Best way to insulate our cabin

Discussion in 'Homesteading Questions' started by sancraft, Oct 9, 2005.

  1. sancraft

    sancraft Well-Known Member

    Messages:
    5,961
    Joined:
    Jun 7, 2002
    Location:
    Georgia
    I see the thick, pink fibergalss stuff and the thin silver stuff. Which is best? The cabin is 12x30 shell. We need to insulate and put up walls. Also, the ceiling is open rafters. What do we do about insulating there? THe sleeping lofts are right under the eaves. Do we need to add drywall or bead board to the ceiling too?
     
  2. Fire-Man

    Fire-Man Well-Known Member Supporter

    Messages:
    5,487
    Joined:
    Apr 29, 2005
    Location:
    South Carolina
    The pink stuff between the rafters and studs, use the one that best fits between your studs etc and the thickness of your studs and rafters---you never want the insulation mashed/compressed, the silver stuff on the outside nailed to your studs before the siding. Randy
     

  3. ihedrick

    ihedrick Can't stop thinkin'

    Messages:
    1,267
    Joined:
    May 15, 2005
    Location:
    Virginia
    I can't keep it straight, but also consider the R rating on insulation. I think the higher number is better...if I'm wrong I'm sure someone will quickly set me straight. I have to insulate my place too, and have been trying to get "learned up" on it before I start this do it yer self project.
     
  4. Cosmic

    Cosmic Well-Known Member

    Messages:
    596
    Joined:
    Jan 19, 2005
    Location:
    Ohio
    Lots of ways to do it.

    Personally I don't like the fiberglass stuff. Too expensive and if it gets wet has problems, can also get mold in it. It never fits exactly right, always some gaps. It is fast and fairly easy but I would not use it in my own house.

    One way is to use a good vacuum, like a big Wet / Dry vacuum, take out the filter and blow your own cellulose or rock wool insulation. Some places like Home Depot or Lowes have the machines to blow it in, maybe free use if you buy the insulation from them. Check with the Customer Service people, usually they have a list that you put your name on.

    To use your own vac, you dump it into something like a garbage can, break up the bale, fluff it up a bit and suck it up with a vacuum hose, put a hose on the discharge side and use that to get it into the walls.

    Another trick I like a lot is first put up some layers of cardboard over the studs before installing the drywall. Then can blow in the insulation, leave a good gap at the top, makes it easy to check you have a good fill. Must plan for the thickness of the cardboard when doing the electrical boxes.

    Or you can also pour in pearlite into the walls. Comes in bags. If you want the sleeping area to be within the insulated volume, then you don't insulate the ceiling overhead rafters, you go all the way up to the roof rafters. Or if you wanted maybe could do both. Whatever your druthers.

    For the overhead if using the roof rafters, you need to make an air vent system in the roof rafters if you are using the upper area and have no attic. Basically you build in a small gap, usually 3/4" to allow air to flow from the sofit area up to say a ridge vent or some other type vent. Lots of ways to do it. I like to staple the stuff called Reflectex over some wood strips. Has a very high temperature rating.

    Then you fill the remaining rafter depth with some type of insulation. Again, I like either peralite or blown in cellulose or wool. In that scheme can also use some more cardboard layers, usually also must finish with some type of structure cover like fiberboard, wallboard, etc.

    For R-Value the higher the number the better. It does not tell the complete story but is usually the measure used for most jobs.
     
  5. AngieM2

    AngieM2 Big Front Porch advocate

    Messages:
    44,854
    Joined:
    May 10, 2002
  6. comfortablynumb

    comfortablynumb Well-Known Member

    Messages:
    4,808
    Joined:
    Nov 18, 2003
    Location:
    Dysfunction Junction, SW PA
    get the highest R value you can afford, its worth it.
     
  7. dlangland

    dlangland dlangland

    Messages:
    827
    Joined:
    Jul 7, 2005
    Location:
    NW Iowa
    Is cardboard a wise thought...I tell you after burning cardboard boxes...yet over 2 months after I moved, in my back 40...I might beg to differ...Pure flame, and I am the queen of fire. Cardboard is one of the most combustibles of combustibles. Deb
     
  8. jeffreyc256

    jeffreyc256 Well-Known Member

    Messages:
    106
    Joined:
    Sep 24, 2005
    Location:
    Alabama
    If you do not have 2x6 exterior walls consider expanding them to 2x6 for more insulation. Use a building wrap under sny siding and also consider unsulation board under siding. Vinyl siding can also be supplied with additional coutoured insulation that also supports the siding and makes it stronger. Insulate the floor joists. IF the roof is not on now is the time to insulate for an open ceiliing joist system. Install 2x6 supports on top of the roof decking with 4-1/2 - 5 inch insulation board made especially for this. Leave 1/2 inch to 1 inch on top for air flow. Pay special attention to electrical and plumbing penetrations and window and door openings and empty spaces around them. Pay extra money now on insulation and design and save forever on the power bill and comfort.
     
