From $9.95


Statistics

Users
Total: 32,935
Visited Last 30 days: 194
Forum Messages
Total: 20,968
Last 30 days: 7
Forum Evaluations
Total: 24,160
Last 30 days: 0
Journal Entries
Total: 5,401
Last 30 days: 8
Connections
Total: 15,247
Last 30 days: 4
Downloads
Total: 87,234

Journals

Name
getpestcontrol Delhi, AL
45 Visits | 2 Posts | 1 Pix | 0 Videos
NorthShoreBathrooms
20 Visits | 1 Posts | 2 Pix | 0 Videos
Tenants-Right-When-S... Maryland, MD
618 Visits | 5 Posts | 4 Pix | 0 Videos
furnacerepairon St Catharines, AL
43 Visits | 1 Posts | 9 Pix | 0 Videos
furnacemkm Markham, AL
41 Visits | 1 Posts | 7 Pix | 0 Videos
vallejocleaningservi... Vallejo , CA
40 Visits | 1 Posts | 1 Pix | 0 Videos
noithattrieugia tphcm, AL
61 Visits | 1 Posts | 0 Pix | 0 Videos
httpownerbuilderbook...
125 Visits | 1 Posts | 0 Pix | 0 Videos
Packers-and-Movers Delhi, AL
397 Visits | 2 Posts | 1 Pix | 0 Videos
Best-Access-Doors Jackson, AL
176 Visits | 1 Posts | 0 Pix | 0 Videos
Concrete-Contractors...
241 Visits | 2 Posts | 0 Pix | 0 Videos
bird Springfield, MO
172 Visits | 1 Posts | 0 Pix | 0 Videos
Tanglewood Colorado Springs, CO
120,482 Visits | 1,004 Posts | 2,581 Pix | 47 Videos
Drywall-Repair-Lehi
250 Visits | 1 Posts | 0 Pix | 0 Videos
ianpundt
292 Visits | 1 Posts | 0 Pix | 0 Videos
Magic-Of-The-SideSto... San Carlos, CA
628 Visits | 2 Posts | 2 Pix | 0 Videos
httpswwwfaxitfastcom... salt lake city, AL
256 Visits | 1 Posts | 0 Pix | 0 Videos
Owning-My-First-Prop... Grand Rapids, MI
378 Visits | 1 Posts | 0 Pix | 0 Videos
movers-and-packers Hyderabad, AL
372 Visits | 1 Posts | 1 Pix | 0 Videos
Investment-Propertie... Rochester, MN
422 Visits | 1 Posts | 0 Pix | 0 Videos
See all journals...

Current Top-Rated Posters

RatingPosts
Lance in Buena Vista, CO0.002

Great forums with lots of info. I want to do this right the first time.
David in Haltom City, TX

Try one of our new Construction Bargain Strategies for free. Coupon code: CBS. One strategy could save you $1,000 or $10,000 or maybe $50,000 when you build or remodel.
25,000 pages of free owner-builder resources.  We accept no ads.

Thermal Mass Example


Filter by date: and/or Keyword



Reply... Subscribe to this topic

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 2/20/2006


I've started getting some really fantastic information on my ICF walls. This is a 12-hour graph from this week (Tuesday). During the day we had almost 70-degree outdoor temperatures, and then that night, we hit single digits. This is the extreme case of thermal mass, but from the graph attached, you can see the sun set at 5:30 (significant drop in temperature) and the temperature of the thermal mass continues rising for several hours before starting to cool slightly. 

For this instrumentation, my indoor temperature is measured in my back hall where I have a weather station mounted; it is a lot of west-facing glass, and tends to pop about two degrees during the day, whereas the rest of the house is more constant. We typically see the indoor temperature vary from 71 to 73 (my wife likes it warm).

In this graph, you'll notice after the sun goes down, the indoor temperature is virtually constant. In this type of scenario, we usually see the boiler turn on around 3:00 am for an hour or so, and then usually stay off, even in sub-30-degree temperatures, until the morning sun takes the heating responsibility over via passive solar.

I've got lots of other stuff to share. One decision I'm going to try to make with this is if I should roll my black EPDM roof with a solar-white type product. I could get thicker, better roofs with longer warranties in black, so I elected to install the black roof, then roll white liquid EPDM over it, adding a layer of protection to the real roof, and reflecting sun. I've not done this yet, but am going to try to evaluate the winter benefit (the hotter roof surface temperatures reducing the entropy/heat flux via the attic) versus the summer heat increase. In a 50/50 climate, it would be a toss-up, but I'm not sure... I may just have to wait a year to get better data on that one. We have huge amounts of east-facing glass, and a fair bit of south glass (views on both) so summer gain is slightly higher than I'd like (we get into mid-upper 70's) but we don't have these windows screened from the high-angle summer sun yet...

The last five days we have been in single digit and minus temps, so I'll add more data. I think the thermal mass is less optimized in those cases, but interestingly, the core (concrete) temperature only varies by a few degrees... Temperature swings are free reloading of the flywheel, and are best, but not exclusive.



Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 2/20/2006


John,

Can you give us some design parameters of your wall system?

How thick and what type of insulation is the block? How thick is the concrete? How much steel is in the system?

An upload of your floor plan (small size file please!) would help with understanding solar gain and earth protection.

Any additional info on orientation, window performance and roof structure will help shape the discussion of how the entire building envelope works as a "whole".

Thanks.

Reply...

2004, 2005, 2006, 2007, 2008, 2009, 2010 Merit Award Winner
Contributing Editor

Kenneth's Forum Posts: 937
Interview Answers: 181

Private Message


Randomly Selected Image

Login to Vote

By Kenneth in Lees Summit, MO on 2/23/2006


John,

 

Great data. Kind of makes me wish I would have instrumented my house. How much HVAC intervention and at what times are you getting it? You temp-in stays +/-2 F even as your delta between temp-in and temp-out ranges from almost nothing to >40, yet this doesn’t seem to be a factor for temp-in. It would appear that you get some HVAC intervention at between 21:00 and 22:00 as the temp-in slope levels and perhaps even starts to trend upward and you certainly aren’t getting any solar effects at this time.

 

I don’t get as much temp-out swings as you do over the course of a day, but I find that without HVAC intervention my temp-in (using your data definitions) range is ~+/-4 F (whereas yours is +/-2 F). At night my delta between temp-in and temp-out is routinely >40, similar to what you are showing. I also find that wind is not a significant factor.

 

I use a forced air HVAC, which is different than your hydronic, but I also find that it primarily operates in the morning as we prefer to sleep in a cooler environment and would like to lose more heat (we keep the shades drawn in the bedroom to minimize daytime solar gain). I never thought I would say that I am disappointed because I would really like to lose more heat at night when my HVAC isn’t even operating. On cloudy days, we get occasional HVAC intervention after the sun goes down in the evening, but this is infrequent. The other day, my HVAC actually came on during the day (!!!), but my delta between temp-in and temp-out was >60 and it was cloudy, which is an extreme in my environment for daytime temperatures.

 

Some additional data points. My floorplan and orientation is on my website, light-colored roof (Tamko OE Pewter), R-50 dense packed cellulose attic insulation with a well-vented attic, low-E windows for maximum solar gain with cellular shades at night, 6” concrete core ICF with #4 steel ~16 o.c horizontal and ~24” o.c. vertical on the main level and 8” concrete core with more vertical steel on the lower level, 2-1/2” foam on interior and exterior (Amvic ICF). In my environment, most low-E windows are for minimum solar gain (heavier cooling environment), but I wanted maximum solar gain because they are shaded from high angles during the summer.

 

Just to add a data point from my old house, we had an ice storm and lost electrical power so no HVAC for four days. During the sunny days, it would get to 70 F inside from solar gain, but once that sun went down it would get !@#$%^ cold quickly. We were in bed by 8:00, down comforter and two fairly large dogs in the bed just to keep warm. This is typical stick-framed, R-13 walls, R-30 roof, no thermal mass, and the temp-in range over the course of one day is probably +/->20 F without HVAC intervention. This is the same environment I am in now, so it offers a valid comparison to my new house.


Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 2/23/2006


I need to get my boiler data graphed against this graph - I have it all in data files, I just need to build a routine to graph the two in one place.

I'll get a floorplan up. It's a piece of my system (a floorplan that shows real-time temperatures) I've not worked on, but a few bits about my system:

The basement is 8" concrete, 2 5/8" thick foam (each side) Nudura ICF. The main level is 6" concrete core, same foam, Nudura ICF. My attic is insulated with 11" of biobased spray foam applied to the underside of the roof deck. We are situated on the first foothill of the mountains, looking out at the plains, so our east-facing wall picks up sun exposure starting first sunrise, which I've found seems to support slightly higher ICF wall temperatures than even the south wall.

My house is a Santa Fe adobe style, with a flat roof concealed within the ICF walls. My attic, before insulation, ranged from 18" at the low area, to 30" at the peak. With the attic effectively "conditioned", heat from cans, etc. is contained within the attic. However, the attic air temperatures do not seem to move at all with cans on/off, so I suspect the overall contribution is small.

My roof is currently black. I've got some graphs of my attic temperature (air temperature, conditioned air) vs. the sheathing temperature I'll post, too.

On this particular night, we had a big front of arctic air hit which subsequently held air temperatures (outside) in the single digits or sub zero for days. I can correlate this to my weather data, but I wouldn't doubt some intervention that night.

If I could get away sleeping cooler, I would!

I need to add one more sensor too; right now, we use the hot water on demand feature of our boiler for domestic hot water, i.e. tankless. So washing dishes looks the same as HVAC heat on my graphs. With a temperature sensor on the DHW line, I can distinguish between the two.

I'm currently testing/correlating this system with my monthly propane use. I'm measuring the output of the boiler (it modulates, so it might be on, but at a low 'power') and integrating that, using the "standard" BTU output of propane and known boiler efficiency curves to try to "predict" my bill real-time... Once I know my daily usage, for heat, I think I can build a function predicting use given an average daily temp.

