Like to share my ICF idea.
Last Post 30 Jul 2015 11:54 AM by jess_diy. 17 Replies.
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jess_diyUser is Offline
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09 Jul 2015 03:06 PM
Hello all, I would like to build an ICF house single story around 2500 sf. Reason being is that we want it to be our retirement home, wheel chair friendly. Have lots of ground in the Spokane area, big sand pile. So geothermal radiant heat looks like a good heat source. We have both build block and fox block manufactures with in 50 miles of us. I'm a DIY er but the pour is over the top for me. The question, slab on grade or a suspended slab. I kinda like suspended slab using build deck, the span under slab could be anything since its a crawl space. In my thinking using 6" build deck would give me close to an R50 floor and could add more EPS sheets if needed. Would have really good thermal mass in the floor and of course pex hydronic radiant heat. Plumbing and electrical would also be easy under the suspended slab. So if I did do a suspended slab, 1. poor the footing 2. short stem wall 3. slab tied into the steam wall 4. finely the walls. Sound like a good plan? Jess
thermalenvelopeguyUser is Offline
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09 Jul 2015 05:23 PM
Jess, Sounds like you have the sequence correct. I am planning a similar structure myself. At first, I was thinking slab on grade, but I am thinking about a suspended slab too, because I like the idea of being able to gain access under the floor. Bracing the upper walls from the slab will provide a good working surface and your cold joint can be at slab level. However, I believe the slab on grade would save enough money to warrant serious thought. Eric
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13 Jul 2015 07:48 AM
There are products out there made for insulating the slab and that also have radiant tubing attachment already in place. BuildDeck would be way overkill when you can get as good of results for $1 a sq/ft with a simple 2 inch or less EPS board.
Ladwig Construction<br>Hennessey, Oklahoma<br>405 853 1563<br>Residential and Commercial Contractor<br>ICF's and Steel
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13 Jul 2015 09:49 AM
I have to agree with joasis, however suspended concrete floor systems are excellent floors, would there be another floor elevation, if you are going to use it for that level as well? kind of might make more sense. if you are going to to do a crawlspace - what is your frost elevation, if its 3ft or more its not much more to just do a a full basement, thats usually the main issue with a crawlspaces, just a couple more feet and you have a full basement. Crawlspaces in general, even with standard floors, are usually not a good option and tend to be one of the lower ROIs. Unless you have flood plain issues etc it might make sense, but then your frost level is typically small.
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billnaegeliUser is Offline
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13 Jul 2015 09:49 AM
I have to agree with joasis, however suspended concrete floor systems are excellent floors, would there be another floor elevation, if you are going to use it for that level as well? kind of might make more sense. if you are going to to do a crawlspace - what is your frost elevation, if its 3ft or more its not much more to just do a a full basement, thats usually the main issue with a crawlspaces, just a couple more feet and you have a full basement. Crawlspaces in general, even with standard floors, are usually not a good option and tend to be one of the lower ROIs. Unless you have flood plain issues etc it might make sense, but then your frost level is typically small.
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jess_diyUser is Offline
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15 Jul 2015 04:20 PM
joasi / billnaegeli,

The footing depth is required to be at least 24" but looks like 36" is what the builders are doing. The reason I would want to do an elevated slab is for the thermal mass, again hydronic radiant heat. I could do slab on grade with good geo EPS foam under slab with good results and lower costs. This is probably the wrong area of the forum But.
If I go with ICF 32" below grade the fill would be silty sand ( whole property is this type of soil, flat and about 17" of rain/snow year), I know I would gain a certain amount of thermal mass in the sand. How much, don't know.
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15 Jul 2015 05:01 PM
Question, jess. What is the design temperature range for Spokane? When you say geothermal are you referring to heat pump with water source, or natural hot water?

I built my house in Parma, ID where the low temp went to -10°F these past two winters, and high has been over 100°F. I considered radiant floor, then radiant ceiling for heat and cool, and finally went with a Daikin air to air heat pump. The air handler is in the crawl space with short ducts in 3 directions. The crawl space is sealed with a concrete over insulation "rat" slab. The floor is Advantech subfloor on I-joists with hardwood and tile with no insulation. The roof is foam insulated underneath the decking and I use the attic for the return plenum. The end result is a quasi-radiant heated floor, warm or cool air circulating through the house constantly, no cool or hot drafts, and very comfortable uniform temperature throughout the house all year. I have no water system to contend with, and the Daikin system is quite reliable.

With my system there is no need for R50 insulation under the floor. Heat loss downward from the house is not great, even though the crawl space is about 80° in the winter.

