One of the main concerns with installing a skylight is location. Often the place where you want the skylight will have a ceiling that's not close to the roof. In other words, there's an attic in between. There are two basic solutions here. The first is to create a light shaft on the site, with the usual building materials. The shaft, sometimes quite large, connects the ceiling to the roof. It is typically open on the bot¬tom, and the skylight is placed on top. Artificial lighting can be added for the evening. With very large shafts, an attractive ledge can be added around the perimeter on which to place plants or knick-knacks. On the other hand, tubular skylights, noted above, solve this problem easily.
Another concern is that the skylight be properly installed. Many do-it-yourselfers today prefer the flush-mount self-flashing models. You simply remove the appropriate amount of roofing, cut the hole to the correct size, and mount the skylight right on top. The flashing, used to keep out water, comes with the unit and you replace the roofing material right on top. The less expensive edge- or curb-mounted models require that a curb be built onto the roof to accommodate the skylight and that flashing be manufactured on the site. Professional installation is required.
If the skylight is not properly installed, it will indeed leak. For that reason professional installation is recommended. However, a do-it-yourselfer who purchases a flush-mount self-flashing unit and fol¬lows the instructions carefully should not have problems. Beware of installing skylights on tile roofs. The roofs themselves are fragile and simply walking on them incorrectly can result in breaking the tiles.
Some homes do not have attics. Rather, there is roofing on one side of the rafters, insulation in between, and ceiling on the other side. In such cases an attractive look can be achieved, without disturbing the structural integrity of the roof, by leaving the rafters in place. Simply have the skylight installed on the roof, remove the ceiling and insulation, and block the space between the rafters. Having the rafters exposed below the skylight offers a very modern look. (Just be sure to use a sealed skylight. An open one would expose the rafters to excessive weathering.)
Also, when framing a larger skylight, be careful not to weaken the roof by cutting rafters. This is particularly important if your roof has snowload requirements. Whenever possible, insert the skylight between two existing rafters. If the space is too narrow, you'll have to cut one beam and strengthen the remaining rafters before framing the skylight box. In a big job, always check with an engineer on how best to best construct the box and strengthen the remaining rafters.
A final installation concern is the weather. It should go without saying that when you have the skylight installed, pick a day when no rain is forecast. You don't want to have a hole cut in the roof just as it starts pouring. It's always amazing to me that installers seem oblivious to the weather. They're often so confident that they can get the job done quickly (and they don't get paid unless they're working) that they start a skylight project when the weather is threatening. Put your foot down and don't let work begin unless the sun is shining.
