I'm not familiar with anything like that (but there may be something). You could always just pour a conventional concrete wall with wood forming, strip it, and attach your insulation to the outside, leaving the inside concrete exposed.

I'm in the very early planning stages and haven't worked out the economics of a formed and stripped wall compared to a reinforced concrete block wall filled with concrete. Both are pretty labor intensive. And, I'd prefer that the foam be mechanically attached to the concrete as opposed to just using adhesive....

Certainteed makes "Thermeze" EPS inserts for a regular poured-wall forms: http://www.certainteed.com/products/foundations/foundation-insulation/311483
Or Western Forms' similar approach, called E-Maxx http://www.westernforms.com/Applications/OtherApplications/InsulatedWallSystems/EMAXX/tabid/163/language/en-US/Default.aspx
Dow's prefab T-Mass puts the foam in the middle of a concrete sandwich: http://www.thermomass.com/
There are a goodly number of companies that incorporate exterior foam in stay-in-place forming systems. Residential versions tend to come and go, usually in florida where concrete homes are standard practice. Here is a commercial building product http://www.octaform.com/index.php?page=insulation
A DIY approach would use screws to attach metal rib lath and foam boards to steel studs, site-building a form that would stay in place after the pour.
6" of foam will take more engineering and more money than these basic approaches, and may be overkill depending on where you are.
Here is a cast in place primer that has lots of links http://www.wbdg.org/design/env_wall_castinplace_concrete.php
Happy hunting.

If you want to use the thermal mass of the concrete wall to hold and transmit the heat of the sun then I don't think you want to use foam over the concrete as the foam will not allow nearly as much heat to be absorbed.  Along these lines have you looked into using a trombe wall?

Hi All,

Rio,
I'm not a big fan of trombe walls simply because they limit views of the outside and the space between wall and glass is hard to clean. But, if the view to the south is less than attractive, it gets my vote. And, It certainly is nice to have in the design repertoire.

Toddm,
Thanks for those links. It's been 5+yrs since I've built and I don't think I recall any of these products. I just wish the insulation was thicker. I want a R25 to R30 rating on exterior walls... I suppose I can always add more outside of that.

David

Hi David,

I'm game with a few questions/thoughts. Why not just build an regular house with Insulated Concrete Forms (ICFs), where the insulation on the inside and outside? I simply feel that from a cost/asthetic stand point, you will get the most bang for your dollar. ICFs will allow you to have the R25 to R30 rating you wan and you can finish the inside with sheetrock, plaster, etc.

With the interior walls with concrete you are either going to have use conduit for electric or find a clever way to put the lines inside the concrete wall, which will add to construction costs. Also, with the concrete wall on the inside painting will be a challenge to a certain degree as well.

If this is truly what you want, then I absolutely say "go for it", but there are other options available go get a passive solar house. ICFs in my opinionwould be a more practical way to go about it. Lastly, if you are hell bent on having the interior walls finished with concrete, then I believe it could make finding a future buyer (upon selling it) could be a bit more difficult. If you like more information on ICFs just go to that part of the forum and ask questions. You will get some strong answers.

Good luck.

renangle

Talk to the guys at TF ICFs. They have a way that you can use their system that way.

Ideally you would use a product such as Mag board for the inside form and you would not have to remove it.

Hi all again,
renangle,
Every time somebody wishes me good luck I think of the quote: "Luck favors a prepared mind"
I built a passive solar ICF house and have lived in it 5+ years. I think they are great. But I know that from a thermal mass / heat storage perspective the insulation will be functionally better all on the outside.
No argument from me that it would be a hassle both during construction and to some degree while living in it; ("Honey, I want to hang this picture here. Could you get out the hammer drill.")
At this point I'm thinking I will just plaster the exposed concrete to look like the other walls of the house. Then I will have to be careful about what form release agent I use... Or if I could somehow incorporate a product like mag board into the interior form as jmagill suggests.

jmagill
thanks for those suggestions. TF ICFs use a interesting approach. I like it. And thanks for the Mag board suggestion as well. It's interesting stuff.

Again, thanks to all
David H.

"If I have seen farther than others it is because I have stood on the shoulders of giants" (Isaac Newton)

Dave;

It might be of interest to you to take a look at the following threads here on greenbuildingtalk..."Crawl space or not"...."Internal wall surface temperatures" and "lop-sided Block"...

