Do most people not know about Thermomass insulated concrete sandwich wall systems. I looked into ICFs and found them to be more expensive to install (unless you DIY it and this can be risky). I selected T-mass for my project as well becuase it lent it self to using the concrete as both the interior and exterior finish.

Why is no one talking about this as an option and or alternative to ICF's.
Check out this cool image I found of the exterior of home built in Australia using T-mass for the entire home.

I am also intrigued with Tmass but inquiries have found its more expensive especially for whole house application. I am wanting to do a modern minimalist passive solar home. So the concrete on the outside/inside for the thermal mass is more appealing than an ICF w/ the concrete insulated. However, the contractor has to leave the forms up longer in order for trades to run electrical or any plumbing needed. I hope more pre cast concrete companies who are mostly commercial, get into residential and competition will bring prices down.

Here is a home in Mpls using Tmass http://shelterarchitecture.blogspot.com/

Also the NAHB model home from the International Builders Show utilized Tmass. They did a really cool blue/green acid stain on it.

I believe Western Forms has a similar system to allow you to locate the foam insulation anywhere between the forms.

Hammond,

Are you going with a precast or poured in place system. How much are you paying for just the thermomass shell (material and labor)?

I've never heard of anyone who says that ICF's are less expensive unless you're able to do all the labor yourself. Try plumber Concrete out of Ellsworth Wisconsin they're pretty price competitive for T-mass. Forecast does precast wall systems and did the shelter house you showed in the link which may be a bit more expensive than poured in place like I'm doing but provides a beautiful finish on the walls as they are created on a flat table and can be more easily vibrated. All the electrical is run through chases that are built into the walls and shouldn't require the forms to be up any longer than on a traditional concrete pour. one thing you need to consider with ICF's is that the exterior of a T-mass system can be used (in your case and in mine) for the final finish however ICF's require some sort of exterior finish to complete the building envelope.

My home will feature just the north wall and foundation in T-mass the remaining exterior walls will be SIPs.

So you are saying that erecting the metal forms, setting in the foam and the connectors, pouring the concrete and taking the forms off when concrete sets is less expensive than erecting the ICFs and pouring the concrete?

and the electrical boxes need to be preinstalled prior to the pour, and how do you attach sheetrock?   Many customers still prefer sheetrock walls, and the exterior finish (aside from the poured concrete) ? I can see alot of tapcon screws and powder actuated fasteners.  Still, for certain applications (like they state Home Depot, Correctional Facilities) I can see how this makes sense.   I think it would be difficult to apply this to the residential side.

Hammond91,

 

I looked into T-mass system quite closely before going with ICF. My conclussion was the themal mass benifit did not justify the cost.  The cost I was quoted for the T-mass material, 6" of foam and the required connectors, was $5.85 per sq-ft. Add the additional costs of ele in conduit and time the formers will have to wait as your crew or theirs works it in. I will bet it will take twice as long to form a wall with T-mass compared to traditional Removable forms. That's going to cost you, big time. I was clearly shown this by our local wall forming guys! Unless you like the look of formed concrete, some finish will be required. Take a look at formed walls after the forms have been pulled. Lots of form joints and defects from the last 50 pours.

Benifits or lack of..

Thermal mass benifit is based on cycle temp swings. Unless you have enviromental conditions where daily temps go above and below inside temp in one or two day cycles, you will not see much effect. Thermal mass is most benificial in high plains of the south west. It's not uncommon to see nights in the 30's and day time highs in the 90's. Also, if you are primarily using this building method as a basement, less benits will be seen. An ICF with concrete floors via a Hambro or Speed floor system will give you all the Thermal mass you can effectivly use. Adding extra foam to the outside of a ICF will have far better return in a some what stable temp climate. In high temp swing areas, less insulation has greater benifits. An ideal system would have a variable insulation system so heat could be moved at will. I have played with a concept of using vacuum panels. vacuum has a R-value of 250/in. During extream temp differentals, max vacuum. during big temp swings, no vacuum/insulation.

Patrick T.