All of this, besides an interesting academic exercise, is hopefully going to allow me to put the boiler into backup duty and add a properly-sized active solar system to the hydronic heat. I really didn't know what the use would be, and didn't want to delay getting into my house, doing solar up front. The boiler was the quick way in, and will be a nice backup should the clouds hit.

I'll try to shore this up later this week. Thanks for the great input!

Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 3/15/2006


I had been meaning to update this with some more information... Some of these graphs have some aliasing, as I've been playing with some control algorithms and using the econo-cool feature of my HRV just to see what kind of transfer function describes the cooling ability.

The first graph here is a two-week period of typical Colorado spring weather, followed by a cold storm, which we are starting to come out of. I've superimposed a boiler run state (light blue) but it does not show the modulation (45K-200K Btu), so it's not all that helpful, except that you'll notice that the boiler is almost always a late evening/early morning run time. The boiler also runs for hot water demands (on-demand only) so dishwashing/showers show up in here too.

Notice the sinusoidal nature of the ICF concrete walls (blue/green/yellow). The peak temperature of the wall occurs shortly after the sun sets for the night. The integral area under the curve until the next morning is essentially energy that is dissipated ~1/2 through the outside foam to the environment and 1/2 to the inside. I think this is key to high thermal mass designs (adobe, AAC, ICF). Although each 'insulation mode' has some advantages/drawbacks, the nature of the graph is a good talking point for thermal mass in general.

It takes several days for the ICF walls to cool significantly, but they do trend downward. If I were building in an area with consistently cold or consistently hot climate, I'd probably consider either uninsulated concrete, very thick (for hot) or SIP, with solar/passive Trombe/internal thermal mass.

The second photo here is the cellar telemetry. This measures the open air temperature in the ceiling of the wine cellar, along with the outside temperature. Currently the cellar is ICF on four walls, with a steel door, an ERV exhaust with a fresh-air intake from the basement, and a 12" thick concrete roof with a black EPDM roof. The roof will be covered by stamped concrete when the freezing quits around here. The time constant of the concrete is huge, and the interior temperature of the cellar is maintained very nicely, with no HVAC other than a few CFM of stale air exhausted every 6 hours by the ERV.

Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 3/15/2006


In this graph, which is not thermal mass, I have the sheathing temperatures of my roof sheathing (under black EPDM) versus the attic air temperature immediately inside the 11" of biobased spray insulation applied to the underside of the roof decking. You can see where we move into a steady state (constant heat flow from inside the house to outside) during the cold last week, versus the transient period where heat is moving both ways. The overall performance of this assembly would be similar to SIP or spray-foam stick framing, although this has 11" of foam, versus the typical wall assembly, so in a wall assembly the temperatures will track closer together.

Overall, the roof sheathing tends to track the outside temperature, but is much more volatile as the black EPDM roof collects sun during the day. During continued cold, solar radiation gain on the south roof vastly outpaces the north roof, which has significant architectural features blocking it from the southern exposure. Perhaps the best energy balance over the course of a year might be to keep the south/east roofs black, and roll the north roof (the majority of the structure) with white EPDM... Hafta think more on that.

Oddly enough, my south attic has higher highs (as I would expect) and lower lows, than the attic on the north side. I suspect that this may be a combination of factors, including that the boiler exhaust is on the north roof, and the north roof has more protection from prevailing winds than the south roof does.

Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 3/16/2006


John,

Without seeing your roof layout, orientation and what's on it, I would suspect that some of the difference between the two areas at night is the atmospheric heat-sink exposure. Here in Tucson, our night sky is a negative 50-degree heat sink, however all those things that happen on a roof (equip, exposure, color, shading) all have impact on that number.

Reply...

2006, 2007 Merit Award Winner

Jon's Forum Posts: 219
Journal Entries: 1
Interview Answers: 2

Private Message


Jon's Selected Image

Login to Vote

By Jon in Ellicott City, MD on 3/16/2006


I've found some interesting research on thermal mass design.  Like all internet information, I'd treat it with a skeptical eye. But it has given me cause to rethink the subject.

ornl.gov/sci/roofs+walls/research

Among the conclusions...

"Comparative analysis of sixteen different material configurations showed that the most effective wall assembly was the wall with thermal mass (concrete) applied in good contact with the interior of the building. Walls where the insulation material was concentrated on the interior side, performed much worse. Wall configurations with the concrete wall core and insulation placed on both sides of the wall performed slightly better, however, their performance was significantly worse than walls containing foam core and concrete shells on both sides. "

 

Maybe we should rip the interior EPS off of our ICF!!


Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 3/16/2006


I buy that 100%. My dream configuration would have been two adobe walls separated by 4-5" of EPS, but practicality said ICF would be the way to go, for cost and schedule reasons. :)

With the EPS on only the outside, you wouldn't split the integrated energy under the curve 50/50 with the outside, it would be directed inside, and thus, more efficient.

Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 4/10/2006


John... I have some good news and bad news for you.

