In Alex Wilson’s comments in the new FHB Green Building blog he says go for R-40 walls and R-60 roof. I’ve been looking at SIPs and ICFs as 2 ways to build the house we want and it looks like getting this level of insulation is going to be hard to do. What is the recommended best way to achieve this kind of insulation?
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Double wall framing with dense-pak cellulose, or Larson trusses which are two 2x2's separated by a segmented web.
Not knowing where you live the best "bang for the buck" has a lot of variables.
Check with your local cooperative extension service, ours has a guest speaker in our case a professor from the University of Alaska Fairbanks that comes down here to Anchorage two or three times a year putting on free seminars on cold climate construction.
In our location a passive solar home makes a lot of sense, especially since in today's paper lead headlines is the local (natural) gas company is planning on raising their rates 25% this fall.
There are a number of ways to build today, again depending on where you are located (and how deep your pockets are) , straw bale, ICF, SIP, Larson Truss, Mooney wall to name most that I know of. All will give you a great home.
Iam not fond of fiberglass insulation for a modern home, it will not work well unless it is in a sealed cavity and that is difficult to maintain in a stick built home. Spray in foam either open cell or closed cell is far more efficient and there are pros and cons to those as well.
I am partial to ICF because of several reasons. I can erect the walls and place the steel and have it ready for the roof in a matter of a few weeks after the slab is in place. I am in an earthquake zone and it makes for very strong walls, quiet, easy to heat as well. Remember you will need to have a HRV or HVAC and be sure that they are engineered for you building. Oversizing (your heat system) is a larger problem than under-sizing in a super-insulated home.
Here I will be building a "frost protected shallow foundation" a super-insulated slab on grade with external underground insulation around the foot print of the slab. My soil in the area where I plan to build my next home has a high enough water table that precludes that ability to have a basement. What ever you do depending on your soil temperature (anywhere but the southwest) I would strongly suggest you insulate (well) below your slab regardless if it is on grade or below grade ie basement.
Pre plum for solar hot water and PV even if you don't think you will add it as you build. There is a lot of rebates that are out there and may make it cheap either as you build or later on. Far cheaper to have it pre plumbed and add it later vs. trying to retro it after the home is built.
Go to Greenbuilding.com loads of info there also.
Hope this was not too much info. Good luck, you have came to the right spot.
Getting high insulation values is not as hard as you might imagine and the Larsen system is a fine way, as are SIPS and ICFs.
Super insulation is fast becoming a buzzz word for high r-values but it is only one component in your homes total building envelope. That's not to say that insulation isn't important, it is, very.
Any opening (door, window, skylight) in the structure's exterior envelope must be considered as well. Infiltration is the obvious reason here. But....there is the matter of the interior comfort levels....as in ventilation (air changes), exhaust, heating and air conditioning.
Since I just finished a "high energy efficiency" commercial building, factory, that qualifies for Federal Tax reduction credits I have accumulated a few sites for you to check out. You can search through these and get some great ideas and directions for what you intend to build. ('Talisker' was correct in that the minimum recommended r-values are R-40 and R-60 up in the Alaskan area, but the same chart also addresses the values in the floor systems). Seems there are a lot of info sources.
http://www.ornl.gov/sci/roofs+walls/insulation/ins_08.html
http://www.simplyinsulate.com/savings/index.html
http://www.energytaxincentives.org/consumers/insulation_etc.php
http://www.sips.org/
I'd take a look in the FHB archives for even more ideas.
Keep us posted. ciao, ted
Thanks for everyone's input so far. The house will be in Michigan's Upper Peninsula on the edge between "cold" and "very cold" climates on the map. I plan on triple glazed windows with good draft sealing, and HRV and a well insulated slab. I'm thinking of doing radiant floor heat with an electric tankless water heater as most of the heat will be from burning wood (masonry heater with outside combustion air intake). It will be south facing with windows to take advantage of passive solar but it is on a wooded lot with evergreens and a ridge to the east that will both limit our solar collection ability.I'm partial to SIPS and my wife likes ICFs. I know either will give me a tight house more easily than some other methods so we are planning on one of these two methods for building. But let me rephrase my question: the ICFs I've seen are rated at about R-26 and SIP manufacturers and dealers I've talked to suggest a 6 inch SIP wall which has about the same R value as the ICFs in the mid 20's. So what does one do to get the R value up closer to Alex's ideal R-40?
Research SPI's on the FHB site. I saw past articles about the different insulation materials some manufacturers use. As I remember some 6" SIPs using a better insulation get about an R36.
Ine, building with a SIP system will get you a tight house but, unfortunately, I don't know of a way that the ideal of R-40 is achieveable using just those panels. And that doesn't mean that they are not available, I just have not seen them. And unless a manufacturer could produce a "custom" panel that gets that rating you may have to consider adding layers of insulation over the panel system.
I mentioned the factory/office building I designed. The exterior walls around the office area were layered. The facing material was an aluminum composite panel (the Owner manufactures these) over two layers of 15#felt, over an isocyc. panel (5 1/2" thick, rated at R-25)attached to a 12" concrete block(foam filled. R-3), with 2x4 studs @24"o/c (high density fiberglass insulation, R-19) and 5/8" fire rated drywall. Whew! The Owner's budget was not busted by this but it wasn't something that most folks would find on or part of a home.
It seems self-defeating to add an interior wall system over the SIP but since it would not be load bearing the installation would be straightforward enough and you could get an additional R-19.
The problem I have is that now you have a 10" plus/minus thick wall which presents its own challenges at openings and we are back to stick built, to a degree.
One of the things I find challenging is developing solutions to residential situations using commercial applications. Let me give it some thought, perhaps the isocyc panels could work, they are actually designed as roof insulation and quite expensive.
ciao, ted "You can have it fast, good or cheap. You can only have two of the three. Fast and good, it won't be cheap. Good and cheap, it won't be fast. Fast and cheap, it won't be good. Now, what's your choice?"
Turk, the rating systems leave a lot to be desired. With ICF the formula is (in my opinion) is not exactly revelent as x amount of ICF to y amount of "R" factor. This is due of course to the sealed wall with little loss(around windows and doors depending o the type of "bucks" used). There are cold conducting headers and joints found in the SIPS, granted they only comprise a fraction of the wall but there is loss there. The testing institutes do not or can not in my opinion rate ICF's correctly. From what I have seen and studied ICF can not be beat for providing a superinsulated home.
I do think that the other methods mentioned in my earlier post can give nearly the same degree of insulation but they all take a great deal more time to construct and seal with of course the SIPs being the exception.
BTW I would not bash SIP's, they are a great product. In my location they are cost prohibitive because they are not made up here and to cost to have them shipped up is extremely high. I would like to have a sip roof on my ICF home but can't for the aforementioned reason.
In my opinon go with ICF walls and a Sip roof and you will be in good shape.
"In my opinon go with ICF walls and a Sip roof and you will be in good shape."
I agree. This discussion made me think about, and find, a couple of articles in "ICF Builder" magazine. One went to your point about the value of R ratings and the other to the initial point of this thread, namely ICF and SIP construction.
I would offer that both articles address, quite clearly, some of the concerns of integrating their systems.
Run over to http://www.icfmag.com/back_issues/apr-may_08.html#04 and look up
ICFs and SIPs, Completing the Envelope.Performance R-Value: Side by Side Comparisons
Found others in there also of great help, some resources too.
ciao, ted "You can have it fast, good or cheap. You can only have two of the three. Fast and good, it won't be cheap. Good and cheap, it won't be fast. Fast and cheap, it won't be good. Now, what's your choice?"