In short, in my experience and opinion radiant floor heating is a great system, but more than is warranted for an ICF house. Also, sand and soil are not that great for thermal storage.

Even a retired engineer can build a house successfully w/ GBT help!
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16 Jul 2015 03:24 AM
Temperature is about 10 in the winter and 95 summer. Yes a water to water heat pump system using a ground loop. Got a hold of a Manual J program was playing with stick built verses ICF. The heat load for stick build is just under 5 ton and the ICF is just over 3 ton in the size of house we are thinking about ( Lots of variables here please be kind). Difference in price is about $2,000 for the heat pumps. Power to run the pump is really cheep in the Spokane area and the COP would be around 3.

Yes I have thought about an air to air heat pump using Daiki or Mitsubishi. The wife is the reason for radiant heat, She has bad allergies and a circulation disease. I have also researched air to water heat pump's and both Daiki and Mitsubishi build them but so far available outside of the US only.

Cooling the house is a no brainier, Spokane is the low 60 summer time nights, Need to change over the air for air quality . With a ICF house just pump the house full of cool air at night and keep it closed up during the day.

More I think about it, ditch the elevated slab and go with an insulated slab on grade.

Dmaceid Do you ave a your system posted somewhere, I would like to read about it.
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20 Jul 2015 09:55 AM
The footing depth is required to be at least 24"...
Unless you use a frost protected shallow foundation. Then it is much shallower.

With a ICF house just pump the house full of cool air at night and keep it closed up during the day.
But don't count on this in other places where humidity is high.

I agree that radiant is less valuable in well insulated homes and milder climates. And it's unfortunate that more air->water heat pumps aren't available in the US. A mini-split in the crawlspace sounds like a great idea - both for distributing heat and for some radiant comfort.
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21 Jul 2015 12:20 PM
thank you, jonr
went back and re read dmaceld post, would be an easy build. I like the simplicity if it.
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21 Jul 2015 08:00 PM
Posted By jess_diy on 21 Jul 2015 12:20 PM
thank you, jonr
went back and re read dmaceld post, would be an easy build. I like the simplicity if it.
I'll have to go back through my posts to see which ones will give a more complete explanation.

Is your wife's allergy related to dust? If so, opening windows at night will be a detriment, I think. We almost never open windows because there is so much dust around us in the summer. As a result all my window screens are still in the garage attic! I have an Ultimate Air energy recovery ventilator. It has the option to run the blower without revolving the heat exchange wheel. I have a thermostat in the incoming air, and a second thermostat in the hallway. When the outdoor temp drops below about 70°, and the indoor temp is above 75°, the ventilator runs exchanging cool outside air for warm indoor air. The only downside is the capacity in this mode is only about 1/10 of what I wish it was. It wouldn't take much to use a furnace blower to do an air exchange at night in the same fashion.

We have a cleaning lady come in once a month but she made a special visit to clean all our woodwork last week. First good cleaning since we moved in in April, 2009. She was amazed at how little dust there was everywhere. With a tight ICF house with a good HEPA filter, or electrostatic cleaner, in the heating/cooling system I really doubt your wife would have a significant dust allergy problem. I have registers in the floor and return grills in the ceiling around the perimeter of the house. We never feel any air movement except when a ceiling fan is on!

The only hitch I ran into with my approach was with the NW Energy Council criteria for Energy Star rating. The guidelines don't recognize using the crawl space and attic space for air flow and the local rep said he was too busy to pursue a technical exception. Perturbed me so I decided to forget about going after a rating. I know I could have gotten it with no problem but I didn't feel like fighting the system.

Even a retired engineer can build a house successfully w/ GBT help!
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21 Jul 2015 08:41 PM
Posted By jess_diy on 16 Jul 2015 03:24 AM
Dmaceid Do you ave a your system posted somewhere, I would like to read about it.
Here's a list of threads where I've posted comments about my system. These should give you a little better picture of what I've got, but no guarantee! They are in no particular order of potential worth to you. You will probably have to move back through the thread to find my post. You'll have to copy and paste the links since the forum s/w does not automatically create links.

Any chance you could create an excuse to travel down this way? I'd be more than happy to have you come by so I can show and explain what I've done.

