Howard Winter wrote: > It's interesting how many different items are being mentioned by Americans that are unheard-of over here - Attic fans, for example! Do attics have > very open venting from the rest of the house, so that that evacuating them causes air to flow up from the house? Insulation has been a big thing > here for quite some time, and the Building Regulations insist on quite high levels of insulation these days. I've never seen a house with shingles for a > roof - slates or tiles are the norm. Central Heating is usually by hot water, either with radiators (often with a thermostatic valve on each one) or > increasingly these days underfloor. > > [snip] > And if I achieved my ultimate goal - being the sole winner of a triple-rollover on the lottery - I'd have a hangar and a runway! > > Cheers, > > > Howard Winter > St.Albans, England > > > Hi Howard, others.... here's a run-down on the building mechanisms required in some of the colder clime's in North America... I live in Toronto, and I believe I understand why things are the way they are. Working from the bottom up... water. Water is supplied to the house in pipes. If the pipe is too close to the surface, it will freeze in winter. Freezing water may burst the pipes, which is a Bad Thing(c). In Toronto, it is about 4' underground that the pipes come in to the house. Thus, pretty much *every* house has a basement, which allows the water to enter the "warmer" house and not freeze in winter. Because the basement is a requirement of the water supply, it has become a large part of the practicality of the house, and is used for all sorts of things. Specifically, all the utilities (Electricity, Cable, telephone, Gas, and potentially other things) all come in to the basement typically in one place, where there is a board mounted on the basement wall for the distribution of the utilities, and a breaker/fuse box. Expanding on the theme of the basement, there is also all the heavy mechanical things in there, such as the furnace, hot water tank, etc. The furnace involves a few other things that take space such as all the distribution and return duct-work, and gas lines. Many houses also have a water softener, and other things (humidifier, heat-exchange, etc). The space in the basement that is not used for the utilities is either used as storage, workshops and playrooms. Many houses have "finnished" basements which are most often "granny flats", bedrooms, or alternate living rooms. New houses seldom have finnished basements because there may be moisture leaks through the basement walls, and also heaving may crack the walls while the ground outside the house settles (heaving is earth movement caused by the freezing/thawing cycles in the ground). Thus, it is normally recommended that basements should only be finnished after at least one full year. Regardless, the basement is a big feature of most houses. So much so, that an attic is not needed for storage, etc. The attic is a critical component of the winter durability of the house as well, although most Canadians do not understand why. It comes down to moisture. In the canadian winter, the air is really dry. No humidity. This is because whatever humidity there is freezes, and falls out of the air. The air inside the house is warm, and much more humid than the air outside. If the air inside the house comes in contact with a cold surface, it will condense, and potentially freeze. This moisture *must* *never* condense inside the walls, etc, or there will be mildew/fungus problems in the house. A plastic vapour barrier is used to wrap the house up, and *outside* the barrier you will find the insulation. This keeps the moist air inside the house walls, and always insulated. The same thing happens in the ceiling of the house. Just abouve the ceiling is a plastic vapour barrier, and above that is about a foot of insulation. This keeps the warm moist air inside the house, and more importantly, it keeps the moist air warm (no condensation). You may ask "Why don't they do that in the roof, rather than above the ceiling?". The answer is Snow! Insulation is not perfect, some heat escapes from the house, and warms up the air above the ceiling, but below the roof (the attic space). If this air gets warm, then the snow resting on the roof will start melting. Specifically, it will melt, then freeeze, melt, and freeze, etc as the days cool, weather changes, etc. This causes the roof to get damaged. It is *much* better for the roof if the snow never melted, so, you ventilate the attic so that the freexing air from outside the house circulates through the attic, and displaces the air that has been warmed by escaping heat from the house. Houses with poorly insulated ceilings and poorly ventilated attics have icicles hanging from the roof. Well insulated houses/ventilated attics do not. It may seem counter-intuitive, but in winter it is desirable for the air in the attic space to be as cool as the air outside the house. The purpose of the roof in winter is to keep the snow from melting! In summer, the attic space can become incredibly hot (heated by the sun). It is very important to circulate this hot air outside in order to keep the temperature under control inside the house. Again, the attic needs to be ventilated. In both summer and winter it is important to have very good insulation between the house and the attic, and to have a very well ventilated attic space. An attic fan is a great idea if there would otherwise be poor ventilation. The roof is designed with soffits (where the roof meets the walls of the house) that are perforated allowing air to flow thorough from under the eaves of the roof to the attic. many newer houses also have "ridge Vents" which allow the heat to escape though the top of the roof in summer/winter. Many roofs have other ventilation mechanisms (spinning chimneys, etc). Here is a reference to the sorts of issues we face: http://www.joneakes.com/cgi-bin/getdetailscals.cgi?id=621 http://en.wikipedia.org/wiki/Ice_dam Rolf -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist