Sustainable Garage

Hello everybody! I just stumbled across permies through youtube and i am very happy to have discovered and to become part of this community!

I am designing a garage with a single bedroom apartment on top for myself and my girlfriend to build/ live in. In the design of this space i would like to use conventional & sustainable building concepts. The garage itself will be a 2 car garage with a small workshop area tucked at the back, also in this space, I am considering putting an alternative waist management systems such as Grey water treatment & a composting toilet reservoir. In the upstairs apartment portion I have decided to go with a small 1 bedroom apartment. I have considered many options for heating this space but have yet come to a conclusion on what sort of system to use. on Permies i have discovered the "Rocket Mass Heater" which is a very good idea but having the fuel intake open leaves me worried for if the fire were to spread. The combustion portion and the stack would be located in my living space and the thermal mass would cross through my bedroom behind my bed and act as my headboard. For water and waist management have taken a look at Levinlevinlevin's youtube channel (http://www.youtube.com/user/levinlevinlevin) and feel like this man has some great ideas for Composting toilets and Grey water treatment. For the building envelop itself i am leaning toward a staggered 2x4 stud wall on 2x6, 2x8 or 2x10 plates. As these are my exterior load bearing walls I do not know if this structure will suffice for supporting a second story and a roof. I have decided to stagger studs to create the least amount of thermal bridging as possible while using traditional framing methods. For the insulation I would like to replace the traditional fibreglass insulation with a straw bail style insulation( break straw bails open and insert dry straw into the erected cavity wall before applying my double top plate to seal it off. For my roof I have decided to go with Vaulted Ceilings Therefore for the roof assembly I will go for a traditional set-up. the material order i am considering from inside the building to out will be. Roof rafters, Sheathing, water proofing membrane, Rigid insulation, Strapping in the direction of roof slope & galvanized steel roofing.

If any of you guys have ideas that could help in the design process I would greatly appreciate your words of advice and links to pages that may help!

thanks
Jesse

Hi Jesse and welcome to the forum!

It sounds like you have some good ideas about what you want, which of course is important. I think you should take a close look at light clay-straw wall as an infill option for a somewhat conventionally framed structure. The way I've seen it done is with a 12 inch thick "larsen truss" wall frame. Basically a larsen truss is 2 parallel 2x4 studs held apart with small pieces of plywood or luan, so that they span 12 inches from outside to outside. These are set on a 2x12 plate at either 24 inches or 32 inches apart (depending on local codes). You then erect temporary forms inside and out and fill the cavaties with  straw that has been broken up and saturated with a "clay slip". You pack this wet, clayey straw into the cavity and then when you remove the forms and let it dry you are left with a dense, insulating, green structure that has a perfect synthesis of insulation and mass. No need for sheathing, the walls are then ready for earthen plaster after they dry out. There is a man by the name of Robert LaPorte who has been reviving this building method in the states and gives workshops all over the country. I would suggest you check out his website for more info: econest.com

Good luck!
Peter