Originally Posted by
eesakiwi
Plastic bottles? The 1.25 & 2 litre clear bottles are getting recycled into house insulation here at the moment.
The Goverments just introduced laws requiring all rental houses to be insulated properly so theres been a big demand for roof & underfloor insulation & plastic sheet on the soil under the house for damp.
Our houses are very poorly insulated compared to American houses. We dont have plywood sheet under the roofing or outside walls under the brick or weatherboards.
No underfloor insulation & no basements, often no wall insulation. We use glass fibre insulation here. Not rockwool.
Our temps go from minus -4°C during the winter, up to around +35°C during summer.
The South island is colder with drier air. While the North island is more humid & warmer.
Construction methods here in the states do vary from place to place because it's such a big country. I think you mostly build for the kind of environment that you find yourself in. We have harder winters here in the Northeast. The climate is a little milder here on the coast. Average daytime temps here in the winter are about -6 C. They can drop to -23 C. at night. Add the wind chill factor and that pushes it down to -31 C. The cold is more extreme as you work your way inland.We have snow loads to contend with as well. It's not common but you can get as much as 1 meter of snow on the roof. That's quite a bit of weight. The most common way to build a roof these days is to use a system of engineered trusses for the framework with a 1/2" (13mm) plywood decking. This creates something called a stress skin panel that distributes the weight evenly across the whole structure. It's relatively lightweight and very strong.
Looks like we're taking a lesson from our friends in N.Z. Our traditional roofing material has been asphalt shingles. The metal roofing is really starting to catch on.
Standard insulation in this area is fiberglass batts. We use a minimum of 3.5" (89mm) for floors, 6"(152mm) for walls, and 12" (305mm) in our ceilings.
The ceiling is one of the more important things because it's where you get your most heat loss. It's important in the summertime too. Our daytime temps usually don't get much above 85 F. (29 C.) but the roof surfaces can easily exceed 120 F.(49C.). That radiates a lot of heat downward into the living space. Having lots of insulation in the attic / crawlspace area helps slow the transfer of heat both upward and downward.
We do use blown in cellulose insulation on some jobs. It's basically recycled newsprint that's been shredded up.That works well enough though it does tend to settle and lose it's fluff over time. It's the dead air spaces between the glass fibers -or- between pieces of shredded up newsprint that give you your insulation value so settling is a concern.
Another thing that's been gaining popularity over the last 25 years is blown in foam insulation. The basic idea of it is pretty good but it doesn't seem to be working very well in the real world. You want to avoid any kind of plastics in your building insulation. They can't "breathe". Water vapor gets trapped and quickly rots the building. It's also a heavy contributor to black mold problems.Something to avoid using if at all possible.
As with anything else there always exceptions to the rule. Most of our foundations are either 8' cement, 4' cement, or slab. It's always a good idea to use a heavy plastic under a cement floor as a vapor barrier. 2" foam glued to cement walls is a good insulator and doesn't cause building rot problems.
It all varies ya know ? In the southern part of the U.S. daytime temps can often exceed 100 F ( 38C.) in the summer. Air conditioning is every bit as important to them in the summer as heating is for us in the North during the winter. Good insulation works both ways. It keeps the heat in when it's cold. Keeps the heat out when it's too hot. It pays for itself over time with savings in energy costs. It's a good thing to have if you can possibly afford the up front cost.
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