  9. Cosmic

    Cosmic Well-Known Member

    Messages:
    596
    Joined:
    Jan 19, 2005
    Location:
    Ohio
    Cardboard in walls is not all that dangerous. Plus you are way overboard in using the electrical as the ignition source. I only use metal electrical boxes. If your electrical boxes are running that hot to ignite cardboard, you have many more problems than a fellow might want to handle. The Kraft paper on the fiberglass insulation will also burn. Cardboard and that paper have similar characterics. Should be fires all over the World.

    In this case the materials are inside walls not in free air. Many materials in homes will burn, many of them ignite quite easy. The most dangerous are probably out in the living spaces. One can always go to extremes and make anything happen. Workmanship also counts in building safe installations.

    Both cardboard and newspaper have been used for years. Many a miners shack had both. Cellulose normally used for blown in insulation is nothing but grounded up newspaper. If you are super concerned can just spray the cardboard with a little boron. Is what they add to the ground up newspaper. Makes a bit of fire retardant and helps with insects. If cardboard was as hazardous as you say, all the homeless folks would have all gone up in flames, they use open candles and cardboard, not to mention sterno, smoking and maybe the occasional blow torch.
     
  10. kabri

    kabri Almst livin the good life

    Messages:
    1,126
    Joined:
    May 14, 2002
    Location:
    W. Washington State
    We just finished insulating our cabin (12'x16 w/full loft). It has a gambriel (barn) pitch roof, so the soffits at floor level in the loft presented a challenge to create an airspace as mentioned above. We used non-formaldahyde fiberglass insulation in the walls on the lower level, and the rigid styrofoam sheets cut to size for the upstairs. Our framing is 2x4. We used 1" rigid sheets upstairs, and installed them flush with room side of the 2x4 studs, all the way to the peak beam. This leaves about 1" airspace between the plywood roof and the insulation. We also then covered the entire inside with a vapor barrier. Then, we installed cedar T&G panelling over that. Here's a pic, to illustrate since I'm not that handy with construction terms! [​IMG]
     
  11. Quint

    Quint Well-Known Member

    Messages:
    3,510
    Joined:
    Nov 12, 2004
    I was helping a neighbor with some plumbing at their new house which is under construction and they had some guys installing a sprayed-in foam product. Pretty impressive stuff. Seals up every little nook and cranny. I think it is made from a base resin of some sort and an isocyanate which react and make a nifty expanding foam. One guy sprayed the stuff and then they came back and shaved it flush with the studs. They even did the interior walls for sound proofing.

    I have no clue as to how much something like that would cost but they said it was the most energy efficient insulation they could find.
     
  12. Alice In TX/MO

    Alice In TX/MO More dharma, less drama. Supporter

    Messages:
    31,402
    Joined:
    May 10, 2002
    Location:
    Texas and S. Missouri
    Do not use cellulose. We did that years ago. Regret it now. Although it is treated at the time you put it in with chemicals to repel bugs and mice, the mice really think it's a cool habitat now.

    I wish we had gone with fiberglass at the time.

    If I was building new, I would go with the expanding foam.
     
  13. Hoop

    Hoop Well-Known Member

    Messages:
    799
    Joined:
    Jan 1, 2003
    Location:
    Northern Wisconsin
    Cabins with open ceilings (cathedral) MUST be vented on top of the insulation.
    I've seen people build cathedral ceilings with 2 x 6 rafters, and then fill the space between the rafters completely up to the top with fiberglass insulation. NO venting. The roof started to leak in 5 years and the person needed a new roof system in 10 years.
    Lack of venting means the roof system basically rots away.

    Many people in this area build hunting cabins with open ceilings, mainly for aestetic reasons. Unfortunately, once the building is complete, it is difficult and sometimes impossible to insulate.
    Unfortunately, the hunting cabins are then uninsulated, lose heat quickly, and can make for temps of 90 degrees when one goes to sleep and 40 degrees in the morning.