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/56188/afv/topic/afpgj/5/Default.aspx#40711

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/68189/afv/topic/afpgj/1/Default.aspx#49565

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/63569/afv/topic/afpgj/2/Default.aspx#46248

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/78680/afv/topic/afpgj/2/Default.aspx#80554

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/78428/afv/topic/afpgj/1/Default.aspx#75845

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/78217/afv/topic/afpgj/15/Default.aspx#75542

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/80870/afv/topic/afpgj/3/Default.aspx#103937

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/80538/afv/topic/afpgj/5/Default.aspx#100361

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/80014/afv/topic/afpgj/4/Default.aspx#94118

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/82707/afv/topic/afpgj/1/Default.aspx#126536

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/82417/afv/topic/afpgj/4/Default.aspx#123703

Even a retired engineer can build a house successfully w/ GBT help!
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22 Jul 2015 12:50 PM
She is allergic to just about everything, poor gal. dmaceld, thank you for posting the links. One of the questions I have is the air distribution from your air handler uses three short runs, How did you incorporate the wall mount's into to this or did you use another type of air handler? If I go with the mini splits yes I would use the AC portion. From what I understand with hydronic radiant you have to watch the dew point or you start getting into condensation problems pumping chilled water, that where the open window comment came from. BTW thank you for the offer, not down there very often.

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22 Jul 2015 02:53 PM
Posted By jess_diy on 22 Jul 2015 12:50 PM
She is allergic to just about everything, poor gal. dmaceld, thank you for posting the links. One of the questions I have is the air distribution from your air handler uses three short runs, How did you incorporate the wall mount's into to this or did you use another type of air handler? If I go with the mini splits yes I would use the AC portion. From what I understand with hydronic radiant you have to watch the dew point or you start getting into condensation problems pumping chilled water, that where the open window comment came from. BTW thank you for the offer, not down there very often.

I considered multiple wall units but just couldn't get the the unit capacities and heating/cooling loads around the house to coincide well enough. Total load is only one consideration. Different parts of a house will have different loads based on windows and house orientation. I used one 36,000 Btuh Daikin ceiling unit because it is designed for duct connections on both the inlet and outlet. I have it suspended in the crawl space. The three short ducts are on the outlet. The inlet is connected to a duct that runs from the attic space to the crawl space through the laundry room. A filter box for a 4" HEPA filter is in the duct in the laundry room. One big advantage of this setup is continuous air circulation, 24/7. The system is virtually silent, especially on low speed. We can barely hear the air handler when it is running on high speed, and then only if I stop and listen for it.

Hydronic radiant cooling, particularly in the ceiling, is used quite a bit, I understand, in Europe. A European company has a US presence. It's Bekausa.com. I was planning to use their tubing system until I learned about the Daikin system and decided to go with it. Less complicated. Avoiding condensation is a critical design consideration and requires a balance between loop temperature, expected humidity, and total cooling load. Get it wrong and you could easily have a damp ceiling! Radiant cooling is not recommended in the floor because of comfort issues.

As you can tell, I am really happy with the way it all works. The only improvement would be to install a higher capacity air exchange system for nighttime cooling in the summer.


Even a retired engineer can build a house successfully w/ GBT help!
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22 Jul 2015 02:58 PM
I just looked at the Bekausa website. It looks like they may not have much of an active US presence currently. Not surprising considering the slump in the economy for so many years.

Even a retired engineer can build a house successfully w/ GBT help!
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28 Jul 2015 12:38 PM
I started a new tread in Green/Energy-Efficient Design and Planning " conditioned crawl space/attic and mini splits" I think it fits better here.
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30 Jul 2015 10:14 AM
The inlet is connected to a duct that runs from the {conditioned} attic space to the crawl space


I'd be interested in knowing if this depressurizes your attic and pressurizes your crawlspace and therefor has a bad effect on infiltration and wall moisture. I believe that many smart phones now have a sensor accurate enough to measure this.

Radiant cooling (including thermal mass passive) works when combined with some dehumidification (typically as part of the ventilation system), slightly positive room pressures, good air sealing and low perm walls/ceilings. Or in a dry climate.
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30 Jul 2015 11:54 AM
Jonr,
'd be interested in knowing if this depressurizes your attic and pressurizes your crawlspace and therefor has a bad effect on infiltration and wall moisture.

yes I would think this would happen but in my mind the ICF is the game changer. ICF from what I understand are ultra tight and from reading somewhere, conventional construction you need to control the wall moisture on the inside and ICF on the outside. Also have the proper air change humidity control.

Radiant cooling (including thermal mass passive) works when combined with some dehumidification (typically as part of the ventilation system), slightly positive room pressures, good air sealing and low perm walls/ceilings. Or in a dry climate.


ICF should work for the sealing part, then install dehumidiffier with a HRV?
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