Super Insulating double brick homes

Discussion in 'Designing, building, making and powering your life' started by nchattaway, Jul 1, 2011.

  1. nchattaway

    nchattaway Junior Member

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    Hi All,

    We have a 100 year old farm cottage, which is constructed from local stone for the foundations and "Littlehamptom Brick Co" red bricks in a double wall with central cavity. I'm told the walls are Flemish style, because they have a course across the top to tie the two walls together. This seals the cavity, preventing blow in rockwool type insulation from being installed. Also, the cavity is only around 50mm wide, so access for rockwool is tricky even if you were to remove bricks near the top of the wall to blow it in.

    Double brick provides plenty of thermal mass, but little insulation. In winter in the Adelaide Hills, cold SW winds blow around our home, sucking all warmth from it. The cast iron wood heater can stay on for ages, but the brick walls never warm up.

    I've planted a windbreak to the SW which in a few years will reduce this wind chill factor, but I also want to insulate the outside of the bricks, to provide all that thermal mass with a chance to heat up properly.

    I'm planning to put in standard sized steel houseframe c section, dynabolted directly to my exterior brick walls, which will allow for 600mm wide R3.5 insulation batts to be installed, then cover the lot with lightweight cladding, either zincalume, galv iron or blueboard/render. This will in effect give me a reverse brick veneer, with an air cavity and a second wall of bricks inside the house.

    But all that sounds very materials intensive and the embodied energy will be high. Is there a good permaculture method to achieve excellent insulation for double brick walls?

    I thought of growing ivy on the bricks, but apparently this can be a fire hazard as it can catch embers. Also, I think you only get about R1 equivalent from an ivy covering.

    I'm open to suggestions.

    Also, our floor is lovely old floorboards about 500mm above the ground. Not enough crawlspace to easily insulate under the floor. We don't want to put in underlay and carpet because we love the look and easy care of the timber floors, but we want to be warm too!

    Help!
     
  2. Terra

    Terra Moderator

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    How about polystyrene balls from your old bean bags (or new ones) in the wall cavity they would run to every corner if you could get access .
     
  3. MoD

    MoD Junior Member

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    Well,
    It's hard to have both thermal mass and insulation. TM is for cycling heat/cold thru the walls (i.e. by the time temps have dropped at night the warmth of the day is just making its way into the house and vise versa).
    Sounds like the building tech used was to get some sort of insulation (air) into the structure.

    First thing would be to start asking around your area to see how others have addressed this problem with similar structures. Never know, someone might have a great solution already.


    You could do:
    Foam insulation (there are soy based foams that are non-toxic).
    Cons: might be hard to tell if you've gotten all the pockets filled if you don't know what's behind the walls or if the 50mm is enough space to be effective.
    Also will have cold creeping in as all the bricks are tied together and (I assume) there is no thermal break between the two walls.

    https://www.youtube.com/watch?v=l6KlLqlUy9U

    Insulate the outside.
    Cons: You'll loose any thermal mass cycle (if it was doing any good in the first place)

    What I'd do:

    Build a connected greenhouse on the sun side of the building.
    Insulate the outside of the cold/windy side.
    You'd still get the thermal cycle on the greenhouse side and insulate the other side(s)

    Hope you get it figured out...
     
  4. springtide

    springtide Junior Member

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    There is also that 2 part expander foam that is often pumped into wall cavities for this purpose - as it expands it pushes into most of the air gaps, they drill a series of small holes in the mortar and away it goes. While it is you standard toxic foam product it would be cheaper and retain the look and feel of the house - if you consider your option of timber frame, insulation, blue board + render, etc it maybe more "enviro friendly". I would also go under the house, i spend a lot of time in very small places and although it's not fun you could dig out a 20cm or so trench down the middle to assist and it would make a lot of difference - even using that bubble wrap indulation (R1.5 - 2 i think) with a staple gun (use lots of staples to stop air movement between floor joists). The air gets in through the gaps in floor boards and near the walls there is a gap under the skirting boards where they meet. Actually that may be a good idea - get some "no more gaps" filler and go over everything, behind skirting boards, around window frames where it meets the stone/brick, doors, etc - holes often account for 15%ish of losses even on modern houses, then try the floor, look into MoD's greenhouse idea, then fill the walls with foam. Cheapest to most expensive and see what happens.
     
