http://inspectapedia.com/Energy/Insulation_Polyisocyanurate_Slab.htm
I love this website this is the picture that inspired the way I drew my slab, not sure if I done it right or should I do more like you described, I'll put it on paper when I get a chance see which scheme feels right

Posted By arkie6 on 25 Jan 2014 10:12 PM

On the walkout side of my basement, my footings are only ~12" deep because that is all that is needed down here.  I installed 3/4" clean gravel flush with the top of my footings on the inside.  Then I covered that with 10 mil vapor barrier, then 1" EPS foam up to the forms where my walls would start.  This 1" EPS foam covers the inside ~6" of my footings so the slab rests on top of the foam rather than directly on top of the concrete footings.  My footings set on undisturbed earth.  Actually, because of a lot of rains that we had prior to pouring my footings and the clay we have down here, I rented a jumping jack and tamped inside my footing forms prior to pouring the concrete.  Also, I used fastfoot fabric for my footings.

Here are my footings:  http://www.fab-form.com/fastfoot/fa...nSmith.php

The footings seem reasonably sized for ICF. How wide were they?

So is your slab technically a "floating slab"?

How many inches of 3/4" gravel did you install?

Any pics?

I was kindof growing fond of the angled glass I liked it honestly, I drew this last night based on some of the disscussion here and other forum on angled glass, and drew it vertical instead, that alone simplifies the build a lot the third row of posts were there in the old one just to prop thet wall of glass up so I eliminated a third of the foundation work, some of the concerns that were brought up about sagging and sealing are much eliminated, I also moved the 2 ft rammed earth on the outside of the framework and gained some square footage , as for the roof I left it at 12 inch thick aprox R48 on a bad day, floor is about R24 and so are the walls, I read a bit on some of the work the sweedish have done particularily insulated shalow foundations, and drew mine like, I need to do more reading into the pasivehous came across the name briefly need to know more. in the end I am growing quite fond of this new drawing, maybe I'll have to tweek it some maybe more insulation in the roof, the winter sun exposure diminished a bit part because the 4 ft wall on the south side is closer to the living space but I can live with that most of you thought it was too much before even now still, I can live with it considering all the headackes it eliminates, and honestly I am not sure if heat gain in the winter will be affected at all due to the vertical angle but in the sunmer solstice sun the glass is at a much shallower angle hopefully bouncing off more light than it alows in, ( I know don't hope, rough gutt feeling for now once I decide on something we'll see about the math ) thanks to all that pitched in Read more: http://priuschat.com/threads/earthships.136092/page-4#ixzz2rnrasSy3 Follow us: @PriusChat on Twitter | PriusChat on Facebook

About the only thing worse than angled glass is sky slights. Both are hard to control and both tend to do the opposite of what you want with regard to BTUs.

To properly design a passive solar building you need to accurately forecast the BTU input/output for the given building design (i.e., actual roof overhang and fenestration parameters) to minimize control variances. To achieve the required accuracy, you really need to do this every couple minutes of every day and then integrate the results. Even our simple DIY passive solar software does this (i.e., 1/10 hour or 6 minute time slices). And finally, the design needs to be able to address/control the daily variance between these forecast BTUs and actual BTUs (i.e., between maximum clear sky and actual climatic solar conditions, and between design outdoor and actual outdoor temps).

You really don’t want to just put your thumb in air when designing passive solar buildings.

George, love the learning attitude and desire to understand and design DIY, but....

If passive solar can (typically) only get you to 50% space heating, and you are still buying kWh for appliances, why not build a Net-Zero house using a more off the shelf plan/approach?

It's a long way from an earthship to a 2014 Net-Zero house. Why don't you start with Net-Zero, and then tinker and have fun from that design starting point?

If money is an issue, why not build a 'Pretty Good House', and add the solar later? And cost of ownership would be lower than what you are trying to design anyway?

Posted By sailawayrb on 30 Jan 2014 09:08 AM
About the only thing worse than angled glass is sky slights. Both are hard to control and both tend to do the opposite of what you want with regard to BTUs.

To properly design a passive solar building you need to accurately forecast the BTU input/output for the given building design (i.e., actual roof overhang and fenestration parameters) to minimize control variances. To achieve the required accuracy, you really need to do this every couple minutes of every day and then integrate the results. Even our simple DIY passive solar software does this (i.e., 1/10 hour or 6 minute time slices). And finally, the design needs to be able to address/control the daily variance between these forecast BTUs and actual BTUs (i.e., between maximum clear sky and actual climatic solar conditions, and between design outdoor and actual outdoor temps).

