giovanna. ash

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Recent posts by giovanna. ash

Why do you have to dig a trench, fill it with gravel, and then build the foundation up out of that? It seems to me that if you just dry stack the foundation on the ground, and build up the interior floor to be higher than the surrounding ground... that would keep water out. The uphill side of my build site is a forest, so there won't be much water flowing across the surface, and I could always put a french drain around the house if needed.

I'm only wondering because there are lots of roots and rocks in my soil, and digging down is going to be slow. And I can't see how having gravel directly bellow the foundation does much of anything that an adjacent french drain could do.
7 years ago
cob
Thekla- straw bale can be load bearing. But I don't think it is strong enough to hold up a living roof, or a second story. I had decided on straw bale for two reasons... one, it's faster to go up than cob (next summer a ton of people are moving into the house we are living in, so we want OUT as fast as possible). Two, I think insulation is a bit more important than thermal mass where I am... right now we are staying in the upstairs bedroom of my parent's home. It has two northwest windows and one southeast window. At night we would open them up (it gets down to about 70 at night in the summer) and it would stay comfortable in the room all day long (into the upper 90's). In the winter (which isn't too terrible, maybe average temp mid 40's and 30 at night?) I thought having all that insulation would work out well with a rocket stove heating the straw bale house easily, rather than solar gain heating it, which would overheat the place quickly in the summer no matter how man overhangs I had... and I know this is a problem here from being in other cob houses in the area. I could get really clever with the overhangs but that seems more difficult and more likely to fail. Am I wrong? I figured I could make the interior north wall have a thick cob layer to provide some thermal mass for the sun to hit and heat up in the winter (I plan on having some south facing windows) but since it's inside and on the north wall, the summer sun won't reach it easily.

It was actually suggested to us that we run a cob workshop (for labor and to help cover costs a bit). Sounds like a great idea.

I like the extended overhang/trellis idea. The only downside is not having that shade if something happens to the plant (I imagine living on the south facing, thermal mass wall of the house can be a bit hot for some plants). I have planted apricot and cherry trees on the south side of my build site.

Sam- I also like everything I read about living roofs.

If I'm going to build the roof before the walls... I think that will defeat the purpose of building load bearing straw bale walls in order to save money on timber? Because something has to support the roof. I do have some nice cedar on my property I can use, like I did when I built my tool shed:

http://www.flickr.com/photos/genissimo/5711837448/in/set-72157626858101281


7 years ago
cob
What is a natural solution for insulating a roof, other than soil?
7 years ago
cob
Thanks for the ideas, Dale.

Sam wrote:
You could always use wooden shingles as your roofing material (with a waterproof layer and insulation underneath).



But wouldn't that waterproof layer also be something I could use for a living roof?
7 years ago
cob
Good advice. I will concentrate on site prep and the roof.

Is pond liner the only way to do a living roof?
7 years ago
cob
I'm in the planning stages for a cob/straw bale house I'm going to build next year. I thought I would post some thoughts here to get some input, since I love reading this forum and I have gotten a lot of ideas from you all!!

Some context:

I live in central NC, and there's plenty of clay around here. The climate is temperate (leaning towards the warmer side). It's also very humid. My parents have six acres they were dong nothing with, so my husband and I moved in with them and started a two acre permaculture forest garden (well, it will be two acres when it is finished). Now we want the eco house to go with it! (We're pretty tired of living with my parents, anyways) The site is at the top of a gentle slope that is a big open, grassy field (the field we are filling in with the forest garden)... I'm really scared of digging down and hitting bedrock, since the property is sort of half floodplain and half rocky outcrop.

I own the $50 and Up Underground House Book and the Cob Builder's Handbook... as well as this old book I found at a used bookstore called Passive Solar Energy written something like 30 years ago. That and the two cob houses I have been in are my source of info of how to build something like this. I thought I was going to have $3,000 to spend on the house... but I just had a baby and long story short... my savings have been depleted more than I thought they would be (thank you insurance company). So now I have to do this house on as little as possible.

I have a friend who recently finished building her own house this year. Here is a link to a big set of photos of the build start to finish (or I guess there is still some plastering left to do, so there may not be "finished" photos yet!):

http://www.flickr.com/photos/danielleackley/sets/72157623078007101/

One of the guys who helped her build this place has taken workshops with Ianto Evans in Oregon... boy am I glad he flew all the way out there so I don't have to!! He is currently building a cob/conventional home hybrid for his parents to live in. He is blogging about it here:

http://cobandon.blogspot.com/

I'm thinking I want to start with just one room.. with a loft space above. I think the loft space will open it up and give the downstairs a big, open feeling even though it's a small space. I also know that roof/foundation are the biggest expenses, and building up takes advantage of that. I'm thinking upstairs can be a nice cozy sleeping loft in the winter, when warm air rises up. But in the summer, I was planing on trying to create a solar chimney effect... is there anything wrong with this plan? Or is this just "strategically placed vents" and not a solar chimney?? See attached photo. Notice my roof slopes downhill... thank you Mike Oehler!

For the roof, I understand pond liner is a huge expense, so I don't want to do a living roof... but that is by far the most attractive option. I don't mind just a tin roof, but will I have to replace it often? Can I put a layer of dirt under the tin roof (for insulation)? Or a layer of straw? Is that a stupid amount of flammability?? I would rather have a living roof for the strength and insulation, if there is an affordable way to do it. How does evaporative cooling work with pond liner? And if it does, how does it not drain the house of heat in the winter? I do have plenty of woods on my land, so I can harvest some trees for the roof.

I want the bale walls to be load bearing, because I don't want the expense of timber/nails/labor (I am no good at woodworking so would have to hire someone). Does this mean I have to have straight walls?

I want to build a rocket stove... is there an advantage to putting the heated cob bench on the south vs. north walls? Can I run the exhaust pipe through a straw bale wall or does it have to be a cob wall? I'm thinking most of my walls will be straw bale since it gets pretty hot here and I don't want the thermal mass of the cob overheating the house in the summer. Or is cob supposed to cool in the summer as well? My friend's cob house is straw bale only on the north wall, and it gets a bit toasty in there this time of year. There is not sufficient overhang though, so I'm not sure what it causing it exactly.

Also, if I have some leftover dirt, I was wanting to make a cob wall sun trap. My understanding is that it's just a cob wall in a cupped shape, facing south. And then you plant stuff in the curve on the south side. Right?

-Giovanna

7 years ago
cob
http://weblife.org/cob/index.html

This is a link to the Cob Builder's Handbook. I am drawing up plans right now for a similar house (just a bedroom and bathroom)... but it is likely only my north wall will be straw bale. My south wall will be cob so it can absorb the heat from the sun and slowly release it at night during the winter. Any reason you are doing all the walls straw bale and not combining with any other methods?
7 years ago

paul wheaton wrote:
For the tour of cobville ....   I had a lot of people asking me about the sun trap temps.  Ianto does not care for the internet, but Ernie, who hangs out in this forum a lot, has huge experience in cobville.  So I asked him.  Ernie says that it is about 30 degrees warmer in the sun trap!



I can't find any info on the internet about sun traps. Is that included in the cob building book you recommended?
8 years ago
cob