Interior walls

My husband and I have decided to make a cob home and have been doing a lot of research before breaking ground to make sure we have a good understanding of everything that either does or will need to be done to make this practical. However I have been having some trouble finding solid answers to a few of my questions.

1.) Can I build my exterior walls and roof then begin the process of building interior walls? Or do they all need built at the same time? I know that I will need to allow my house to fully dry out before plaster or moving in but I wasn't sure if I could get a roof up and then begin the inside or if I need to do it all at once.

2.) Cooling? I know that window placement is key. No skylights or windows higher than the winter sun or on the west end if I can avoid it. I also know that the cob will cool at night to help regulate its temperature. However, where I live the summer nights can sometimes only cool down to 70°F witch can prevent the cob from cooling off enough at night. What can I do to help insure I don't build a giant summer time oven to live in?

3.) We were planning on doing a form of hybrid to help with insulation since cob has about a R3 value for every 12" of wall thickness. Should a fireplace alone be enough to help heat the home? We can also have some pretty cold winters in our area. Not always but often enough I want to make sure I'm prepared.  On that same note does anyone suggest one type of hybrid over another? I've seen straw in walls as well as rebarb holding basically two giant slabs of cob together with conventional insulation in between.

4.) We were thinking of doing some stick frames where the water pipes come up into their respective places to make repairs easier in the event of a pipe bust. What have others done to make the possibility of this situation easier to handle?

I appreciate all of the help I can get and if anyone is currently building in the Ozarks and would like some help for a day or two that way I can learn more I would be very grateful.

Hello Rebecca, I am also thinking about my yet to be build rammed earth / clay+sand+gravel house.

4. Pipes: I would add a small extension building (maybe 1 by 1 meter) where the pipes come up from the outside and then feed them through a somewhat larger pipe that acts as a conduit so you can access and replace the pipes when needed. It can also double as a shed/firewood storage/workshop.

1. I would probably want to secure the interior walls to the exterior walls to avoid them falling over. But that can be done after exterior walls are build. For example a small slit (3cm deep) could be cut into the exterior wall, or holes could be drilled and dowels be used.
If the statics of the exterior wall require the interior walls for stability, it is a different question that I can't answer.

2. If painting the outside white (lime or titanium dioxide) is not sufficient and you have already blocked direct sunlight during the day, active cooling is always an option (more on that below).

3. Yes! Except I don't plan on building another massive wall on the outside of the insulation, but just cover it with wooden cladding. That also allows accessing the insulation at a later time.

Your said that sometimes the night temperatures don't drop enough for cooling, so you need some other way to get rid of the heat.
That can be a underground geothermal storage (a lot of pipes buried in the soil) requiring only a bit of electricity to run the pumps, and/or a heat pump that can run both ways providing heating in winter and cooling in summer. As the name implies it moves heat, so you still need somewhere to put it. That somewhere can be the outside air (less efficient) or the geothermal storage. The efficiency depends on the temperature difference of the temperature you want inside and the outside air / thermal storage.

Sebastian,
Thank you so much for the advice! We will definitely look into the possibility of doing some of this when making our plans. I know that Cobb homes are possible in our area because there are two other in a neighboring town but I haven't had a chance to speak with those people so it's nice that someone who is familiar with this building style can help us with the nittany gritty questions.

There is a post here about cooling homes in hot climates. Middle eastern wind towers etc, I have used them a lot.
Where are you building?

Rebecca Priester wrote:
2.) Cooling? I know that window placement is key. No skylights or windows higher than the winter sun or on the west end if I can avoid it. I also know that the cob will cool at night to help regulate its temperature. However, where I live the summer nights can sometimes only cool down to 70°F witch can prevent the cob from cooling off enough at night. What can I do to help insure I don't build a giant summer time oven to live in?

4.) We were thinking of doing some stick frames where the water pipes come up into their respective places to make repairs easier in the event of a pipe bust. What have others done to make the possibility of this situation easier to handle?

