Uninstalled square or rectangular skylights, whether dome or flat-top, can cost up to $ 2,000 each if they have shading and ventilation capabilities. Some of the newer models also have special internal channels to trap condensation, not to mention they have motor-driven vents and louvers (these are very expensive). Therefore, for certain homeowners who want at least a flat skylight, it is more practical to have them fabricate a new or replacement one.
Since this article is for do-it-yourself (DYI) people, it only provides the basic materials and processes for making and installing a two-square-foot flatbed model, leaving any modifications to size, tools used, and other details to your own experience.
Materials and cost (assuming a ceiling-to-ceiling skylight has already been installed).
- a 96-inch 2×4-inch pressure-treated board (to make a 3.5-inch-tall curb frame, $ 4); note: the so-called 2×4 inch dash is actually 1.5×3.5 inch
- two square pieces of 0.22-inch thick clear or frosted plexiglass: (1) the top one, 24.5-inch square; and (2) the bottom one, 20.75 inches (about $ 25 each, depending on availability)
- twelve or more # 8×1-inch wide head drywall screws (to secure top plexiglass to curb frame)
- a 96-inch long piece of quarter-inch square molding or similar ($ 3)
- slim metal aluminum counter or flashing strips if desired ($ 10-20); note: a high-quality putty can be used instead
- a standard tube the size of a long lasting acrylic caulk gun similar in color to the ceiling ($ 4)
- Enough nails or screws to attach the trim to the curb and to secure the curb to the roof sheeting or subfloor
- a quarter of paint of the selected color
Construction and placement.
1. Cut the 2×4-inch board into four pieces: two 24-inch long and two 21-inch long.
2. Assemble these pieces into a 24-inch vertical square curb frame (outside to outside) with eight 2.5 to 3-inch screws, two at each corner.
3. Cut and position the quarter-inch trim flush with the inside bottom of the curb all the way around your 21-inch inside square. This trim will hold the 20.75-inch square piece of Plexiglass on the underside that will act as a condensation shield on the underside of the curb frame.
4. Paint frame inside and out, matching desired colors similar to ramp walls and / or shingles. Let it dry.
5. Clean a 24-inch square area above the open duct by cutting the shingles and tar paper to this size.
6. Lay the center of the dry frame over the ramp, allowing the shingles to fit fairly tightly around the outside of the curb.
7. Nail or screw the frame to the ceiling wood slats.
8. Clean and place the 20.75-inch plexiglass on the bottom of the curb frame where it will be placed over the trim.
9. If desired, flash or flash the outside of the frame (these strips are woven under or inside the shingles starting at the bottom end of the sloped curb frame). Let the strips cover the outside of the curb to its top surface where it cuts flush with that surface. If not, caulk the shingles on the outside of the curb to prevent rain from dripping around it.
10. Clean and position the 24.5-inch plexiglass centered on the top of the curb. A small border will hang over the outside edge of the curb.
11. Drill 12 slightly oversized screw holes, evenly spaced, around, but not into, the edge of the Plexiglass on the curb.
12. Screw 12 broad head drywall screws through these holes in the curb, snug, but not too tight.
13. Seal the top plexiglass to the curb and / or its flashing (below the edge) with long-lasting sealant.
14. If necessary, paint the flashing.
Thin metal flashing on vents, chimneys, and other items that protrude from roofs is the professional way to seal the roof around you. This procedure also eliminates the need to paint the exterior of the skylight curb. However, today’s durable caulking putties are reliable sealant materials. They can be used in place or in combination with the flashing used. This caulking also saves construction time and material costs.
Also, if the thick plexiglass on top cracks for any reason, such as large hail or flying debris, it can easily be replaced with another piece from a nearby hardware store. This replacement cost is about one-tenth that of a new skylight. For more information on skylight fabrication and DYI flashing, check out these sites.