Seal in com­fort by seal­ing leaks in home

Winnipeg Free Press - Section G - - HOMES - MIKE HOLMES

BE­FORE you know it, the hot weather will ar­rive and you need to make sure your home is ready for sum­mer. For some peo­ple, that’s sim­ply a mat­ter of tak­ing the cover off the air con­di­tion­ing unit. Some even go one step fur­ther, and have the unit cleaned and ser­viced. (By the way, you don’t need me to tell you that’s a good idea, and you should do it be­fore the hot days ar­rive, or the ser­vice guy will be too busy to get to you.)

I al­ways be­lieve it’s im­por­tant for home­own­ers to ed­u­cate them­selves so they un­der­stand how their house works and why some things might not be work­ing very well. That in­cludes learn­ing about heat­ing and cool­ing your home, and how air­flow works. Un­der­stand­ing that will help you trou­bleshoot prob­lems and make good de­ci­sions about how to main­tain your home, re­duce en­ergy bills and have good indoor air qual­ity.

It’s im­por­tant to un­der­stand that your house is a sys­tem; it all works to­gether in terms of air­flow. And, with newer homes es­pe­cially, that sys­tem is pretty much closed — at least, that’s how it’s de­signed. We don’t want ex­te­rior air leak­ing in, or in­te­rior air leak­ing out. We want the air­flow con­trolled, and air leak­age elim­i­nated or min­i­mized.

Air moves through your house in a pre­dictable way. We all know the ex­pres­sion that hot air rises. What that re­ally means is that cold air, which is more dense than warm air, pushes the warm air up — to the up­per floors of your home, or out through the at­tic space. It’s all driven by ther­mal dif­fer­ence, the dif­fer­ence be­tween the ex­te­rior and in­te­rior tem­per­a­tures of your home, which cre­ates pres­sure and nat­u­ral air con­vec­tion. The big­ger the tem­per­a­ture dif­fer­ence be­tween out­side and in­side, the greater the pres­sure.

Be­cause a vac­uum can’t ex­ist in your home, more cold air is drawn in from lower down, at a lower air pres­sure, which is at ground level or even be­low that, to re­place the warm air. This is called the stack ef­fect.

In your house that re­place­ment air is sucked in through sill plates, cracks in base­ment walls and around win­dows, around your dryer vents, or any vent you might have in your cold room. And typ­i­cally the warm air es­capes through plumb­ing vents and stacks that go through your at­tic, or any break in your in­su­la­tion and vapour bar­rier be­tween your liv­ing space and your at­tic.

Apart from the cost to you in re­plac­ing that con­di­tioned air, how does this af­fect your indoor air qual­ity? Well, since the warm air is be­ing dis­placed, and cold air is be­ing drawn in to re­place it, ask your­self: Where’s that cold air com­ing from? Usu­ally, it’s from your base­ment or crawl space. And given the prob­lems with con­den­sa­tion, mould, spores and mildew that we find in these parts of the house, that’s a bad thing. Aside from the bad smell, it can lead to asthma and al­ler­gies.

An­other area that is low-pres­sure, where re­place­ment air is of­ten drawn from, is an at­tached garage that’s un­con­di­tioned (not heated or cooled). This can be even more un­healthy than air from your base­ment. Garage air might con­tain car­bon monox­ide from ex­haust, as well as what­ever you might have stored in that garage: pes­ti­cides and her­bi­cides, old paint and sol­vents, and gaso­line and oil for your lawn mower.

Even though builders try to cre­ate build­ings with ther­mal bar­ri­ers that cut down on air leak­age, build­ings aren’t sealed. Doors and win­dows open, and there are al­ways leaks. This isn’t about in­su­la­tion, it’s about air and vapour bar­ri­ers. Your at­tic might have lots of in­su­la­tion, but if there’s a prob­lem with the vapour bar­rier, you’ll have leaks.

One thing you should do is seal the leaks in your build­ing en­ve­lope that al­low air to es­cape, and air to be drawn in. Start in your at­tic and check around vents and any ac­cess point be­tween the liv­ing space and the at­tic. Use spray foam and caulk and seal any gaps. Re­mem­ber: You don’t want to seal be­tween the at­tic and out­side; you want to seal be­tween the con­di­tioned liv­ing space and the at­tic. Your at­tic is al­ways sup­posed to re­main the same tem­per­a­ture as out­side, so vents and sof­fits need to stay clear.

If you’ve done what you can to seal off ar­eas of air leak­age, you’ll go a long way to con­trol­ling your cool­ing costs this sum­mer, and im­prov­ing your indoor air qual­ity.

— Canwest News Ser­vice

Find­ing leaks some­times re­quires de­tec­tive work, but the pay­off is worth it.

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