Roof Windows Center

Skylights, which contribute to an evenly lighted interior, are growing in popularity.

People usually know what they want when it comes to selecting doors and windows, but skylights occupy a more mysterious niche. Inaccessible and above the fray, skylights just sit up there in your roof. What makes one preferable to the next and how it?s installed are questions most of us leave unanswered.

Yet more skylights are appearing in houses all the time. With choices expanding, many homeowners are convinced that one skylight isn’t enough. There’s a growing trend to install several skylights throughout a home, not just in the kitchen or bath, says James Rice, an architect in Myrtle Beach, S.C.

The selection process is easier than many homeowners think because almost any skylight can work if it’s properly installed. So let’s head up to the roof.

FIRST PRIORITY: NO LEAKS

If you’re not going the DIY route, hire a skylight specialist. Someone who?s an excellent roofer or general carpenter might not have much experience installing skylights, says Chris Stathopulo of C & L Remodeling, a Dallas, Texas, company with 20 years in the skylight business. Ninety-nine percent of skylight problems are caused by the installation, not the skylight itself, he says.

Skylights are installed in one of two ways, either directly on the deck with mounting brackets or on a boxlike frame called a curb. Curb-mounted skylights are best for roofs that have a shallow pitch, says Alan Foss, owner of Foss Remodeling and Design in Buffalo Grove, Ill. ?Another place I use curb-mounted skylights, he says, is near sidewalls that increase runoff toward the skylight.? Building up the curb height helps to keep the skylight above water that is running down the roof.

Curb-mounted units have step flashing around the frame to shed water. The flashing is made up of top and bottom caps, and L-shaped side pieces that are woven into the shingle courses. Deck-mounted skylights are installed with step flashing, too. Flashing kits are available for various roof types such as tile, metal and shakes. You?ll also find easy-to-install self-flashing models that are suitable for asphalt-shingle roofs.

THE DIY SOLUTION

If you do the job yourself, choose a product with clear installation instructions, which you can check at a manufacturer’s Web site or by calling its customer support number. An incorrect installation may cause leaks and void the skylight?s warranty.

Here’s another installer’s trick that keeps a skylight high and dry: Install a waterproof underlayment before the flashing and shingles go on.

The adhesive-back underlayment runs from the plywood roof sheathing up the sides of the curb and effectively seals the hole cut in the roof, explains Todd Brown, vice president of Pacific Northwest Skylights, a Kirkland, Wash., firm that installs 500 skylights a year. Brown says watertight installation is ensured by wrapping the entire skylight assembly with the material.

Source: www.popularmechanics.com

Daylighting is the practice of placing windows, or other transparent media, and reflective surfaces so that, during the day, natural light provides effective internal illumination.

Within the overall architectural design of a building, particular attention is given to daylighting when the aim is to maximize visual comfort, productivity, or to reduce energy use. Energy savings from daylighting are achieved in two ways - either from the reduced use of electric lighting, or from passive solar heating or cooling.

Skylights are often used for daylighting. Skylights admit more light per unit area than windows, and distribute it more evenly over a space. They can therefore be a good choice when daylight is being used to illuminate a space. The optimum number of skylights (usually quantified as ?effective aperture?) varies according to climate, latitude, and the characteristics of the skylight, but is usually 1-10% of floor area. The thermal performance of skylights is affected by stratification, i.e. the tendency of warm air to collect in the skylight wells, which in cool climates increases the rate of heat loss. During warm seasons, skylights also can cause internal heat problems, which is usually treated by placing a shade over the skylight, or by opening it if it is openable.

The amount of light skylights deliver peaks around midday, when the additional light and heat it provides is least needed. Some skylight designs use domed or pyramidal shapes along with prismatic or other light-redirecting glazings to achieve more even light levels through the course of a day. Poorly constructed or installed skylights may have leak problems and single-paned ones may weep with condensation. Using skylights with at least two panes and a heat reflecting coating will increase their energy efficiency. Skylights may also be more prone to breakage than vertical windows.

The skylight topic is controversial. Although roof-angled glass provides good daylighting, it can also create a solar furnace in the summer (when the sun is nearly perpendicular), and then lose more solar gain than it captures (when the low winter sun reflects off of it,and warm interior air rises to touch the cold glass on winter nights). Heating and cooling costs for a building are normally greater than the value of skylight daylighting, especially when modern energy-efficient lighting systems are employed.

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Source: Wikipedia.org