  5. nchattaway

    nchattaway Junior Member

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    Thanks springtide, MoD and Terra.
    All good suggestions. I was planning on a lean to greenhouse on the northen side anyway, which if I paint the bricks black will act like a Trombe wall that we can also grow food in.

    And I tend to think that insulating the outside of the rest of the bricks is better than bridging the airgap between bricks. I'll rely on the greenhouse, plus the north facing clerestory windows I'm installing, plus a big fat wood burning stove, to heat the thermal mass from the inside.

    Getting under the floor with bubblewrap and a staple gun sounds like a terrible job, but once done, I know it'd make a huge improvement. I'm assuming you staple it to the bottom of the joists and leave it stretched across these, not also stapled to the underside of the floorboards themselves? You could possibly put R3.5 batts up between joists and hold them in with the bubblewrap for a really well insulated floor.
     
  6. Pakanohida

    Pakanohida Junior Member

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    Huh? What? This is a seriously confusing statement after learning about straw bale, cob and Earthship housing. All three building types have thermal mass and good insulation. In fact, an Earthship regularly goes from below freezing (-25f) to well above 100f in a day. The buildings themselves require no heating nor cooling to maintain comfortable temps inside the home, thus your statement is utterly confusing to me.
     
  7. Pakanohida

    Pakanohida Junior Member

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    Huh? What? This is a seriously confusing statement after learning about straw bale, cob and Earthship housing. All three building types have thermal mass and good insulation. In fact, an Earthship regularly goes from below freezing (below 0f not unheard of) to well above 100f in a day. The buildings themselves require no heating nor cooling to maintain comfortable temps inside the home, thus your statement is utterly confusing to me.
     
  8. MoD

    MoD Junior Member

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    Speaking of retrofitting.


    Strawbale houses are low thermal mass (think of the bales as structural insulation) while cob and earthships are high TM.
    TM cycles the heat/cool while insulation blocks heat/cool.
     
  9. MoD

    MoD Junior Member

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    Speaking of retrofitting.


    Strawbale houses are low thermal mass (think of the bales as structural insulation) while cob and earthships are high TM.
    TM cycles the heat/cool while insulation blocks heat/cool.

    nchattaway -
    Have you looked into doing a thermal mass rocket stove as your heat source? Could build a cob bench along the cold wall, run the exhaust pipe thru it and it will slowly radiate the heat into your space.

    https://www.youtube.com/watch?v=hmYaIrHRMLM
     
  10. nchattaway

    nchattaway Junior Member

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    Yes, I was looking at masonry heaters, but a rocket mass heater seems more in my budget.
    So, my priorities are now:
    1. Plant fire resistant hedge along southern and western sides of house for windbreak.Looking at Feijoa (Strawberry Guava)
    2. Insulate and clad the southern, eastern and western walls outside both courses of bricks.
    3. Build a lean-to greenhouse against the northern wall. Paint the exterior brick wall inside the greenhouse black. Insulate the bricks outside the greenhouse as per 1. above.
    4. Get under the floor and staple some bubblewrap to the floor rafters to hold insulation batts up against the floorboards.
    5. Build rocket mass heater for living/kitchen open area.

    Cheers,
    Nathan
     
  11. Mirrabooka

    Mirrabooka Junior Member

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    Heritage

    The 100 year old cottage sounds like a real gem.

    Dynabolting into such brickwork? Certifiable vandalism! The Grandchildren will never forgive you!

    Respect the heritage value of the structure. Do not ruin the aesthetic of the building. You risk losing vital cultural value (and ultimately the financial value of such a charming building when you move on from custody of the building and into the permacultured nursing home in a few decades time).

    Plant around the building (The central idea here is the Permaculture 'suntrapping' of the area as you'll find in Reverend Bill's Bible)- in the short term construct lattice, while waiting for the southern/eastern/western aspects of the evergreen hedging arc to mature- olives, (nitrogen fixing) wattles, bamboo, avocado, citrus - free standing pergola for a deciduous vine to the north and west, with taller deciduous nut or fruit trees (all will be fire retardant- of course, avoid eucalypts and other fire traps) Put a pond north of the house for some summer evaporative air conditioning (and reflected winter sun)

    Install (sympathetic) double glazing and loads of insulation into the roof. Caulk all gaps.
    Replace internal open fireplaces with (potentially removable) fireboxes and flues.

    We do not live by bread alone.

