|
| |
Skylights for Homes
Skylights and roof windows can
provide spaces with the warmth and brightness of natural daylight. They can
enhance almost any interior and are becoming increasingly popular. However, in
order to gain the maximum benefit from a skylight, it's important to understand
the designs, materials, positioning, and proper installation.
- Designs: There is a variety and
shapes and sizes for skylights. The most common are rectangular. The
physical size of the skylight greatly affects the illumination level and
temperature of the space below. As a rule of thumb, the skylight size should
never be more than 5% of the floor area in rooms with many windows and no
more than 15% of the room's total floor area for spaces with few windows. In
very cold weather, skylights are often prone to water vapor condensing on
the glazing. This may cause water to drip into the room. Better skylights
usually have an interior channel to collect the condensation so it can
evaporate later. To eliminate this, efficient skylights (R-4 or greater) are
less prone to condensation problems.
- Fabrication and Materials
Quality: The material used in skylights can impact energy savings, occupant
safety, and unit reliability. Consider the choice of glazing carefully. The
two types commonly used are plastic and glass. Plastic glazing are usually
inexpensive and less liable to break, their surfaces scratch easily and they
may become brittle and discolored over time. Glass is usually found on more
expensive skylights. It is much harder and durable than plastics and do not
discolor. They are often made with a tempered glass on the exterior side and
a laminated pane on the interior side.
- Positioning and Slope: The
location is important, if you want to maximize natural lighting and passive solar
heating potential. Skylights on roofs that face north proved fairly constant
but cool illumination. Skylights on the east provide maximum light and solar
heat gain in the morning. On the west the provide afternoon sunlight and
heat gain. You can prevent unwanted solar heat gain by installing the
skylight in the shade of deciduous (leaf-shedding) trees, or add a movable
shading device. The slope, or tilt, of the skylight also has a great
effect on solar heat gain. A low-slope will admit relatively more solar heat
in the summer and less in the winter, exactly what is desirable. A rule of
thumb is to achieve a slope equal to geographical latitude plus 5 to 15
degrees.
- Preventing Air Leaks: Leaks are
very common with skylights. To avoid them, you should mount the skylight
above the roof surface, install a curb (a raised, watertight lip that helps
to deflect water away from the skylight) and flashing, thoroughly seal
joints, and follow the manufacturer's guidelines. It's also prudent to apply
a layer of sheet waterproofing over the flanges/flashing of the
skylight.
- Buying your skylight: Skylight
prices vary widely. A small skylight starts at $300.00. Expect to pay more
for special glazing materials, venting, shading devices, or other options.
If you choose to have a professional install your skylight, be sure to
obtain several estimates and a list of references. Contractor skills and
fees varies, be wary of any bid that seems too low.
| |
|
