SKYLIGHT DO'S AND DONT'S

AUTHOR'S NOTE: I'll be away this week, so I'm reprising one of Architext's most Googled posts below. 

“Won’t it leak?”  Those are the first three words I hear from clients when I propose using a skylight.   

South-facing skylights may work great in winter,
but beware overheating in summer.

Not to worry.  Today’s skylights are all but leak-proof when they’re properly installed and flashed.  Least troublesome of all are the self-curbing variety, which feature a one-piece welded aluminum curb in place of the old-fashioned wooden curb and its associated waterproofing headaches.  Even interior condensation problems have been eased with the use of built-in gutters which either drain away condensate or hold it until it evaporates naturally.  

However, while skylights may give you fewer technical worries these days, their aesthetics and functionality still demand careful thought.  Here are a few tips:

Integrate your skylights into the design, as seen here;
don't just have them floating at random in the ceiling.

•  Choose the skylight’s location carefully.  First, determine its solar orientation, so you’ll know how much light you’ll be getting.  Too little light won’t justify the installation cost, while too much can make a room intolerably hot.  South-facing skylights in sloping roofs are especially liable to overheat rooms;  north-facing skylights will admit a soft, diffuse light all day long, though they won’t give that sun-splashed effect.  

Most manufacturers offer a range of glazing tints, from clear to gray- or bronze-tinted to translucent white, to suit the skylight’s orientation.  The gray and bronze tints help reduce overheating but still allow direct light, while the translucent white diffuses the light as well. However, you should also plan on some additional form of shading, whether an old-style roller shade or a pleated fabric one on tracks.   

•  Consider the skylight’s appearance both indoors and out.  Inside, try to align the skylight opening with a door, window, or some other existing feature, so that it doesn’t look haphazard.

Mind the skylight's appearance outside.
If possible, avoid having them face the street.
Low-profile skylights or "roof windows"
may look better from the outside.

Outside, avoid installing the skylight on any roof surface that faces the street.  Front-facing skylights look jarringly out of place on traditional home styles, since they were seldom used in the original designs, and often yield a cluttered-looking roof even on Modernist homes.  Discreet concealment is the safest course.

•  Choose a skylight that’s as large as orientation and aesthetics will allow.  A large skylight is cheaper than small one per unit area, and the premium in labor is often marginal.  Frequently, a single large skylight is also preferable to an equivalent group of smaller ones, even if it requires minor reframing.  Multiple units admit less light due to the intervening mullions, require proportionately more labor to install, and have a greater likelihood of leaks due to improper flashing.  

Why complicate things?  Single skylights are widely available in sizes up to five by eight feet, and at least one manufacturer offer standard units up to ten by twelve feet.  

Lots of unusual shapes are available, too.

•  Take advantage of special skylight options.    If you’re not keen on conventional “bubble” skylights, for example, some manufacturers offer special low-profile models.  Some firms will furnish some of their standard skylights with flat glass in place of the usual acrylic plastic bubble.  However, make sure the glass versions will meet your local building and fire codes.

Unusual shapes such as circles, octagons, and pyramids are also available.  Many rectangular skylights can be ordered “operable” (hinged to open a few inches for ventilation).  They can also be fitted with an electric operator controlled by a wall switch--probably a waste of money if the skylight is easy to reach, but a great convenience if it isn’t.