The Amvic factory rep was here in AZ recently and I told him about your project and monitoring. That's the bad news. The good news is they want me to expand this data discussion and during USGBC Greenbuild this November have you come to their side gathering and discuss your project...

Dale

Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 4/12/2006


The study concludes that concrete/insulation/concrete (CIC) performs better than insulation/concrete/insulation (ICI). Why aren't there more ICF manufacturers/builders using the CIC format instead of the ICI format?

This could be either a prefab concrete sandwich panel or foam panels shotcreted on both sides on site. Anyone aware of any studies or experiences w/these types of building systems? Cost of construction comparisons? Specialized labor required or not? Speed of construction? (time is money) I'm thinking the shotcreting and finishing might be labor intensive. I've only located a few companies that do this type of construction.

Reply...

2004, 2005, 2006, 2007, 2008, 2009, 2010 Merit Award Winner
Contributing Editor

Kenneth's Forum Posts: 937
Interview Answers: 181

Private Message


Randomly Selected Image

Login to Vote

By Kenneth in Lees Summit, MO on 4/12/2006


I would think that part of the reason has to do with the steel in the concrete. My ICF wall uses a 6" core of concrete, plenty to surround the steel needed for large headers (I have some 9' openings) in an ICI package. One of the challenges with a 4" core ICF is getting enough steel in your headers, and getting the concrete to flow around this steel, so for a CIC package you would need at least 4" concrete on each side of the insulation, which is 50% more concrete (not exactly cheap at today's prices).

Then you have concrete interior and exterior, exactly what finishes are you going to use, and how are you going to attach them? What about utilities? You can channel the interior foam for plumbing and electrical (while it is always a good idea to avoid exterior walls with plumbing, you need electrical outlets on all walls). You can screw your sheetrock directly to the ICF, although if you are doing a CIC package and interested in thermal mass perhaps you don't want to cover your interior concrete with sheetrock? Depending on your choice of exterior finish, a solid concrete mass may not be desirable either.

And then there is the finish work. For these concrete walls you would want smooth finish (trowel finish), for ICF walls where you never strip your forms, you pump and vibrate, a much quicker solution.

And finally, the CIC package would appeal to only the fringe. The ICI package using ICF can appeal to the mainstream buyer. If I am in a business selling product, I prefer to cater to the larger market as this poses less risk for me.


Reply...

2006, 2007 Merit Award Winner

Jon's Forum Posts: 219
Journal Entries: 1
Interview Answers: 2

Private Message


Jon's Selected Image

Login to Vote

By Jon in Ellicott City, MD on 4/12/2006


Well, shipping costs would be an issue with a precast concrete "sandwich." People seem very happy with their Superior Walls (another precast concrete product) though, so maybe it isn't such a problem if you live close to a manufacturing plant. Also, you'd need a continuous 4"-5" layer in the middle of the panel if this wall were above grade. With the mass of the concrete "skins", I have my doubts that you could handle the product without tearing it apart. You'd probably need more than just the foam to hold the two sides together (thermal bridge). I'm sure it's a viable concept, but one that's not without drawbacks.

Shotcreting foam panels has it's problems too. First, you'd have to build some substantial support for the foam and the rebar, so the blast of the concrete wouldn't knock it over or destroy it. After one side was coated, you'd have to strip all that temporary framework, wait a couple weeks for the first concrete to cure, then come back and complete the other side. You'd need several inches of concrete to provide the structural integrity required. I'd think it would take MAD skills to finish that much vertical concrete to a smooth/flat/plumb surface.

A much better alternative, IMHO, is to set up conventional steel wall forms and place EPS sheets inside those forms (all the way to the outside surface) and then fill the forms with concrete. This would be quick, easy, and minimize ancillary costs (like shipping or complicated bracing structures). I know these systems are out there. I might have used it if I'd learned of it sooner. My concrete contractor tells me his crew can pour an entire basement this way in about 1-1 1/2 days. That beats the heck out of the time it took me to erect and brace my ICF's!!!


Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 4/12/2006


Regular steel wall forms have ties every few feet to hold the two sides together, so you'd have to use a bigger tie and spear the foam, which would make forming more difficult. But I think that this method is probably the closest way to implement it.

The ties would bridge, but it would probably not be outrageous.

I know there are systems that do this (I believe they pour flat and tilt up), but I suspect their popularity is limited because this is going to be an intensive system to install and finish. Rastra blocks are almost a variant of this, which I had seriously evaluated before opting against it. Rastra is a great product, but is nowhere near as popular as a conventional ICF... Why? I suspect that having to bring in cranes to move blocks around makes installation difficult and expensive. 

I would believe ICI would definitely be better, it was in a way my first choice. But actually _doing_ ICI was a challenge (adobe/insulation/adobe) - The masses of everything start to get really big.

Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 4/12/2006


There are some commercial ICF and SIP buildings here (same builder) that are hoping to implement the monitoring, and do some active solar control. I may have a night job!

Contact me off list if there is anything I can help you out with!


Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 4/12/2006


Thanks for the info! 

With concrete skin SIPs are the concrete panels on each side (especially inside) enough to achieve the thermal mass benefits? Or is it just a heavier version of an OSB SIP?