Hammond91,

 

I looked into T-mass system quite closely before going with ICF. My conclussion was the themal mass benifit did not justify the cost.  The cost I was quoted for the T-mass material, 6" of foam and the required connectors, was $5.85 per sq-ft. Add the additional costs of ele in conduit and time the formers will have to wait as your crew or theirs works it in. I will bet it will take twice as long to form a wall with T-mass compared to traditional Removable forms. That's going to cost you, big time. I was clearly shown this by our local wall forming guys! Unless you like the look of formed concrete, some finish will be required. Take a look at formed walls after the forms have been pulled. Lots of form joints and defects from the last 50 pours.

Benifits or lack of..

Thermal mass benifit is based on cycle temp swings. Unless you have enviromental conditions where daily temps go above and below inside temp in one or two day cycles, you will not see much effect. Thermal mass is most benificial in high plains of the south west. It's not uncommon to see nights in the 30's and day time highs in the 90's. Also, if you are primarily using this building method as a basement, less benits will be seen. An ICF with concrete floors via a Hambro or Speed floor system will give you all the Thermal mass you can effectivly use. Adding extra foam to the outside of a ICF will have far better return in a some what stable temp climate. In high temp swing areas, less insulation has greater benifits. An ideal system would have a variable insulation system so heat could be moved at will. I have played with a concept of using vacuum panels. vacuum has a R-value of 250/in. During extream temp differentals, max vacuum. during big temp swings, no vacuum/insulation.

Patrick T.

Hammond. Where are you building? I am building in MN. Our weather can be in the 80s and 90s in summer and cool off to maybe 65-70 at night and winters, bloody cold 24/7. I am guessing that insulation is king rather than flywheel effect of mass except that I will be doing a passive solar(lots of glass) on my south facing lot on a lake. Polished concrete floors should be enough but I do like finished concrete walls as well. I am planning a modern minimalist loft like home w/ flat roof (similar style to the 5ive Home) and trying to figure out the best and cheapest way to accomplish the plan. Anyone w/ ideas please post away.

Patrick, I've never heard of vacuum panels. Have any info to post?

Hammond, Oops. Just noticed you are doing the Star/Trib blog I read about on LiveModern.  Awesome project!  I'll be following your progress closely.  Good luck with it!    My property is on Priest's Bay on Minnetonka.

slenzen,

Vacuum as insulation has been used for a long time in Thermus bottles. Vacuum is hard to maintain for long periods and structurally tough in any thing out side a sphear. My panel concept is to accept some leakage and to have a vacuum pump to maintain vacuum when needed. The concept is based on variable insulation. This is the opposite of adding heat when it's cold/hot. Instead, you would increase insulation via a vacuum. but like wise, there are times of the year when you would benifit by having no insulation. The panels would need to be made in such away that they do not conduct heat. fiberglass sheets seperated by many fiber glass rods would be one concept. The force is quite great.

Just a concept but not likely to get a good look until price of energy goes up further.

Patrick T.

Patrick,

I'm interested in why you looked at doing T-mass with 6" of foam. 3" of foam will equal an R-19 and that does not take into consideration the thermal gain which I was quoted by T-mass equaling R-33 for an above grade wall?

I think that your reference to the thermal benefits of daily temp changes not mattering much may be a bit off. The swing from High to low temps on a summer day in Minn. and or Wis. can range from 40-90 in a day or as in this coming week where the highs are expected to go from 70-90 overnight.

For me I love the look of worm holes and panel seams that you get with exposed concrete, as you can see in the picture I attached which used some sort of form liner to create the look of old wood forms. This may not be for everyone but it did influence my choice to use T-mass. Prior to the T-mass system doing a modern exposed concrete look was for the most part impractical in our climate.

The vacuum wall system I've heard of people in Europe talking about but my understanding that it works in theory and not in practical application can you tell me more who you see this working.

Thanks for all the great info. and exchange of ideas.

Jason


I

Hammond, how did you arrive at decision to do Tmass for your north wall and sips for the rest?