You really don’t want to just put your thumb in air when designing passive solar buildings.

I'm still trying to wrap my head arround your aproach, this is all new to me, I was reading last night about passivhaus how they were able to calculate all losses before the building went up and then the measurements confirmed the calculations were acurate. I can see now how angled glass and skylights for that matter can be problematic, glad you all pitched in on that, to forecast btus every 2 minutes for a imaginary building sounds like a lot, heard there are some softwares to help with that. still looking into that

Posted By woodgeek68 on 30 Jan 2014 09:39 AM
George, love the learning attitude and desire to understand and design DIY, but....

If passive solar can (typically) only get you to 50% space heating, and you are still buying kWh for appliances, why not build a Net-Zero house using a more off the shelf plan/approach?

It's a long way from an earthship to a 2014 Net-Zero house. Why don't you start with Net-Zero, and then tinker and have fun from that design starting point?

If money is an issue, why not build a 'Pretty Good House', and add the solar later? And cost of ownership would be lower than what you are trying to design anyway?

A pretty good house is all I aim for in the end, just learned about net zero the other night, and that was pretty much the plan all along, did not take much to realise a true Earthship tires and all won't do to well in Michigan, I really like what I read about passivhaus, if the building is well insulated solar gain might just do the trick entirely and than some. as for money granted I could take a construction loan like everybody else and order suff out of a catalog that would much defy the point this is going to be an ongoing process I have some funds and I'll come across more as I go that is the plan here, at the moment I am only looking into the structure aspect, all those renewables can come later

Every building needs a properly done heat loss analysis to allow properly sizing the heating system. A passive solar building also needs a properly done heat gain analysis. There are many so called passive solar experts and architects that will tell you that your fenestration area needs to be 7-12% of your floor area and they will charge you a small fortune for this worthless advice or their plans. You really need to learn to run the BTU numbers yourself or you should consider hiring someone to do this for you. You will be very disappointed if you don't get this right.

Posted By sailawayrb on 30 Jan 2014 02:41 PM
Every building needs a properly done heat loss analysis to allow properly sizing the heating system. A passive solar building also needs a properly done heat gain analysis. There are many so called passive solar experts and architects that will tell you that your fenestration area needs to be 7-12% of your floor area and they will charge you a small fortune for this worthless advice or their plans. You really need to learn to run the BTU numbers yourself or you should consider hiring someone to do this for you. You will be very disappointed if you don't get this right.

got it, I read about some of those rules of thumbs on your site, part of the reason I am holding of on hireing any "expert" and trusting my project to a rule of thumb, I have done some readings into it, the more I come across the more obvious it is that a tire house on top of plain dirt was a bad idea for my area, I like what I read about the passivhaus, minimizing the need should be a priority, just like electricity, you first reduce the load than look into pv

That’s the right perspective…first reduce your needs BEFORE you design what is needed… Way too many people get obsessive about maximizing insulation R-value and using expensive fenestration to minimize U-factor and associated heat loss. The first step should be to minimize the building size and the amount of fenestration that you really need. 800 SF per person isn’t really a shack, but few folks these days would be happy with this size. High SF/person combined with large family size is not really green sustainable living no matter how well insulated and energy efficient you make the building…which I tend to view more as self-delusion to avoid looking in the mirror and seeing gluttony.

my drawing is basicaly 6 rooms 11x11 which is 726 sqft,counting kitchen and bath liv and 3 beds, I am not counting the closets or the buffer to the south, that will add up to another 726+121sqft, the actuall livingspace/heated/cooled is 726sqft, and that is for 3 people, 2 adults 1 kid, and an extra bedroom for when grandma might be visiting, and I find it plenty at say not even 200sqft/person, there was a thread on here I read, looking for inspiration, I did not want to say it but it should be banned, builder was looking for an eco solution for some issue on this house that was 1700sqft on the first floor another 1000 on the second some 600 worth of basement 5 bedrooms 3 1/2 bath for 2 adults, you get the idea, I stopped reading right there, whatever he was on to had nothing to do with what I am looking for not sure what he was trying to acomplish but something about some special venting system,,,,,,,
my bottom line is shelter, I do not need an overcomplicated stadium sized building, one should not get too confortable inside anyway there is a whole lot of stuff to do outside too, that is part of the reason I am not looking into the hydronic sistems you like so much, yet. I would like in the end to have as passive of a building as possible, as little systems as needed, part of the reason why I am looking into what has been done with Passivhause to reduce the demand even more, same mentality having the closet space surround the living space, more buffers, same reasoning for the south buffer ( got into it quite a bit with a couple felow on priuschat forum ), the idea is that if done well it wont need a lot of energy to be brought up to 70F+ whatever the code requires, and honestly 70 is fine when outside is -20, hopefully just watching tv at night will warm up the room mine is always on any how ( bad boy )

at the moment I am kindof stuck arround the fenestration, just trying to catch up and get familiar with some of the principals but supposedly if done wrong might loose more heat that it would allow through