I was thinking building a modern loft-type construction w/smooth concrete walls or plastered and open utilities exposed steel-beam type construction. I thought maybe these methods would cut some steps in construction and speed things up.

Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 4/12/2006


Justification why they don't do CIC: 1) salable product, 2) ease of construction, 3) labor costs, 4) availability of trained installers, 5) code compliance.

Some of the main points they use to sell ICF are "easy to do and quick".

I have seen ICF walls go up in a matter of days from slab to anchor bolts set for top plate. If you use the correct concrete mix, you can pump a 12' wall in one day.

Structurally, a CIC wall are two separate structures, kinda like a double brick wall. Not good in an earthquake. Getting an engineer to sign off on the building would be an absolute requirement from code officials.

Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 4/12/2006


Concrete SIP's don't have enough mass to be of usable thermal value. Only way to get insulated exposed concrete would be to do AAC panels. Check with e-crete or somebody like that about what they can make. Big issue with concrete walls is getting enough mass to create a thermal time lag. And in Minnesota you would need some very massive walls to provide a K value that would be beneficial.

One way to achieve the look you want would be to do SIP's and apply cement board and plaster finish. Rather than I-beams, use bar joists with an exposed metal deck. Then attach the roof insulation to the outside. They make an insulated sheathing.



Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 4/12/2006


The thermal mass to get the flywheel effect is substantial, SIP skins (unless we are talking 4" thick skins) won't be adequate.

ICF _can_ go up very fast. (Seems like mine, DIY, was around a month per level with rain delays). We (myself and one other person) were stacking a level of my house in three days (two guys) but the bracing (carrying it in, etc.) took forever. My distributor (a former installer) said his four-man crew would finish a level of my house in one week, (then a week off for steel and floor framing) and then another week of ICF, for two weeks total for the ICF's. It took me usually three days for a level, weeks to brace and do blockouts and other small details, and a day to pour. 

Actually, the first pour (basement) took us about 8 hours. Some wall sections were 15' tall (walkout frost wall). That was a tough day, but mostly because the concrete company had us waiting for trucks.

On the main level, we poured 12' and 15' walls in less than 3 hours. 

Now - We are building an SIP house here (spray-foam attic like mine) with a brick exterior, geothermally heated with a 10 kW solar PV array... I won't have the time to instrument everything (like confirming the COP of the geothermal unit) but if we had 10 temperatures to measure, what would we measure... I'll take some input here, and then when I instrument this house, we can try to get some comparisons. (I'm actually thinking about integrating my instrumentation into a plug-and-play system, so it would be easy for anyone to install).

How about:
1) Exterior skin temperature
2) Center of foam
3) Interior temperature.

(Do these for north and south sides).

7) Attic Air Temperature
8) Roof sheathing temperature (concrete tile roof, versus my black EPDM).

Others?

Reply...


Mark's Forum Posts: 72
Interview Answers: 4

Private Message

My Construction Website


Randomly Selected Image

Login to Vote

By Mark in Seattle, WA on 4/12/2006


To the extent that there is any construction difficulty caused by the weight of Rastra, the difficulties can be offset by other benefits. My wife and I can carry the blocks, so it wasn't a problem.

One of the benefits, if you're willing to play to Rastra's strong points, is the thermal mass benefit discussed above. Everyone agrees that mass-insulation-mass is the best thermal mass wall, but shotcrete over the interior of an ICF wall is going to be costly. One of Rastra's strengths is that it can be directly stuccoed and plastered without furring out, lathing, etc. An inch of plaster on the inside a Rastra wall is completely uninsulated thermal mass. 

Plaster on Rastra has more than five times the thermal mass of 1/2" drywall (per Architectural Graphic Standards) and it has no airspace behind it. Stucco (cement-based plaster) has six times the mass. 10 lineal feet of 8 foot tall stuccoed Rastra wall is almost 1,000 lbs of thermal mass. By using stucco/plaster, most Rastra homes would come with tons of uninsulated thermal mass on the interior walls and look very similar to adobe, insulation, adobe. 

I think interior plastering is easier and cheaper than hanging drywall, taping, sanding, etc. Having done it a few times, I'm not afraid to do it again. Finding somebody to do it at a reasonable cost is a problem. A one-coat stucco on the outside is a little more work than Tyvek and Hardiplank, but it's definitely cheaper and has a much longer track record.  Again, finding somebody to do it could be a problem.

Mark


Reply...

2004, 2005, 2006 Merit Award Winner

John's Forum Posts: 278
Interview Answers: 69

Private Message


Randomly Selected Image

Login to Vote

By John in Erie, CO on 4/12/2006


Therein is the problem - cost, or finding someone to finish the interior and exterior of Rastra at a reasonable cost is difficult. Anytime you mention interior plaster, even over ICF (interior stucco even) in my area, you are a minimum of $4.75 per square foot of wall, about the same price as exterior stucco. (That is the cheapest I had bid, stucco prices here averaged closer to $8.)

I have seen Rastra sheetrocked using glue, but I don't know what this would cost.