Some thoughts.  We are building a house, too.  I live in a very hot climate, where there are many nights not getting below 70 in the heat of summer, unfortunately.  And it also gets a bit below freezing in the winter.  We are currently living in a cement block house, which probably has similar R-value to cob the way it's built.  It is an oven in the summer, but it didn't have to be - we didn't design it though. We are building a different house from scratch, and taking many steps to stabilize the interior temperatures.

Besides window placement, the other big keys are:

1. Overhangs and shading exterior walls
2. Thick roof insulation - an incredible amount of heat penetration comes through the roof, as well as heat loss
3. Exterior shading of windows, overhangs or other techniques - besides south windows, it's particularly crucial to manage sun if you have to have some east and west facing windows for whatever reasons (such as egress, air flow, view, etc.)

Our building (exterior walls, roof, porches) for our new place is up and we are able to see how these calculations worked.  The calculators we used worked quite well so far.

For overhangs and window placement I used this guy's awesome free programs/calculators:  Sustainable by Design free passive solar design tools

I found the Sun Angle, Overhang, and Light penetration tools very helpful.  We also used an inexpensive home design program that had a sunlight feature for checking the sun coming in windows year round.

As far as thick roof/ceiling insulation and exterior window and wall shading... We've lived 6 summers in the desert SW without air conditioning or swamp cooling, seeing temps in the 110-119F range many times.  One house was an old stick built we had to remodel.  We were able to experience firsthand the benefits of exterior window shading and adding about a 1 foot of ceiling insulation.

We did temperature measurements before and after, and could really "feel" the proof of how effective these techniques are to keep a house from cooler in summer.  For exterior wall and window shading, we used sun sails in the summer and took them down for winter.  That dropped the shaded wall interior temps average 7 degrees.  But the insulation we had added above the ceiling did even more for comfort.  We wished we had done that first!  

If you can have trees do the shading of the exterior walls, that's even nicer, but if you can't then sun sails are the cheapest and fastest.  Next are these pull down exterior window shades, Coolio is one brand.  Louvered or trellis shade walls (for east and west sides) look nicer and last longer.  Louvered or solid porch roofs/overhangs are the best value overall, though, as they may last the longest with minimal maintenance. Solid overhangs protect your walls and windows from rainfall as well.

As for the part about water pipes, we also had to replace and remodel two bathrooms and part of a kitchen.  The house had a cement slab, so that had to be torn open and fixed.  The plumbing went through both the walls and the slab.  It would have been so much nicer had the plumbing only been stubbed through the slab to the point of use wherever possible.  Then we wouldn't have had to fix BOTH the slab plumbing and rotted walls. When building, you have the option to think ahead about which you'd rather be stuck fixing in case of a leak.

We replaced the incoming plumbing with exposed copper piping, with permits.  It wasn't an issue and that was California.  It looked really nice and was a selling point. Plus one can see any leaks quickly that way rather than wait until they mess up your wall.

In the house we are currently building we're also doing exposed copper plumbing for the incoming lines. It takes some creativity, but once we figured out how we were able to make it look really nice. We used Sharkbite type fittings and copper bell anchors for mounting.  You can still use regular faucet fittings.  You can buy premade exterior mount shower fixtures designed for outdoor showers, or you can put together your own setup for less money if you want.

Two more things regarding cooling... lots of opening windows and really nicely fitted screen doors help immensely.  I finally came to understand the value of so called "security" screen doors.  They are great for airflow.

Hope that helps and good luck!

John,
We are building in Southwest Missouri. And I feel as though we need to be prepared for most things. Sometimes our summers can get in the upper 90s, and sometimes our winters can have a two-week ice storm. We can also experience heavy rain for a month of Sundays as well as a drought bad enough everything turns into a crisp. We also live in the middle of tornado country. This is why we've chosen a circular design for the house. Our location is in the middle of the woods so we have shade working to our advantage. This is our first time with natural houses and non-conventional building, so any recommended books or articles are greatly appreciated.

If your exterior walls will be roundish, they will have plenty of strength to stand without interior walls. In tornado country, I would really want a wood post frame to support the roof and not incidentally to anchor it down in case of high winds. This will let you build the roof before any walls, and protect the walls from rain while building them.