Editor’s note: This is Part 2 of a three-part series. Read Part 1 here and Part 3 here.
Last time, we talked about building code provisions that variously baffle or irritate do-it-yourself builders (and occasionally, seasoned builders as well). While some code requirements may seem arcane at first glance, most have a very simple purpose — to keep you reasonably safe day to day, and possibly to save your life in a real emergency.
There are still a number of different codes in use, along with regional variations (always check with your local jurisdiction), but most of them more or less agree on basic safety provisions.
By way of example, here are some typical code provisions on just one narrow topic — windows — and what they’re meant to accomplish:
In general, codes require every habitable space to have a net window area equal to at least 8 percent of the room’s floor area (a "habitable space" is defined as one intended for living, sleeping, eating or cooking). This is a direct way of ensuring that the major rooms in a house have adequate natural light.
On the other hand, a bathroom could have a much smaller window, because the code doesn’t consider it a habitable space. In fact, as long as a bathroom has a means of mechanical ventilation (that is, an exhaust fan), it doesn’t need a window at all. Still with me? These kinds of building code "gotchas!" are what can drive uninitiated remodelers crazy.
The equivalent of half the required glass area has to be openable for ventilation — again, a simple way to ensure minimum access to fresh air. This provision, too, can cause do-it-yourselfers trouble, since a fixed window (or a window less than half of which opens) may well satisfy the code’s requirements for natural light, but may not make the grade in terms of natural ventilation.
As we noted last time, many code provisions are meant to ensure multiple means of escape — "egress" in code parlance — in case of fire or other emergency. This brings us to yet another set of requirements for windows that are routinely overlooked by do-it-yourselfers. Most codes require that every ground-floor bedroom have at least one "egress window" with an opening of 5 square feet, with a minimum net opening at least 24 inches high and at least 20 inches wide.
Furthermore, the sill of this egress window can’t be more than 44 inches above the floor, so that in an emergency, a small person can still climb out the window by standing on furniture. Bedrooms on upper floors need to have slightly larger egress openings of 5.7 square feet. For obvious reasons, codes also prohibit security bars from being installed over egress windows unless they’re easily openable from inside.
Mind you, these minimum size requirements aren’t just to allow able-bodied occupants to get out of a burning house. They’re also intended to let firefighters wearing bulky breathing apparatus get inside — to rescue, for example, an elderly person or a sleeping child.
Seen in this light — and considering the untold tragedy that building codes have probably averted over the past century — code compliance shouldn’t seem quite such a burden.
Next time: A few genuine building code downsides.
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