    Best way to insulate a cathedral ceiling is to incorporate a venting system into the design & building of the roof.
     
  14. hunter_53142

    hunter_53142 Member

    Messages:
    5
    Joined:
    Jan 8, 2005
    Location:
    WI
    I'm going to be having the same problem, open rafters in a loft.
    Right now I am letting the roof boards dry (built w/semi-greem lumber).
    I don't want to completely fill the open space as it will make the loft seem smaller.( Bed head board fits up in the opening).

    My plan is to place form board,(1-1/2), then1"x1"srtips along the sides to hold it up, leaving a 1" air gap between the roof boards and the top of the foam. then covering the foam w/carsiding nailed to the strips.
    This should give me about 3" of open rafters exposed.
    Will need to cut in roof vents at the peak and eve vents.

    Right now I do have the problem of 80 degree temps in the loft, even w/ceiling fans to move the air around, but is not to bad as the stove can be dampered down, last most of the nite.
    I also back that up w/electric base boards set at 60 degrees so as to temper the morning air.
    Seems to work well so far.
     
  15. Hoop

    Hoop Well-Known Member

    Messages:
    799
    Joined:
    Jan 1, 2003
    Location:
    Northern Wisconsin
    Hunter,
    What you're describing will work. But you'll only have 1 1/2" of insulation, leaving you with a somewhat meager R value of perhaps R 7.5 or R8.
    Aesthetically, it may be pleasing.....but you may want to consider something less aesthetic and more practical.
    If you put 4 1/2" of insulation between the rafters, it would triple your insulating value. This means lower heat bills in those Wisconsin winters and cooler days in the Wisconsin summers.
    Yes, you'll lose some aesthetic appeal........but gain ground on heating & cooling bills.
     
  16. Blu3duk

    Blu3duk Well-Known Member

    Messages:
    1,859
    Joined:
    Jun 2, 2002
    Location:
    central idaho republic
    The pros and cons of each are debateable by many, those of us who have installed fibreglass will tellyou it sux... it makes a person itch for dayz and can give you eye problems.. the stuff goes everywhere. the fiberglass goes up fairly easy and can be easily cut with a utility knife to length and size if needed, I prefer using the non-backed glass batts for the reason if the studs are mismatched many cuts have to be made and it breathes.... the paperbaked rolls go up faster of course, but has the problem of needing vents on the ceiling/roof or moisture collects and you will rot wood becuase of that.....

    the bubble wrap foil comes in several configurations, and like others posted is best used on the outside if your abode is not already sided... then a person can use the 4 foot rolls and "run" with it, the foil reflects both ways, in a warmer climate it may be all that is needed for insulation, in the northern climates a person may want to add the fibreglass as well to increase the R-value.... here in central Idaho, my neighbor built a single story cabin with cathedral cieling and used only foil paper, even with no one living there it stays above freezing with only the propane hotwater heater running in the fall and spring and a ceramic heater taking over in the zero type temps... Ive checked in on the place a time or two for him....

    stay away from the cans of spray foam.... they impart some severe chemicals and continue to expand for a long time while they dry out.... and if a person waits until they have all the walls up and try it, they will actually find out that those cans will pop the walls [ a local fella who was a math teacher found out the hard way after determining all the free space in his walls and figgering out how many cans the walls would hold] As for the foam mentioned above it may be better, i personally have not been around it yet, but the stuff used 20 years ago was nasty even if it was simple to use.

    As for sheet rock in the loft, the one nice thing about it is it wont catch you with slivers when you touch it... it will add a value of protection from wind finding its way into the cabin loft on the coldest of nghts if sealed up properly... and if you have a mortgage you probably are following a building code of sorts and would need such for a fire safety purposes.... I personally would only put up a T & G cieling and leave it go from that... but i like wood.

    hope that helps out a little too.

    William
     
  17. kabri

    kabri Almst livin the good life

    Messages:
    1,126
    Joined:
    May 14, 2002
    Location:
    W. Washington State
    I don't see a way to do that with 2x4 rafters in a cathedral ceiling, that's what we have, and I'm assuming that's what hunter has too. How would you leave an airspace with 4.5" of insulation as you suggested? Granted, our Rvalue will not be as high, but with only 400 sqft of floor space to heat, wood stove should be sufficient.