Jason,

I looked at 6" of foam because I wanted R-30 for static temp conditions. The Majic of the R-equilalence game, is in the temp cycle swings. So if you have -20 some Febuary night with day time highs in the single digits, the thermal equivalence falls apart. You will have 3" of DOW foam @ R 5 per inch, R-15. I'm sure some days of the year you will have a nice swing above and below inside temp. This concept is clearly explained at the Oak ridge national Labs. They have selected 11 regions arond the nation and given a rating for the Thermal mass effect. They also rate wall systems that are good in high thermal mass effect conditions; 1) Foam on the outside/concrete on the inside faired best, 2) Concrete sandwitch/Themal mass was second, ICF was third and other methods fell below. How did T-mass justify the R-33? national ave? based on your location? Find any local new stations web site. Scroll to the weather area. You can find the daily high/low for last last year and aves for decades. Now count the days where the temps swing 20 deg above and below 70 deg. If it is less than half the days per year, you may want to consider additional insulation and Geo-thermal.

As I have stated, some areas have very little and other very high ratings depending on your climate. This is no different than Solar. Here in Indiana, when the sun shines it's hot outside, when it's cloudy it's typacally cold. IN has a bad solar rating compared to say Colorado. Sun shines 300 days a year. You have to do the research on your climate. I did mine and it made more sence to invest in insulation. I will have thermal mass, about 475 cubic yards of it! But I will also have 7.25" of foam on my walls and close to 16" under my flat concrete roof.

I too like to look and feel of concrete buildings. When I was traveling to Mexico, Italy, Vienna, Prague, Thailand and China, thay all were constructed of some masonary product.

Vacuum insulated homes is a far off concept.

When will you start your project?

Patrick T.

Slenzen,

The idea to use T-mass for the North wall was an idea my architect had. We had a need to have some sort retaining wall and the T-mass was able to both work as structural element of the home and a barrier to manage the slope at the back of the lot. We were originally looking at stick framing but I was very interested in both geothermal and SIPs as options. The geothermal seems unlikely to happen as the quotes I have received have been so high that the rate of return is about 30 yrs. I've spoken with two energy specialist one private consultant and one from the State who both advised my strongly to invest in the insulation of my home over the method to heat. I have another quote on geothermal that I am waiting for this week to determine it is an option.

Patrick

Our project has seen a couple of delays in permitting and in the bank struggled to find a similar home for the appraisal but all of that should be completed. We hope to receive all need approvals from the city this coming week so we can get started the week after the 4th.

Jason

Jason,

Sounds good on your start date. We've just completed digging our basement. That was a bit more involved with hitting stone at 3'. We were concerned our city fathers might look closely at out all concrete home. In the end we submitted plans and filled out a sheet of basic details. The sheet did not require wall material details, just floor joists. I'm sure as the inspections are scheduled they will get an eye full.

Good luck

Patrick T.

So according to ORNL for a climate like MN I would be best pursuing a concrete interior w/ exterior insulation (stucco or cement board finish)? Gives thermal mass on inside in conjunction w/ passive solar design. I happen to like concrete wall finish. I could see most prefer ICF for interior wall finish to avoid building interior framing. So that could open up doors to precast or poured walls with insulation board attached to the outside? I'd think commercial precast tilt up walls could be used to make an inexpensive modern home. Industrial buildings are all over using tilt up. Concrete block could be an alternative as well. Input?

slenzen,

The list of best thermal mass building methods still depend on if a perticular location if it has Thermal mass benifit, temp swings. Locations with constant temp will not see the same benifit as Arizona high lands. You may want to look at this way, if you can go ice fishing for several months, you probally don't have too much benifit.

As I recall, Northern climates showed small diff between super insulated/sealed convential vs Thermal mass methods.

read through the site, it takes time but's very interesting.

Patrick T.

I'd stay away from block foundations. With our freeze and thaw situation in MN. Block a uniformed pattern and there it naturally has fault lines built into it. Poured walls are more durable and resistant to these effects based on their organic formation.