Some stand on the shoulders of giants...but have their eyes closed....It seems that you have your eyes open LOL

David,

Okay, let's for the sake of arguement, agree that from a thermal mass / heat storage perspective the insulation will be functionally better all on the outside. How much better do you really believe that it will perform? Depending on how much it will cost you to put up the system you would like, place mag board on it (or plaster), getting a hammer drill to put up a picture (for you and a possible new owner in the future), wiring difficulties, etc...do you believe that you will be money ahead? I would have to think that the return on the investment will take a very long time.

Just to cover your bases, why not get in touch with Energywise Structures or some other outfit that can provide you with an idea of the energy performance of the two systems before you break ground so you can make the best decision possible?



T

If return on investment was the only measure of performance for his project then he would go with SIPS instead of a concrete or ICF system. You would get far more insulation for less money right up front. He is building a passive solar home and to get the most comfortable home possible you need the mass not insulated so it works to it's optimum.

The easiest way is to build a CMU wall, pour it full of concrete, and then put board foam on the outside. This would let you use conventional technology that contractors are familiar with. That might not mean much to you guys, but in the boondocks, it really helps.

Hi all,
donnerwetter
Thanks for the suggestions. Much appreciated. I'll dig into those threads a tad later.

renangle,
I feel it will perform much better with all the insulation on the outside.
In a passive solar house any delay (because of insulation around a absorptive material) will cause the structure to heat up to uncomfortable levels before the heat energy can be absorbed.
I have exposed stained concrete floors in my present house that do most of the absorbing/storing/radiating.
The concrete mass in a ICF wall is in limbo. It's halfway from the outside extreme temperatures and halfway from the moderated temperatures inside. In attempt to find equilibrium heat flow will tend to be to/from the side with the most extreme temperature(outside). So the mass in ICF walls is only valuable in temperate climates - and probably in non-temperate climates even a hindrance to some degree.

I want as many parts of my house working for me as I can get. So, if I'm going to spend money on concrete structure it should give me heat storage mass too. I don't want it in limbo.

aardvarcus
I grew up in the boondocks. Using CMU walls and board foam is one way under my consideration. There is a lot to be said for simple, conventional technology. I'm considering dry stacking, surface bonding but want to reinforce the walls with some horizontal re-bar which for most CMUs is a challenge. I haven't seen many notched CMUs, so, that would have to be done on site with some expected breakage... I could use a sacrificial table saw and dado blade setup.

...Passive solar is simple too but it's not mainstream. It's frustrating on some levels. But, ultimately the only life I have complete control over is my own.

David

BTW My ICF house is in NW Arkansas, is 3500sf, electric bill is level-ized at 87$/month, highest gas bill is always in January and has been less than 150$ every year (not a lot of sun here in Jan.). It qualifies as a NAHB bronze home.

David,

I understand what you are trying to achieve, but I think you are forgetting that any concrete wall must have a frost wall built on the inside. Even if you pour a traditional concrete foundation and only insulate the outside with EPS, you still need to have insulation on the inside of the wall. If you neglect to insulate the inside you will have frost issues. Furthermore if you plan to run any exterior wall electrical you are hooped. Is your intention to leave the walls on the inside as bare concrete, if so this will probably raise some Red Flags with you local building code.

I would encourage you to re-consider your options. There are many products out there that will give you the energy efficiency you are looking for. You may also want to consider the amount of energy required to heat up your concrete thermal mass, is it really helping lower your energy consumption or is it a large consumption of energy in itself?

Just my thoughts.

Proper Solar design requires the mass to be comfortable and temper the temp. swings. There are foundation systems available that break the connection between the frost wall and the interior concrete. Have a look at the Passive Haus foundations (no frost wall at all). You only bring the temp of the concrete up to temp once and then it does not need to be brought up again as the sun keeps it stable. Building code allows concrete in the form of fireplaces and rock walls, why would this be any different?

Electrical can be done with conduit before the concrete pour. Just takes a bit of preplanning.

Like I said I understand the concept of a Solar Passive house. What I don't understand is why you would want to live in a house with bare concrete interior walls. As the outside temperature changes (seasonal winter to summer) so will the concrete mass. The energy required to keep the concrete warm in the winter will be substantial and will require more than just the sun alone. Depending on location, this energy load will be greater than others. Is this cost worth the hassle?

First of all, you can cover the concrete with anything you want from plaster to brick. You could stain it like my concrete floor is stained. It could be amazing, the possibilities are endless.

Second, you don't understand passive solar if you don't get concrete walls and steady state temp. The concrete is insulated on the outside , there are no massive temp changes and no massive need to keep inputting energy. The sun does the majority of the work and it costs nothing.

I believe this is a never ending argument. You are entitled to your opinion, and I can respect that. You can build whatever you want. I will build my structures with high insulation values and minimal concrete.

To each their own.