Glossary
This skylight glossary covers the words most homeowners have never had a reason to learn. Curb mount, self flashing, U factor, rough opening. None of it is complicated once someone explains it, and knowing the terms makes it a lot easier to compare what two contractors are actually proposing.
Here are the ones that come up most often.
Acrylic Skylight
Skylights glazed with a plastic lens, most often dome or pyramid shaped. Lenses come in clear, white or bronze and are often doubled up into a double dome.
Curb Mount Skylight
The retainer ring and lenses mount on a 2x wood box frame, which is installed and tied into the existing roof system.
Diffused Light
Indirect light passed through a filter to reduce glare. Solar tubes and sun tunnels use a diffuser to spread light evenly around a room, as do white acrylic domes and frosted glass.
Flashing
Sheet metal or aluminum fabricated into a waterproofing system that covers and protects the transition between the skylight and the roof. Different roofs need different flashing. A tile roof takes a tile pan flashing. A shingle roof takes a step flashing system.
Frame
The skeletal structure of a skylight that mounts to the roof and encases the glass or acrylic. Usually aluminum, because it is light enough to move around on a roof.
Laminated Glass
Two pieces of glass bonded together around a thin layer of vinyl. This makes the glass shatterproof, like a car windshield.
Light Diffusion
The scattering of light caused by passing through a non transparent material or bouncing off semi reflective surfaces. Measured as a haze factor.
LoE3
A metallic glass coating that blocks UV light from passing through the glass. Good for glass skylights because it also improves energy efficiency and reduces fabric fading from sun damage.
Pitch
The angle of a roof. Some roofs, like a flat roof, have no pitch.
Prismatic Sheet
Thermoplastic sheets with embossed pyramid patterns that refract and diffuse light. Common in skylights and other light diffusing applications.
Rafter
The parallel wood studs that support the roof of a home. Rafters sometimes have to be cut, doubled up and mechanically connected with Simpson ties to install a new skylight. This is why it matters that your skylight contractor has hands on structural experience.
Roof Deck
The structural surface fastened across the rafters or trusses, usually plywood or OSB, that the underlayment and roofing material sit on. The rough opening for a skylight is cut through the deck.
Rough Opening
The actual size of the hole cut into the roof deck. Measured between the structural lumber, and it does not include finishing materials like drywall or wood paneling.
Self Flashing Skylight
The skylight and the frame that mounts to the roof surface are one piece.
Tempered Glass
Safety glass that breaks into thousands of small pieces rather than large dangerous shards. The outer layer of glazing on a skylight is typically tempered, because the heat treating process makes it very hard.
Truss
Rigid structural frameworks that carry the load of your roof and structure.
U Factor (U Value)
A measure of the rate of heat transfer, which tells you how well a skylight insulates. Lower is better. 1 divided by the U factor gives you the R value.
Underlayment
A layer of paper or membrane underneath the visible roofing material.
UV Light
Ultraviolet light, an invisible wavelength in the sun’s rays. It causes sunburn on skin and fading on furniture and flooring under a skylight with no UV protection. Glass skylights offer far better UV protection than plastic dome skylights.
Venting Skylight
A skylight hinged on one side that opens at the top to let fresh air in and hot air out. Manually operated or solar powered.
Weep Hole
A small drainage opening in the frame or curb that lets water that gets past the outer seal escape back outside instead of collecting inside the assembly. When weep holes clog with dust or debris, water backs up and shows up as a leak that is not really a leak.
Not In This Skylight Glossary
If you are looking at a quote and cannot tell what you are being sold, call and read it to us. We will tell you what it means.
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