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New house, wall design

Post in 'DIY and General non-hearth advice' started by jklingel, Oct 29, 2007.

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  1. jklingel

    jklingel Feeling the Heat

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    I am looking for other insulation freaks! I am building a new house, and have an idea of how to insulate the walls; I need opinions from anyone w/ experience doing such. The house will be one story, over a full basement (probably not a day-light basement). My plan is to have a double wall, the outer one being either 2x4 or 2x6. The outer wall will be filled w/ fiberglass batts, which I hate w/ a passion, but they insulate real well. The inner wall will be 2x4, and will be left empty for wires/pipes. The space in between the two walls (either 6" or 8") will be filled w/ R-Tech insul boards. On the outside of the inner wall will be the normal visqueen VB. My plan is to build both walls and VB the inner one. Then, I'll stack one layer of R-Tech boards horizontally, then another layer vertically (to cover cracks between sheets), assuming I can get 3" thick boards. If not, then I'll have three, 2" walls, or 4. R-tech will be loosely nailed to the 2x4's, then successive layers will be glued to each other on the face and edges. The lid will be 10" glass batts w/ blown cellulose over that, to fill any voids, etc. BTW: My present house, which I built in 1980, is a double wall, both 2x4 and filled w/ fiberglass, and I have 6" fiberglass batts in the space between the walls. Sooooo.... does anyone see any problems? Sounds pretty simple to me. Thanks. john

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  2. KeithO

    KeithO Minister of Fire

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    John

    Have you considered Structural Insulated Panels ? Try this website for technical information http://www.sips.org/content/technical/index.cfm?pageId=159

    Since you are in Alaska and logistics could potentially be a significant issue, I would check availability and local resellers. If not, there is nothing stopping you from making your own SIP panels. You need a flat surface to work from and to clamp the 2 OSB panels to the core foam for bonding, one can use vacuum bagging, like they use in composite construction. The advantages are that these systems have some of the highest R values available, do not have bridges by having sticks every 16-24 inches, are easier and quicker to handle, thus on site work is faster and the finished home is generally tighter than an equivalent stick home.

    The factory built home kits http://www.valubuild.com/kits.htm have some nice features including wiring chases already provided in the walls etc. If I went with that system, I would use the same stuff in the floor and on the roof to get the best possible insulation in a compact package. I'm planning to move to Colorado though, to make good use of the sun, so I need a home with thermal mass = 12" concrete with external insulation on all external walls and floor and heavy masonry / concrete internal walls where there need to be any. Living space open plan with a masonry heater centrally located and the usual south facing greenhouse / extended roof overhang for blocking the summer sun. Different strokes for different folks....
  3. jklingel

    jklingel Feeling the Heat

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    No, I had not considered them, as I am not sure I've ever heard of them. Will check them out, though; interesting idea. Thanks.
  4. jklingel

    jklingel Feeling the Heat

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    Just checked them out. VERY interesting. Further research is warranted.
  5. Nofossil

    Nofossil Moderator Emeritus

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    If you do an energy loss budget, you'll find that doors and windows will account for virtually all of your loss long before you get the walls to the point that you're describing. I'd dedicate some of the space between the inner and outer walls to make sliding insulated 'pocket' doors that you can slide closed to cover doors and windows at night or when rooms are unoccupied and the sun is not shining in.

    I've seen some really nice ones - foil on the outside, tapestry fabric on the inside, foam core with wood outer frame. If they're really easy to use, you will be more likely to use them.
  6. WILDSOURDOUGH