With my design, to get the required strength from Rastra, I would have to cut out the dividers in most of the cells of a significant number of walls prior to pouring... Like Mark said, playing to the strengths would be key to making it cost-effective and a good application... (My walkout basement and sloped lot weren't helping my design). This was essentially turning it into a conventional ICF, with a lot of waste. Rastra was also not cost-competitive with conventional ICF for my project.

Local Rastra plants could help a lot. Rastra's distribution has changed recently, so I'm not sure how it is working now with the 'main' Rastra corporation owning things.

I had the occasion to visit this house during construction.  After I had visited, a fire tore through the area, the Rastra house (barely dried in) was unscathed.

Very cool (page through the pictures):

mmcmillen.com/rastra/pages/08fire

Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 4/12/2006


How about removable forms, cast-in-place construction w/insulation on outside? What are benefits and drawbacks to this type of construction?

Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 4/12/2006


This would work. You might try talking the form setter to push it out a few inches and use the insulation board as the direct contact form on the outside of wall. This would make it easier to remove forms, and insulation is attached to the concrete. You might want to shoot (or push) nails/screws through the insulation to stabilize attachment prior to form assembly.

Reply...

2006, 2007 Merit Award Winner

Jon's Forum Posts: 219
Journal Entries: 1
Interview Answers: 2

Private Message


Jon's Selected Image

Login to Vote

By Jon in Ellicott City, MD on 4/13/2006


I found a couple of websites that should be of interest to those in this discussion.

First is a very interesting "sandwich" product. It looks like you can use it in a tilt-up application, as a precast system, or use standard steel wall forms with a special tie to hold the foam in the middle of the wall. Very cool!

thermomass.com

I thought the second was a precast system. But the more I look at it, the more I think it's poured horizontally on site, then tilted-up to vertical.

solarcrete.com/insulated-concrete-wall

Dow also makes a product that's designed to go inside pour-in-place walls.

building.dow.com

Finally, here's an article on a builder's site that discusses the topic.

housingzone.com/article

It all looks rather intriguing to me. I had planned on using a combination of ICF and SIP for my above-grade walls. I may have to consider these CIC systems, if I can work out the details.


Reply...


Mark's Forum Posts: 72
Interview Answers: 4

Private Message

My Construction Website


Randomly Selected Image

Login to Vote

By Mark in Seattle, WA on 4/13/2006


A Rastra project in Seattle had a simple solution to the cost of stucco application on Rastra, though it may be politically incorrect now with the present immigration issues. They went down to the local Manpower center and hired a crew. These are the same guys that hang out at your local Home Depot. A surprising number of these guys have stucco/plaster experience, probably over adobe or concrete block, but a straight wall is a straight wall regardless of what's under it. Having learned stucco/plaster myself as a pick-up worker, I know that 50% of any work crew can be good at stucco with a week's practice. Eliminating the other 50% and avoiding the week of learning are the difficulties.

They found one guy who spoke enough English to convince the contractor that he really had a lot of plaster experience. I spoke with him several times during the job. He was "Italian," although he couldn't understand a word of Italian. We spoke in Spanish. I'm probably more Italian than he is. He became the "crew boss" and then interviewed the three other guys who were hired based on their prior stucco experience. 

It took these guys about a week to do 2,000 sf of exterior stucco, so that's about $1-$1.50/sf, not counting material, which is about 30 cents/sf (I can't find my RS Means book right now). The "Italian" even convinced the general to adopt some of the third-world stucco practices he knew. To each batch of stucco, a gallon of acylic paint (bright orange) was added, thereby coloring the stucco. The finish, a terracotta color, still looks perfect after two years and there's no reason to believe that will change. So <$2/sf for the complete cost of a maintenance-free, long-lasting, fireproof siding over ICF. Something to think about.

As to modifying ICF blocks for lintels, etc., the new International Residential Code has prescriptive tables that are based on destructive testing by HUD of the various ICF types. The old method of building lintels was based on ACI tables for solid concrete walls. The theory was to just make your screen grid ICF a solid ICF in certain areas and then use the ACI solid wall tables. Now, instead of cutting out the "nodes" that hold screen grid ICFs together, there are simply prescriptive rebar schedules and lintel depths that address openings up to 12 feet wide. This information has greatly reduced both stacking time and the number of blowouts in screen and waffle grid ICFs. More to think about.

Here's a picture of the "old school" lintel modification on Rastra. This lintel, on the second floor over a stairwell, had some much material removed and so much rebar that it was a real rat's nest. It blew out during the pour. I got in on shoveling up the concrete, carrying it up the stairs in five-gallon buckets, and pouring down a different section of wall while the blowout was repaired. Good thing that they had a huge crew that day. I learned that I'm only good for three trips running upstairs with a five-gallon bucket of concrete before I need a five-minute break.

Mark


Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 4/13/2006


Jon, that thermomass does look good. I wonder what the building cost comparisons are for that. It might work for my contemporary simple loft-type construction. The ties terminate in the concrete, so probably not much thermal bridging. Boone, Iowa isn't far away from me in MN. It looks like it takes extra planning to locate all your wiring conduit and boxes in the form before the pour. Otherwise, it's exposed utilities as an option. There are a couple companies in MN that can probably do the same. I live near Fabcon.