Posted By georgec on 30 Jan 2014 10:23 PM
 the actuall livingspace/heated/cooled is 726sqft, and that is for 3 people, 2 adults 1 kid,

726 ft² for 6 people? You might want to rethink that and I have a feeling your County building code department will have a red flag issue with that. Don't turn building a home into a morality issue. Build what will make you live comfortably and what you can afford.

I think you miss-counted Lbear, I get 3 people in 726 SF. I suspect many folks these days would find this way too small. However, 50 years ago this would be about average. Of course 50 years ago, we were also a better country going in a better direction too.

The best fenestration is far worse than the worst ceiling/wall with regard to heat loss, so you have decide how much energy efficiency you want to throw away to have a view of the outside. As you say, it might actually be preferable to be outside than to be able to look outside. So you are back to making a decision about what you think you want (which can often be biased by what you see others do) versus what you actually need… Save some money to travel the world and have a meaningful and rich life. Once you experience the high quality of life that people in other countries have while living in small buildings, you will fully appreciate how obscene our construction practices have truly become.

Posted By Lbear on 30 Jan 2014 11:41 PM

Posted By georgec on 30 Jan 2014 10:23 PM
 the actuall livingspace/heated/cooled is 726sqft, and that is for 3 people, 2 adults 1 kid,

726 ft² for 6 people?

Has anyone ever told you that your reading comprehension sucks?

Posted By arkie6 on 31 Jan 2014 09:47 PM


Has anyone ever told you that your reading comprehension sucks?

I was responding on my phone and this website does not have a smartphone default site so the website comes in microscopic on a phone. It was my error, I'm sorry, but no need to get all hostile and start personal attacks.

yeah and I tend to write the same thing twice just to get a point across in this case more detail, me the wife and a 4 year old, and we still have a spare bedroom for when grandma visits, yet look at the plans ( scribble ) it's plenty, I could have spaced the poles at 14 feet but that gets into 3x14 girders etc.... I may still do the 3x14, the plan was all along to buy or make a sawmill ( im good at that ) so lumber cost don't concern me much the mill does.

still since you brought it up the code requires 2 ocupants max /bedroom and I have 3 bedrooms in the plan, 2 adults 4 children is not outrageous, you and the rest of the country may think so, but in the end the house is just to throw your stuff ( well some of it at least ) in and rest your head at night, there is no call for 3 1/2 baths for two adults unless it takes longer for your stink to go away than it takes you to dump another, speaking of which that project was talking about an HEV drawing out of the baths ( great idea ), a movie hall a basement for a shark pool, you get the idea, there is a whole nother world outdoors too, my current house is 800 sqft, had my parents crash over for a few months the other granma for 6 months ( not at the same time ) but even now my boy has yet to spend a night alone, for the most part he took my spot and I crash on the couch reading this kind of stuff, I never spent a night alone in the house to this day, I was 21 when it almoast happened and couple hours into it I called a buddy over and he crashed for the week, and honestly how much time do you spend in the house anyhow I'm always bussy making bills,

to each is their own I guess but even the wife said any bigger of a house she may need to hire help cleaning it, how how much of a lifetime should one devote to housing, I may have mentioned this but the house I grew up in grandma built while grandpa was in the army and she lived in it all her life mortgage free raised 3 children and 7 grand children, we all grew up in one large room with two large beds, but we did not go inside till we were dead tired and as soon as the sun came up we were back at doing something else stupid, honestly I never once felt crowded, too bussy chasing eachother.

just a different lifestile and honestly grandma only went to shool first grade knew how to read and count change, and for some reason I live in a house somebody else built, that in itself is motivation enough for me to do something in this lifetime.