    REgards,
    Mirrabooka
    Flinders
    Victoria
     
  12. nchattaway

    nchattaway Junior Member

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    Hi Mirrabooka,

    I understand your view about heritage value, but previous owners have already:
    Replaced double hung sash windows with cheap awning windows
    Removed bull nosed verandahs from all sides and put up a modern zinc alume verandah on one side
    Built a timber framed weatherboard lean to extension
    Painted all the lovely red bricks with cream paint

    You have to live in a house comfortably before you or anyone else looks at it. After all, that's what houses are for. To me, it seems sensible to greatly increase the performance of the home with external insulation as well as establishing the suntrap/windbreak plantings. I would be cladding the home with corrugated iron, which would weather to an appropriate look for the time and era.

    In any case, after speaking with the engineer, it seems the steel frame that holds the insulation and cladding will be able to be freestanding from the brick walls, removing the need to affix the steel to bricks with dynabolts.

    "Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God." Matthew 4:4
    Why do people only ever quote the first half of that Bible verse? I assume you intended it to mean there's more to life than just eating, including things such as culture and heritage. However, the complete correct quote from the Bible actually weakens your argument. God doesn't want us to worry about appearance and doing honour to man's achievements.

    Do you think for a second that if people 100 years ago had known of the value of internal thermal mass and external insulation they would have hesitated to build in that manner if they had access to the required materials?
    I'm happy with the concept of preserving examples of early Australian architecture intact for heritage and education purposes, but someone else can live in them! I will modify my place into something that performs well at keeping the internal environment compatible with human comfort. We don't worry about future resale value because our family is here to stay. The aspect of the land and the excellent water resources were the primary factors for us choosing this place. We love the high ceilings and polished floorboards of the interior, but the outside has already been well butchered.
     
  13. TheDirtSurgeon

    TheDirtSurgeon Junior Member

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    Of course not. We'd never have heated houses with coal, oil, or natural gas if good insulation and glazing had been invented first. It would have made no sense to buy heat every winter if you could build a house that didn't need it.


    To me, the idea of preserving old houses purely because of their age makes about as much sense as spraying DDT just because they used to do it, back in the day. Sure, old architectural stylings might look appealing, but tear it down and build it right... and you can trim out the new one just like the old one.

    I work in construction, so I guess I could say I'm biased about scraping rubbish houses... but what really infuriates me is building a brand new house that costs $6,000 USD to heat every damn winter. Architects really piss me off. (Oh, but Martha, the view!!! :think: )

    I did build a passive solar house a few years back. It sits at 10,000' elevation in the Rockies, and is heated entirely by trombe walls. Winter lows hit -30F. Building code required a boiler for backup heat. It's never been used in 3 winters. Backup for what, I ask? In case the Sun burns out?

    Anyway... rant over....

    I would say that insulating your floor is the first place to start. Fiberglass batts between the joists, and some kind of air barrier laid on top of the dirt, and try to cut off airflow through the crawlspace during the winter. It's very likely that could make such a significant improvement, that you might not notice anything else.

    Or... if there's bare brick inside... build a brick or stone woodstove directly to the wall so it heats the whole wall?
     
  14. Green_eddie

    Green_eddie Junior Member

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    buy a more efficient heater...
     
  15. Grasshopper

    Grasshopper Senior Member

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    Have you thought of insulated plasterboard?
    Then you dont have to butcher the bricks
     
  16. nchattaway

    nchattaway Junior Member

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    Green_eddie, with all due respect, that's a bit short-sighted. I have a nice efficient wood fuelled stove, but the brickwork absorbs a lot of the heat and then the prevailing south westerley wind whips it away. I'll never get the house to stay toasty warm without a windbreak and good insulation on the outside of all that thermal mass.

    Grasshopper, I assume you refer to lining the inside of the home with insulated plasterboard? This would insulate the living space from the thermal mass, which isn't good. Plus it would butcher the inside bricks.

    I will be installing 100mm x 100mm steel posts every 2m around the house, against the brickwork but not attached to the brickwork. I'll fit R3.5 batts and then clad it with corro, horizontally. I've also bought enough "Photinia Robusta" bushes to establish a windbreak on the southern side of the home. I will try to somehow insulate under the floorboards. This should do the trick.
    Thanks all for the suggestions.
     
  17. Mirrabooka

    Mirrabooka Junior Member

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    It sounds like the solution I need at our place. Can you tell me how your advisor manages the windows and doors with the additional 'wall' depth?

    Thanks
    Mirrabooka
     

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