The Solarcrete is a shotcrete system and not a pour-in-place or a tilt-up. That type of construction really makes sense when you visit the websites, but gurus here made some real good points on the cost of shotcreting and finishing.

The companies that use Styrofoam panels for the roofs must be able to shotcrete the top portion w/under bracing and let that harden, and then come back and shotcrete the inside after taking off the supports. I read where they shotcrete the ridge beam first and then are able to proceed w/a hardened beam and bracing.

Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 8/16/2006


I have read that in cold climates such as Minnesota where you might get extended periods of cold that thermal mass loses its effectiveness.   Most of the year there are decent temperature swings but certain periods in winter can be below freezing for weeks. 

Reply...

2007 Merit Award Winner

Dale's Forum Posts: 380
Interview Answers: 59

Private Message


Randomly Selected Image

Login to Vote

By Dale in Richland, AZ on 8/16/2006


Your take on the thermal dynamics is partially right and partially wrong. Your thermal mass is a flywheel and the outside environment is a dampening or accelerating force.

The thermal mass performance inside of an ICF in extended periods of either cold or heat diminishes with continued exposure. It runs down and then needs to be recharged.

Ideally in those conditions your mass is completely isolated from uncontrolled access to the outside environment. In those conditions you want to be able to provide for solar gain during the winter or heat shedding at night in summer.

There was a solar home design back in the 70's that had a wall of high performance glass with a controllable "insulated shading" device. During the winter daylight you would move the "device', allowing the sun to heat the thermal mass. In their project, it was a stack of 55-gallon drums filled with water. Once the sun moved beyond an effective angle the "device" was replaced, keeping the solar heat gain inside the insulated building envelope.

The reverse is true in the desert with cooling towers, solar chimneys, interior mass and external berms. Except you allow cool to be collected at night, then prevent heat from entering during the day.

The greater the isolation from the exterior environment and controlled exposure, the better the thermal mass serves your needs.

My ideal structure would be a high-insulated envelope with a high-mass interior with tightly controlled introduction of outside thermal influence.

Reply...

2004, 2005, 2006, 2007, 2008, 2009, 2010 Merit Award Winner
Contributing Editor

Kenneth's Forum Posts: 937
Interview Answers: 181

Private Message


Randomly Selected Image

Login to Vote

By Kenneth in Lees Summit, MO on 9/6/2006


I was at a Storm-Resistant Concrete Homes and Buildings Workshop last week, just trying to stay current on concrete technology for residential construction. It has been two years since I poured my ICF house, and a lot has changed.

 

As to the interior thermal mass systems, Integraspec ICF block has an exposed concrete face option – integraspec.com/noncombustible. I am not familiar with this block, but it is basically a site-assembled block, so for this option you would use only one face of the block and the spacer, and use plywood for the other side of the forms that will be stripped. This would give you insulation on the outside, with thermal mass on the inside. I suppose you could put the concrete on the outside, and the insulation on the inside, but why? I know ECO-Block is also site-assembled, and you could probably use any other site-assembled block to accommodate the same results.

 

Locally to me, there is a company using the CertainTeed ThermaEZE system with their aluminum forms. Basically they are a basement forming contractor that has recently gotten into the business of above-grade walls, thereby allowing them more use of their aluminum forms (if you have priced these units, aluminum forming systems are not exactly cheap, so more uses is a good thing to justify investment). These use a web structure with Expanded Polystyrene (EPS) panels that can be located just about anywhere within the traditional forming system. So you can put your insulation at any point within the wall. For a thermal mass system you would want your exposed thermal mass on the inside. The downside here is that the web system doesn’t have nearly as many attachment points as an ICF, limiting your exterior finish options (most ICF have attachment points at 6-8” o.c.). But if you want an EIFS system, this is probably a potential option.

 

And then there is Thermomass (thermomass.com), that uses Dow Polystyrene insulation sandwiched between two concrete panels. This system is intended to be used in conjunction with traditional forms as well. I asked them about steel placement, and how they can accommodate strength in longer lintels (openings) with two seemingly separate concrete walls. They use a fiber composite connector through the insulating panel that holds the two concrete panels in place and supposedly ties them together structurally. This seems a bit spongy to me, especially if you have any seismic codes that might apply where you are building. These are different than the steel ties normally used, and should not result in a thermal bridge. The nice thing about using a system in conjunction with aluminum forms is that you can drop a big vibrator in there and really get good consolidation (with ICF you are pretty much limited to a ¾” vibrator unless you really want trouble).

 

Both of these systems recommend using a skim coat of plaster to finish the inside concrete walls. I didn’t ask for plaster company references, but I know in this market they are limited (this is a different trade than sheetrocking) and much higher installed price. (But then I was looking at blue board, a step that would be eliminated using a concrete substrate). It seem like if you can finish sheetrock, you should be able to finish plaster, but finding a plasterer is a challenge. As to running your electrical utilities on interior concrete walls, I’ll leave that for you to figure out. And hanging anything, well there is always the hammer drill and Tapcon solution.