    WILDSOURDOUGH New Member

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    Started building our SIP panel wall home last spring-2006. It is a AmeriPanel kit that was customzed. Build it on an ICF (Insulated Concrete Form) foundation. Ranch style, 36x65 with an attached 3 car garage, put half log siding on it- It looks just like a Log home, except that it's super insulated and we were able to put it up (wife and I)ourselfs (big-big cost savings). Lived in the basement last winter (Radient heat in the concrete floor)- Finished up outside and sheetrock up inside (upstairs) this year- should be able to move upstairs by christmas- sweet !
    If you are looking to build a modern, energy-efficent home- take a hard look at SIPs and ICF- you can do any style with them.
  7. jklingel

    jklingel Feeling the Heat

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    If you do an energy loss budget, you’ll find that doors and windows will account for virtually all of your loss... •• ROGER THAT. THE R ON A WINDOW, EVEN THESE NEW GAS-FILLED, MAKE ME SICK. I HAVE SMALL WINDOWS, BUT THE BOSS WANTS LARGER ONES IN THE NEW PLACE. THESE POCKET DOOR COVERS ARE VERY INTERESTING; WILL CHECK INTO THEM. GREAT IDEA. THANKS.

    [quote author="Wildsourdough" date=""]Started building our SIP panel wall home last spring-2006. It is a AmeriPanel kit that was customzed. Build it on an ICF (Insulated Concrete Form) foundation. Ranch style, 36x65 with an attached 3 car garage, put half log siding on it- •• WILD: THAT IS QUITE INTRIGUING. I WILL HAVE TO LOOK AT THAT PRETTY HARD. HOW DO BANKS FEEL ABOUT THESE? (LOOKING DOWN THE ROAD SO THE NEXT FOLKS CAN FINANCE....) AS FOR THE FOAM BLOCKS IN THE BASEMENT, BEEN THERE, DONE THAT, AND NO THANKS (IF YOU ARE TALKING ARXX BLOCKS. FOAM, FILL W/ CONCRETE, BLOW OUT WALLS, ETC). PAIN IN THE ARSE. I WILL GO W/ ALL-WEATHER WOOD; NOT A LOT OF HEAT LOSS OUT OF A BASEMENT ANYWAY. DO YOU HAVE ANY PROBLEM PM'ING ME YOUR FLOOR LAYOUT? I WOULD LIKE TO SEE IT FOR IDEAS. WE HAVE LOOKED AT 100 OTHERS, BUT MY SWEET-CHEEKS DOES NOT LIKE ANY YET.

    GREAT IDEAS ON THIS FORUM!
  8. sgcsalsero

    sgcsalsero Feeling the Heat

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    I have mentioned this book before and will continue (thanks Rohnemas) . .Insulate and Weatherize by Bruce Harley . . it gives a priority order of things to consider, doors and windows are not in the top three If I recall, it was a real eye opener
  9. jklingel

    jklingel Feeling the Heat

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    On a (perhaps) final note on this thread: I ran some more designs last night on my heat loss and cost SS, and found that I can add 40% to the R-value of a "standard" wall (2x6, 2" of Extr Polysty on the outside) and only 10% to the cost if I use a double wall as follows: 2x6 outer wall, stack 5.5" glass batts together, then an inner 2x4 wall, left empty. This is very similar to my present house. I had hoped that using EPSty board instead of the 5.5" of fiberglass would be the ticket, but it is way to spendy for this purpose. Yes, the wall labor increases at least x2 for building the second wall, but I look at it as "hobby time", in a twisted-mind kind of way, and it does not add appreciably to the time of building a house. So, I guess it will be more of that itchy crap that will get installed. Oh, sigh....
  10. kenora

    kenora Member

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    I don't know if you have considered using ROXUL insulation instead of fiberglass pink (I hate that stuff). The Roxul is easier to cut, doesn't burn or melt and is way more dense so it doesn't allow convection currents to occur inside the insulated cavity. I read that at -40 these currents reduce the "effective" R value of fiberglass to about R20 since the warmer air (next to the ceiling) can migrate upwards to the cold air in the attic. On a side note the Roxul has a better R value per inch as well. I have used it a lot lately and love it.
  11. tutu_sue

    tutu_sue New Member

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    The recommendation from eere.gov? is to caulk the each stud wall cavity where the stud meets the sheathing and the bottom plate to the subfloor. Basically caulk the whole house top to bottom anywhere two different materials meet before you put up insulation or drywall.
  12. precaud

    precaud Minister of Fire

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    For newer construction, that's probably true. For my old beast, not true...