George

oh I forgot I do have 2 large dogs, each bigger than the wife, they don't like it inside much either just the winter nights they apreciate it, while some would consider them in the plan it did not even dawn on me, yet they are family too, and permanent ocupants, but no I'm not adding a room for each, bit sarcastic here, three months out of the year they can crash on the kitchen floor at night, they are too bussy most of the time hunting critters and scaring the meter man,

Posted By sailawayrb on 31 Jan 2014 12:43 AM
The best fenestration is far worse than the worst ceiling/wall with regard to heat loss, so you have decide how much energy efficiency you want to throw away to have a view of the outside.

since you know your stuff maybe you can settle this, got into some heated disscussion on another forum, bottom line per sqft wht is best cheap double pane or fancy expensive tripples, that it for vertical orientation, south facing. granted when you count the insulation only we figured a fictive R 10 for the best tripple pane money can buy, R 2 for your average free recycled window, hands down fancy glass, than we figured gain, zipcode 48174 DTW weather station, couple fancy websites with fancy softwares, sun trigonometry etc, turns out overall per year, winter or day the extra 0.15%shgc from the third glass cuts the gain more than it saves energy. even in Michigan, even in the winter even at a 40F difference, 3 hours of sunlight wersus 24 hours of pour insulation. well you/re the expert, spend the money? ( I PROBABLY WONT ANYHOW ) added weight, sturdier frame needed and overall less gain that beeing said if the glass has a net gain it's better than any wall or ceiling with super insulation, or so it would apear to me, only for a shaded northern window where gain is close to zero, I would agree with you, again I am not considering any of those, regardless of the street view, they can stare at my backside blunt wall from the street for all I care

George, you are indeed correct that fenestration can produce a net heat gain or a net heat loss. My previous comment was only with regard to the fenestration heat loss. For passive solar buildings where you also want to maximize the building energy efficiency, you place the required area solar gain fenestration to meet your heating design objectives on your wall facing the equator and you minimize the fenestration on all the other walls. Zero fenestration on these other walls would certainly be minimum and optimum for energy efficiency.

To determine the specific answer to your question George, you really need to run the BTU numbers for your specific building design and the specific location where you are constructing your building. Let’s use the example that is in the instructions for our free DIY passive solar design software. This example is a building constructed in Rogue River, OR that has a latitude of 42.44 degrees and a wall facing due south where 232 square feet of 0.60 SHGC fenestration is placed. In January, the historical climatic sunshine for Rogue River is 32.26%. The software tells us that 249,091 BTU/Day of fenestration heat gain will occur during clear sky conditions in January. Clear sky conditions may only occur a couple days in January, so while we must design our passive solar building to be able to handle this blast of clear sky heat gain without cooking our building inhabitants, we don’t have any false illusions about receiving this clear sky heat gain value every day in January and we certainly don’t use this clear sky heat gain value for planning our supplemental heating requirements…unless we deviate from “pure” passive solar by also integrating a hydronic radiant heating system into the design which allows us to move and use all this excess heat gain. So the software “derates” this clear sky heat gain to 80,357 BTU/Day to account for the expected climatic sunshine in January. We use this climatic heat gain value for planning our supplemental heating needs and to allow comparison to our expected fenestration heat loss to determine how much merit this passive solar building design has in this location.

In January, the mean daily temp is 46.2 degrees F in Rogue River. If our design indoor temp is 70 degrees F and our fenestration has an U-factor of 0.45 (i.e., R-value of 2.2), our fenestration will have a heat loss of 2485 BTU/Hour or 59,640 BTU/Day. So even this relatively poor fenestration that does not use any insulated shades at night to reduce night time heat loss still produces a net heat gain of 20,717 BTU/Day. If you use fenestration having a significantly lower U-factor (i.e., having a significantly higher R-value), the net daily heat gain will be significantly higher. If you live in location that receives less sunshine and perhaps also has a colder climate too, the result may indeed be a net heat loss even if you use significantly lower U-factor fenestration and use insulated shades at night.

So there is no one answer to your question George. Anyone who tells you that there is one answer is smoking dope, and not the kind that has become legal in WA. So you really need to run the BTU numbers for your specific building design and for the specific location where you are constructing your building.

I agree 100% Lbear, it is one thing to debate a subject with passion and quite another to just be a hostile bully making those kind of ignorant and unproductive personal attacks. I think some folks think that a high post count somehow makes them more of an expert than others. Research data has shown just the opposite to be true. Each post and debate stands on its own merit. We should all do our best to police this forum, call out offenders when needed, and ultimately drive out repeat offenders.