Thanks for your response and encouragement!

I spent a great deal of time investigating the winter sun and summer sun angles and came to a disappointing conclusion. My latitude there is 19.343N (about two hours by car due east of Mexico City) which puts the June 21 noonday sun 4+ degrees north of straight overhead and the December 21 sun 47 degrees up from the horizon. Given the amount of rainfall that comes out of the south mostly in the summer, the protective overhang needed to keep the foundation and walls dry impinged on the angle of winter sun that I could use to heat the floors and walls.

I am thinking that the massive adobe walls (16-24 in thick) inside the house will be able to absorb significant amounts of heat generated during the day from normal human activities, sun hitting the roof, etc., and release it during the night back into the house to maintain a reasonable daily temperature swing. I also intend to use a quilted material with a reflective aluminized plastic film sandwiched in between (personal adaptation of a product sold at windowquilt.com) to pull down over the windows at night to minimize heat loss through the glass. The altitude is 7700 ft so the summer days are quite cool, around 70F, but the winter nights are relatively mild, dipping about 15 nights a year down below freezing at night, comparable to southern California where we are now. My goal is to be able to have a well insulated house that needs no significant additional heating in the winter. The vast majority of people there use no heat or air conditioning at all in their homes, but I don’t know that I want to be that brave.

We are planning a house that has a perimeter of 250 feet and so a single perimeter pour would be a challenge. Do you think that would be doable if we had the slip forms in place for the pour and poured one batch of papercrete into wheel barrows and began placing it while the rest of the crew made another batch of papercrete? That seems like a tremendous amount of wood for 250 feet of slip forms. How long would it take after an initial pour before the papercrete would not bond completely in a given row due to too much time between batches? Could you slope the end of a batch out over 4 or 5 feet and then continue on horizontally with a new batch from there?

I had considered installing solar powered radiant floor heating, but the least amount that it seems that I can spend is about $3000. I can buy 20 or 30 years of firewood for that amount. I’ve also looked into the rocket stove mass heater, which I like very much. I’m trying to build the house finished for $35k-$40K.

Your efforts are inspiring! I figure if you can do it, I can, too! Onward and upward!

Tim

I’ve completed 2 small building to the finish stage using the slip form method. On the first building I framed in the doors and built the walls around them. I am noticing now that a crack is forming at the corner of the French door opening – a 5 foot opening. I have a good lintel over it but apparently it didn’t make a difference. I am not worried about this crack. I will let the building continue to settle, reframe the door and finish it with plaster later.

On the second little building I was careful to pour all the way around the building with just one 4 foot space left open for access. I poured 2 courses completely around the building before starting the door opening then just left 4 feet open. It will be a 6 foot door. I put a good lintel over this one too. The difference is that I waited until the building was completely cured before coming in and cutting out the door and window openings with a chain saw. This second building looks a lot better than the first one I did, but when they are finished and plastered the difference won’t be apparent.

I think your plan has merit. If you want to store some heat for night time be sure your adobe walls can soak up the sun all day. In my first house (which I no longer have) I took an 8 foot 2 x 4 and stood where the doors and windows would go. I watched the shadow of the 2×4 to see how far the sun would penetrate into the room and put the rear wall there. It was 14 feet on the shortest day of the year. Are you sure you will need a lot of sun and heat in Mexico? I am excited for you and hope you will keep in touch and let me know how you’re doing. If you have any more questions don;t hesitate to ask.

Did you get any cracking or shrinkage in your building? I am seriously considering building the exterior walls of my house out of papercrete and the interior walls of adobe for massive heat storage and I am wondering if I should do the monolithic papercrete pour or build the walls of 12x24x6 bricks and use papercrete mortar. Do you have an opinion at this point?

Thanks for your time!

Tim
in Riverside, CA, planning to build in southern Mexico later on this year