insulated. I would probably hang a stud wall off the timber frame and insulate that. Post a drawing and we can go from there.
posted 5 years ago
The house will have cylindrical walls like a silo, the roof will be square, gable style. The walls will not support the weight of the roof, the roof will be post and beam or round wood framing. I am thinking that the ceiling joists/rafter ties will be dual purpose and be our loft floor. So the roof rafters and ceiling joists are tied into a beam or top plate, If I have Velcro plates on the top of the wall laid out for tying in the ceiling joists to the wall would that keep the wall stable at he top? My wall will be 9-10 ft tall with 3.5 ft below grade
I'm not sure I understand what you mean by double duty celing/loft, but it sounds that what you propose sounds well within the structural limits, granted sound bagwork, decent velco-rafter connections, no excessive openings. a sketch would illuminate.
The unsolicited part: to me, it sounds like a lot of work and likely not the most spatially efficient to build a small round EB building under a post n beam gable if this is to be a small 4 season house and externally insulated. is that the intent of this building?
posted 5 years ago
That is the intent, I'm definitely open to ideas, the reason we chose EB is for the thermal mass we gain and if that is insulated we should be very comfortable in winter, were doing a metal roof so we are able to catch rainwater, if I did a circular metal roof there would be lots of cutting, more ridges and less loft space. I could increase the sq ft of my house and take out the loft to accommodate a circular roof, but to insulate and sheath the roof would require lots of cutting which probably means more mistakes, but maybe I'm mistakin I'm very new to this
Location: NORTH Great plains (spit wrong and hit Canada)
posted 5 years ago
If you aren't going to bury it, or have the walls support the roof, I see no reason you wouldn't make your structure square to make maximum use of the roofing material. Sure round is strong but square is simple - to roof, fill with furniture, insulate, etc.
You know you are rural- if you get a big black stain on the seat of your daily wear pants and no-one knows for a month...
I have 22feet diameter bag house and poured concrete on top and build 2nd floor with roof . I would do square if were you .Its pain to frame on round and lumber cost more as I didn't wanted post in middle .
Also plaster is easier to do on straight walls than round. I'm adding on both sides of my round house right now .No more round.Make good overhangs to keep rain off the walls!!
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