Skylights and Solar Tubes

Skylight construction

Skylight construction consists of three main components: the viewing glass, often called the glazing, the roof curb on which the glass sits and the shaft that directs sunlight into the home. The viewing glass can be constructed of either acrylic or polycarbonate plastic; however, window glass can also be used.

Some homeowners prefer plastic skylights because they are lightweight and economical. However, however plastic glazings do have some design limitations because they are molded. Flat rectangles, domes, bubbles and pyramids are some of the shapes that can be used. Because they are less expensive than glass skylight, they are often good choices, but cracking or potential breakage is possible.

Many homeowners prefer to use glass skylights because they are scratch-resistant and have more design options. With either glass or plastic glazings, the skylight can be constructed with single, double, or triple glazing. Skylight can also be constructed of low-E glass or argon gas-filled panes that will assist in energy efficiency. Thermal resisting skylights will have an R-value rating that is an indicator of the materials resistance to heat flow. The higher the R-value, the better insulating properties the glass has.

The skylight will also have a U-value, which is another indicator of heat flow resistance. However, this rating not only takes into account the glazing material, but also the frame and all related parts. Coatings can also be added to the glazing to block the UV rays of the sun. The rating will be expressed as a percentage of blocked rays. UV blocking will protect carpeting and furniture from sun damage.

While frames are often constructed of solid wood or aluminum, combinations of wood, metal and plastic are becoming more popular. Integrated flashing may be attached to the frame to assist in water resistance; however, additional flashing is often used to ensure protection from leaks.

Another part of the frame, the part you see inside the home, is called the shaft and is often made of plywood, solid wood or vinyl. The shaft can be configured in several ways. Straight shafts will direct the light straight down. The four sides of the shaft can be flared outward, spreading the light over a wider area. For a directional lighting effect, one or two of the shaft sides can be flared and the other sides kept perpendicular.

Additonal features

Blinds can also be installed on skylighting and can be operated either manually or electrically. Another popular option that is often used is the ventilating skylight. These skylights can actually open up to allow heat to escape from the room, saving on air conditioning costs.

Manual hand cranks or electrical motors can be used to operate the ventilating skylight. Hand switches, remote controls or an automatic temperature sensor can be used to activate the skylight. These skylights are usually equipped with screening to prevent bugs and other pests from entering the home.

Tubular skylights

Another type of skylight, the flexible tubular light, is another option available. These round skylight are smaller, usually with sizes from 10 to 21 inches in diameter. They can illuminate an area that is from 100 to 600 square feet.

The smaller size fits between rafters and ceiling joists, negating the need for extensive carpentry work and framing. There are usually no structural changes to be made. The tubular skylight is easier and less expensive to install, with the installation accomplished in under three hours in most cases.

Light is reflected into the room by a tubular shaft that is constructed with a highly reflective coating on the inside. The reflective coating allows the tube to be flexible, enabling it to route around stationary obstructions in the attic, such as vent pipes or framing support members.

While the homeowner will not see the sky directly through this type of skylight, it is excellent for bringing the natural light into the room, especially in smaller rooms. This makes it an excellent choice for bathrooms.

These skylights can also be manufactured with UV inhibitors, keeping the sun’s rays from damaging or fading the cloth in carpeting and furniture. This domed skylight can be mounted on virtually any type of roof, including metal, ceramic tile, concrete and the more conventional wood or asphalt shingles. Additionally, these smaller skylights can save money on air conditioning bills because they keep any heat gain to a minimum.

Installing a skylight

While any skylight can be mounted on almost any type of roof, it is better if they are installed on sloping roofs to prevent water collection and damage. This is especially true of rectangular skylights because they cover more area and could be more prone to leaks.

It is possible to install a skylight yourself, but since installation requires making cuts through the roof and the ceiling, it's a job best left to an experienced professional. Roofing contractors or window installers who offer skylight products are your most likely professional choices when selecting a contractor.

Skylights can run in sizes of up to 8 feet in length. Standard skylights come in sizes from 14 inches to 4 feet square. Larger sizes can be custom ordered; however, architects and designers will often specify groups of smaller skylights in various configurations instead of single, large skylights.

When it comes to sizing the skylights, there are no hard and fast rules, codes or standards. However, there are some recommendations that are based on the use of the external lighting in the room. For example, if the room is used for normal activities, then the recommended size is around 5 percent of the floor space.

For frequently used work areas, a 10-percent ratio is suggested. Heavy-duty usage areas, such as home offices, kitchens and family rooms, can be adequately lighted by using a skylight or series of skylights that are equal to 15 percent of the total floor area.

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