    BTW, there are some interesting videos of Bruce Harley and others here:
    http://www.bestofbuildingscience.com/enclosure.html
  13. Rhone

    Rhone Minister of Fire

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    Updating...

    Okay, I had to update cause I never heard of R-Tech panels, and can't seem to find info on them. They do appear to at least be foam which, my post originally said you need foam hence, the update. Can you enlighten me about what R-Tech panels are, I'd like to know what they're made of (expanded or extruded polystyrene, or maybe polyisocyanurate) and how thick the foam?

    Honestly, you should think about where you live. Fiberglass the bigger the temperature difference the worse its effective R-Value. Also, the more air movement in fiberglass the worse it acts, and just a 1% gap can have it lose 25-50% of it's R-Value. You live in a 14,000 Heating Degree area, that's even worse than the research base on top of Mt. Washington, even those living in Minnisota and Michigan which are at the top of the cold charts in the continental USA top off at a little over 8,000. I would not use fiberglass where you are, in the exact conditions it works at its worst.

    Why not 2x4 walls with 4" of extruded polystyrene foam on the outside. You'll have a complete covering of foam, no short circuiting, and 4" of foam will insulate better than 30" of fiberglass where you live (that may be sarcastic but you get the point). You need to focus on foam board insulation, and having a choice of doing 4" of foam, or 2" of foam and R13 or R21 batts the 4" foam will insulate better. You can also overlap them preventing gaps, and any small spaces can be filled with expanding foam or caulked.

    I have a heat loss analyses calculator that uses the heating degree days of where you live. Plugging in Fairbanks, Alaska if you build a house with 4" of XPS foam on the outside, and leave it at that you should go through 0.89 cords for every 1,000 sq ft of wall surface area/year (or to look at it another way 4" of foam will lose 16.8 million btu's/year per 1,000 sq ft). If your walls account for 1,000 sq ft that setup will only take less than a cord/year for your walls. Let's up it to 6" of foam, that reduces your heat loss to take only 0.59 cords/year to heat per 1,000 sq ft surface area (or 11.2 million btu's heat loss through walls/year). So, you have to figure out if paying for 2" more foam would be worth it, and again the above is for Fairbanks Alaska.

    So, you want to minimize on what's called short circuiting and maximize the amount of foam board insulation & air sealing I'd opt for just 2x4 walls with 4" of foam insulation on the outside (or if you want put 6") and with the $ saved work on perhaps something that can cover the windows at night. With probably the $ saved you can make your own shutters out of excess foam board that you can close at night and add R10 to the windows that go against seals. Also, spend more on air sealing as even a pinhole leak in that house with that temperatue difference is going to cause a huge amount of heat loss. Otherwise I think a fiberglass outside wall, then an R-Tech wall between, then a regular open wall is a lot of wall and $ and I don't expect will be as good as just putting foam on the outside of a single wall and air sealing. The only problem I have, is that I'm not a fan of hollow walls period. Any leak in the bottom and top is like a tiny chimney that causes huge amounts of heat loss. I'd spray wet blown cellulose on the inside walls, all of them to minimizes air leaks/movement better, has better consistent R-Value, and adheres in place and not have hollow walls. It's not too difficult to do work with cellulose in the walls, electricians and plumbers have to work through it all the time. For air leaks, most important place to seal them is the attic, followed by the basement, followed by the main floor because of what's called the stack effect. For windows that you want to open, you may want to pay the extra for casements which are better at air sealing than double-hung (but cost more). Casements close on a thick rubber compression seals, double-hung use 1/8" bristles for air sealing that the windows slide up/down. Where you live, you don't want to depend on bristles IMHO.
  14. fishboat

    fishboat Member

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    Seems to me that the insulation with the best chance of sealing out leaks would be the spray-in / expanding foam variety, particularly when you're talking about harder to insulate areas like around windows & doors. They use it on This Old House on a regular basis. Do a search on their website I'm sure you'll find it.
  15. precaud

    precaud Minister of Fire

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    Good advice from Rhonemas...
  16. jklingel

    jklingel Feeling the Heat

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    BEEN OUT OF STATE FOR A BIT, HENCE A DELAYED REACTION. IN CAPS... HERE WE GO...
    [quote author="Rhonemas" date="1196885785"]Updating...

    Okay, I had to update cause I never heard of R-Tech panels...R-TECH IS WHITE, AND IS MORE OF A BEAD-BOARD THAN ESP. NOT REAL TOUGH, AND 4.1 R-VALUE/INCH, AND CHEAPER THAN EPS. FOR WHATEVER REASON, IT IS WHAT EVERYONE USES ON THE OUTSIDE OF HOUSES.

    Fiberglass the bigger the temperature difference the worse its effective R-Value. Also, the more air movement in fiberglass the worse it acts, and just a 1% gap can have it lose 25-50% of it's R-Value. NEVER HEARD OF THIS ABOUT FBRGLASS. INTERESTING. WITH A GOOD VAPOR BARRIER AND TYVEK AROUND THE OUTSIDE OF THE HOUSE, I HAD NOT CONSIDERED AIR ZIPPING THROUGH THE FBRGLASS MUCH; NOR HAS ANYONE ELSE THAT I AM AWARE OF. MAYBE I BETTER LOOK INTO THAT MORE. CARP. FOR LEAKS, THE ONE REASON I LIKE FBRGLASS OVER FOAM (IN UGLY PLACES) IS THAT IT "FITS" IRREGULAR PLACES BETTER.

    You live in a 14,000 Heating Degree area, that's even worse than the research base on top of Mt. Washington, even those living in Minnisota and Michigan which are at the top of the cold charts in the continental USA top off at a little over 8,000. I KNOW. AND I CHOSE TO LIVE THERE.... SOMETIMES I WONDER.....

    Why not 2x4 walls with 4" of extruded polystyrene foam on the outside. I THINK I WILL NEED AT LEAST 2X6 FOR LOADS.

    You'll have a complete covering of foam, no short circuiting, and 4" of foam will insulate better than 30" of fiberglass where you live (that may be sarcastic but you get the point). ROGER THAT. THE BEST FOAM (EPS) HAS AN R OF 5/INCH, BUT IT IS REALLY SPENDY, TOO. ON MY SS, IT WILL BE REALLY TOUGH TO PAY FOR A HEAVILY FOAMED WALL WHEREAS A HEAVILY FBRGLASSED WALL WILL COST ESSENTIALLY THE SAME AS A 2X6 FBRGLASS W/ 2" EPS OVER IT. THAT ASSUMES THE THE FBRGLASS REALLY INSULATES AS THE BOOK SAYS IT DOES, WHICH IT APPARENTLY MAY NOT. HMMM.

    You need to focus on foam board insulation, and having a choice of doing 4" of foam, or 2" of foam and R13 or R21 batts the 4" foam will insulate better. You can also overlap them preventing gaps, and any small spaces can be filled with expanding foam or caulked.

    I have a heat loss analyses calculator that uses the heating degree days of where you live. THANKS! I'LL COMPARE YOUR NUMBERS WITH MY SS, JUST FOR KICKS.

    So, you want to minimize on what's called short circuiting and maximize the amount of foam board insulation & air sealing I'd opt for just 2x4 walls with 4" of foam insulation on the outside (or if you want put 6")... IF YOU ARE INTERESTED, I WILL SHARE W/ YOU THE COST OF A HEAVY FOAM WALL W/ THAT OF A HEAVY FBRGLASS WALL. BOARD IS THOUSANDS MORE (WHOLE HOUSE) WHICH TAKES A LONG TIME TO PAY BACK.

    Also, spend more on air sealing... THIS IS EXACTLY WHY I WAS THINKING OF AN EMPTY 2X4 WALL. SINCE THE VAP BARRIER WOULD BE ON THE OUTSIDE OF IT, I WOULD NOT HAVE A HOLE(S) ARE EVERY ELECTRICAL BOX ON AN EXTERIOR WALL. YES, AIR BILL BOP AROUND IN THERE, BUT IT WON'T GO ANYWHERE, SO I WAS NOT WORRIED ABOUT HEAT LOSS THAT WAY. BESIDES, IF I DO SEAL IT WELL, THEN I GET A LITTLE BIT OF R VALUE OUT OF IT, AND NO HOLES.