 

Imagine my surprise when I picked up the local Amvic Block distributor brochure and recognized my house in two different pictures ;-).


Reply...


Mark's Forum Posts: 72
Interview Answers: 4

Private Message

My Construction Website


Randomly Selected Image

Login to Vote

By Mark in Seattle, WA on 9/6/2006


Kenneth,

There is a pneumatic stucco plaster applying device that I purchased. It's kind of a hopper shovel with air nozzles blowing through the hopper. Scoop up the plaster and blow it on the wall, kind of like texturing drywall. It saves a great deal of application labor time and makes it possible for plaster/stucco to be DIY. Messy, but still not as bad as sanding drywall.

I'd be very interested in anything that you've learned about applying plaster/stucco to concrete walls. I just had a concrete daylight basement poured for a two-story shop/garage. In order to keep the basement light, I'd like to direct-apply a light-colored unpainted plaster, but I haven't found any glowing recommendations for products.


Reply...

2004, 2005, 2006, 2007, 2008, 2009, 2010 Merit Award Winner
Contributing Editor

Kenneth's Forum Posts: 937
Interview Answers: 181

Private Message


Randomly Selected Image

Login to Vote

By Kenneth in Lees Summit, MO on 9/6/2006


No textured interior walls around here. Sheetrock is finished smooth, my 'rockers' used a Level 5 finish, which is fully skim-coated with sheetrock compound and very smooth. The plasterers use hand-applied skim coat over blue board, no sanding, and this stuff is as smooth as paper. Even the traditional stucco (which is textured) is trowel applied. Drywall ceilings are textured with the hopper though; they say it is hard to hide joints in the ceilings.

Given that the rockers could skim-coat a drywall wall, it strikes me as odd that it is a completely different trade to skim coat a blue board wall. It sure looks like the same process to me? Plaster is much more expensive, and much more limited tradespeople locally.

The concrete guys said the finished concrete walls are very smooth (they can even cast in crown molding, painted of course, and not stained). But anytime you pull forms you will have some imperfections and bug holes, especially if your forms are not well-seasoned. This is why they recommended a skim-coat plaster finish directly to the concrete. Again I didn't ask for references, I was only trying to stay current and am not actively pursuing any construction projects in the near future - I'm too busy enjoying the one house I built to dive into this project again anytime soon.


Reply...


Jonathan's Forum Posts: 5

Private Message


Randomly Selected Image

Login to Vote

By Jonathan in Las Vegas, NV on 10/13/2006


Mark,

I can give you a glowing recommendation for GigaCrete---specific to what you are saying in this post, is MegaProtector.  It is naturally a light buff color, but a small amount of titanium dioxide would make it white.


Reply...


Jere's Forum Posts: 45
Journal Entries: 6
Interview Answers: 137

Private Message


Image from Jere's blog

Login to Vote

By Jere in Ray Twp., MI on 2/14/2009


The Solarcrete has my interest... for anyone what has used it, what is your experience?

Jere


Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 3/11/2009


metrockscip.com

strataus.com

These are two interesting CIC systems that seem to have the seismic strength capability.

Reply...


Jonathan's Forum Posts: 5

Private Message


Randomly Selected Image

Login to Vote

By Jonathan in Las Vegas, NV on 3/11/2009


As to seismic-resistant structures, also look at casthome.com.

Reply...


Jonathan's Forum Posts: 5

Private Message


Randomly Selected Image

Login to Vote

By Jonathan in Las Vegas, NV on 3/11/2009


I would agree it is a "good way" but not it is the "only" way.

Look at micro-encapsulated phase change technology.

I am not here to advertise, but let me know if you need help with the research.

I do not sell the product--I do research and development in the ceramic cement arena.


Reply...


Steven's Forum Posts: 51
Interview Answers: 60

Private Message


Randomly Selected Image

Login to Vote

By Steven in MN on 3/11/2009


Any links to info about micro-encapsulated technology as it relates to building?


Anyone doing similar to the casthome lightweight concrete in the US? Kind of like AAC?

Reply...


Jonathan's Forum Posts: 5

Private Message


Randomly Selected Image

Login to Vote

By Jonathan in Las Vegas, NV on 3/11/2009


Yes, I do, and there is a fellow in Santa Fe named Steve Brenna who does.

It is my understanding that Litebuilt, litebuilt.com, has some representation in the US.

This is like AAC, only much more versatile. I personally can go from 5 lbs. per cu. ft. to full density and this is done either in a precast situation or on site.

I am not here to advertise my own personal system, but I will be glad to advocate for anything concrete.


Reply...


Jonathan's Forum Posts: 5

Private Message


Randomly Selected Image

Login to Vote

By Jonathan in Las Vegas, NV on 3/11/2009


Links to phase change are numerous. Here is a good starter.

peswiki.com/Phase_Change_Material


Reply...



Reply... Subscribe to this topic

Copyright 1997-2020 Consensus Group Inc.