    Otherwise I think a fiberglass outside wall, then an R-Tech wall between, then a regular open wall is a lot of wall and $ and I don't expect will be as good as just putting foam on the outside of a single wall and air sealing. THOSE WERE MY THOUGHTS UNTIL I RAN THE NUMBERS. THE 2X4s ARE CHEAP. SEE ABOVE COMMENT.

    The only problem I have, is that I'm not a fan of hollow walls period. NOT LEAKY ONES, FOR SURE.

    For windows that you want to open, you may want to pay the extra for casements I THINK THAT IS ALL THEY SELL HERE. AT LEAST THAT IS ALL I AM EVER PRICING.
    I'LL HAVE TO FIND OUT WHAT ROXUL (OR WHATEVER WAS MENTIONED ABOVE) IS; NEVER HEARD OF IT. THANKS ALL FOR THE INFORMATION. MUCH TO DIGEST/LEARN ABOUT. JOHN
  17. kenora

    kenora Member

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  18. jklingel

    jklingel Feeling the Heat

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    Ken: Thanks for the link. I downloaded a bunch of Roxul lit. Basic ????: Is this fairly easy to fit and form, like fbrglass, or pretty rigid like foam board? It looks sort of soft and flexible in the pics.... sort of. How spendy is it compared to fbrglass, etc? This may well be a substitute for fbrglass batts and/or the R-tech. BTW: Someone mentioned spraying in foam: Good idea. I will call a spray outfit today and see what the skinny is on perhaps spraying the whole damn cavity full, say 10-12" and be done w/ it. That ought to give about as tight a seal as anything else, and if it does pull away from the studs a skosh, which I've heard it can do, it won't matter because there will be a continuous layer between the outer studs and the inner wall. I have seen a few foam/wire mesh igloos up here, but never checked into whether or not they last, etc. They never really caught on, and I don't know if that is because of thermal issues or the house shape. Man, the more I learn the less I know.... j
  19. fbelec

    fbelec Minister of Fire

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    i don't know if we are talking the same thing rhonemas but i have a good friend that had a company come in and spray foam his attic. it might have been the same name you said but not sure. it's open cell insulation so he did not need to do proper vents. this stuff is amazing. on the day i went over to visit it was a mid 90's and humid day full sunshine. he has a 100 year old house. his attic would normally been hot enough to fry a egg on any metal surface. when i went up there in mid afternoon the thermometer said 78 degrees. i'm not sure if it is the same stuff but what a difference. this stuff dries in minutes so you have to tell them that you'll be installing wall board so that they scrap off the excess right away
    it cost him between 2 and 3 times what a company would charge to do rolls of fiberglass but after seeing that it will pay off in no time.
  20. fbelec

    fbelec Minister of Fire

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    i'll call him for the name
  21. kenora

    kenora Member

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    around here its about 10% more than fiberglass (but it has 10% better R value as well R22 for 2 x 6 stud wall vs R20)...I'd pay 100% more cause I hate fiberglass...The Roxul its easy to cut, it's soft and quite firm and heavy. I used it to insulate behind a gas fireplace I installed a few weeks ago, the chase had been sealed years ago and had to be finished with insulation, vapor barrier and drywall before we could install the f/p. It was nice not to be itching and scratching and worried about breathing that fiberglass crap. And one of the things I really like is that it sound proofs WAAAAAAAAAAAAAAAAAY better than fiberglass. A friend used it for a basement bedroom, he insulated the walls of the bedroom (surrounded on 3 sides by a bathroom, laundry and family room) so he could sleep during the day. The noise decrease was amazing to say the least. I had done the same years ago with fiberglass and it was a waste of time.
  22. jklingel

    jklingel Feeling the Heat

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    I just found out that neither Ho Depo nor Lowe's in Frb carry Roxul. I'll try Anchorage, then it may be a big shipment from Canada.... or a drive down there to fill a trailer.... This stuff is beginning to sound REAL good. j
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